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| id ▼ | page | ref | title | content | breadcrumbs | references |
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| internals:database-close | internals | database-close | db.close() | Closes all of the open connections to file-backed databases. This is mainly intended to be used by large test suites, to avoid hitting limits on the number of open files. | ["Internals for plugins", "Database class"] | [] |
| internals:database-constructor | internals | database-constructor | Database(ds, path=None, is_mutable=True, is_memory=False, memory_name=None) | The Database() constructor can be used by plugins, in conjunction with .add_database(db, name=None, route=None) , to create and register new databases. The arguments are as follows: ds - Datasette class (required) The Datasette instance you are attaching this database to. path - string Path to a SQLite database file on disk. is_mutable - boolean Set this to False to cause Datasette to open the file in immutable mode. is_memory - boolean Use this to create non-shared memory connections. memory_name - string or None Use this to create a named in-memory database. Unlike regular memory databases these can be accessed by multiple threads and will persist an changes made to them for the lifetime of the Datasette server process. The first argument is the datasette instance you are attaching to, the second is a path= , then is_mutable and is_memory are both optional arguments. | ["Internals for plugins", "Database class"] | [] |
| internals:database-execute | internals | database-execute | await db.execute(sql, ...) | Executes a SQL query against the database and returns the resulting rows (see Results ). sql - string (required) The SQL query to execute. This can include ? or :named parameters. params - list or dict A list or dictionary of values to use for the parameters. List for ? , dictionary for :named . truncate - boolean Should the rows returned by the query be truncated at the maximum page size? Defaults to True , set this to False to disable truncation. custom_time_limit - integer ms A custom time limit for this query. This can be set to a lower value than the Datasette configured default. If a query takes longer than this it will be terminated early and raise a dataette.database.QueryInterrupted exception. page_size - integer Set a custom page size for truncation, over-riding the configured Datasette default. log_sql_errors - boolean Should any SQL errors be logged to the console in addition to being raised as an error? Defaults to True . | ["Internals for plugins", "Database class"] | [] |
| internals:database-execute-fn | internals | database-execute-fn | await db.execute_fn(fn) | Executes a given callback function against a read-only database connection running in a thread. The function will be passed a SQLite connection, and the return value from the function will be returned by the await . Example usage: def get_version(conn): return conn.execute( "select sqlite_version()" ).fetchall()[0][0] version = await db.execute_fn(get_version) | ["Internals for plugins", "Database class"] | [] |
| internals:database-execute-isolated-fn | internals | database-execute-isolated-fn | await db.execute_isolated_fn(fn) | This method works is similar to execute_write_fn() but executes the provided function in an entirely isolated SQLite connection, which is opened, used and then closed again in a single call to this method. The prepare_connection() plugin hook is not executed against this connection. This allows plugins to execute database operations that might conflict with how database connections are usually configured. For example, running a VACUUM operation while bypassing any restrictions placed by the datasette-sqlite-authorizer plugin. Plugins can also use this method to load potentially dangerous SQLite extensions, use them to perform an operation and then have them safely unloaded at the end of the call, without risk of exposing them to other connections. Functions run using execute_isolated_fn() share the same queue as execute_write_fn() , which guarantees that no writes can be executed at the same time as the isolated function is executing. The return value of the function will be returned by this method. Any exceptions raised by the function will be raised out of the await line as well. | ["Internals for plugins", "Database class"] | [{"href": "https://github.com/datasette/datasette-sqlite-authorizer", "label": "datasette-sqlite-authorizer"}] |
| internals:database-execute-write | internals | database-execute-write | await db.execute_write(sql, params=None, block=True) | SQLite only allows one database connection to write at a time. Datasette handles this for you by maintaining a queue of writes to be executed against a given database. Plugins can submit write operations to this queue and they will be executed in the order in which they are received. This method can be used to queue up a non-SELECT SQL query to be executed against a single write connection to the database. You can pass additional SQL parameters as a tuple or dictionary. The method will block until the operation is completed, and the return value will be the return from calling conn.execute(...) using the underlying sqlite3 Python library. If you pass block=False this behavior changes to "fire and forget" - queries will be added to the write queue and executed in a separate thread while your code can continue to do other things. The method will return a UUID representing the queued task. Each call to execute_write() will be executed inside a transaction. | ["Internals for plugins", "Database class"] | [] |
| internals:database-execute-write-fn | internals | database-execute-write-fn | await db.execute_write_fn(fn, block=True, transaction=True) | This method works like .execute_write() , but instead of a SQL statement you give it a callable Python function. Your function will be queued up and then called when the write connection is available, passing that connection as the argument to the function. The function can then perform multiple actions, safe in the knowledge that it has exclusive access to the single writable connection for as long as it is executing. fn needs to be a regular function, not an async def function. For example: def delete_and_return_count(conn): conn.execute("delete from some_table where id > 5") return conn.execute( "select count(*) from some_table" ).fetchone()[0] try: num_rows_left = await database.execute_write_fn( delete_and_return_count ) except Exception as e: print("An error occurred:", e) The value returned from await database.execute_write_fn(...) will be the return value from your function. If your function raises an exception that exception will be propagated up to the await line. By default your function will be executed inside a transaction. You can pass transaction=False to disable this behavior, though if you do that you should be careful to manually apply transactions - ideally using the with conn: pattern, or you may see OperationalError: database table is locked errors. If you specify block=False the method becomes fire-and-forget, queueing your function to be executed and then allowing your code after the call to .execute_write_fn() to continue running while the underlying thread waits for an opportunity to run your function. A UUID representing the queued task will be returned. Any exceptions in your code will be silently swallowed. | ["Internals for plugins", "Database class"] | [] |
| internals:database-execute-write-many | internals | database-execute-write-many | await db.execute_write_many(sql, params_seq, block=True) | Like execute_write() but uses the sqlite3 conn.executemany() method. This will efficiently execute the same SQL statement against each of the parameters in the params_seq iterator, for example: await db.execute_write_many( "insert into characters (id, name) values (?, ?)", [(1, "Melanie"), (2, "Selma"), (2, "Viktor")], ) Each call to execute_write_many() will be executed inside a transaction. | ["Internals for plugins", "Database class"] | [{"href": "https://docs.python.org/3/library/sqlite3.html#sqlite3.Cursor.executemany", "label": "conn.executemany()"}] |
| internals:database-execute-write-script | internals | database-execute-write-script | await db.execute_write_script(sql, block=True) | Like execute_write() but can be used to send multiple SQL statements in a single string separated by semicolons, using the sqlite3 conn.executescript() method. Each call to execute_write_script() will be executed inside a transaction. | ["Internals for plugins", "Database class"] | [{"href": "https://docs.python.org/3/library/sqlite3.html#sqlite3.Cursor.executescript", "label": "conn.executescript()"}] |
| internals:database-hash | internals | database-hash | db.hash | If the database was opened in immutable mode, this property returns the 64 character SHA-256 hash of the database contents as a string. Otherwise it returns None . | ["Internals for plugins", "Database class"] | [] |
| internals:database-results | internals | database-results | Results | The db.execute() method returns a single Results object. This can be used to access the rows returned by the query. Iterating over a Results object will yield SQLite Row objects . Each of these can be treated as a tuple or can be accessed using row["column"] syntax: info = [] results = await db.execute("select name from sqlite_master") for row in results: info.append(row["name"]) The Results object also has the following properties and methods: .truncated - boolean Indicates if this query was truncated - if it returned more results than the specified page_size . If this is true then the results object will only provide access to the first page_size rows in the query result. You can disable truncation by passing truncate=False to the db.query() method. .columns - list of strings A list of column names returned by the query. .rows - list of sqlite3.Row This property provides direct access to the list of rows returned by the database. You can access specific rows by index using results.rows[0] . .dicts() - list of dict This method returns a list of Python dictionaries, one for each row. .first() - row or None Returns the first row in the results, or None if no rows were returned. … | ["Internals for plugins", "Database class"] | [{"href": "https://docs.python.org/3/library/sqlite3.html#row-objects", "label": "Row objects"}] |
| internals:datasette-absolute-url | internals | datasette-absolute-url | .absolute_url(request, path) | request - Request The current Request object path - string A path, for example /dbname/table.json Returns the absolute URL for the given path, including the protocol and host. For example: absolute_url = datasette.absolute_url( request, "/dbname/table.json" ) # Would return "http://localhost:8001/dbname/table.json" The current request object is used to determine the hostname and protocol that should be used for the returned URL. The force_https_urls configuration setting is taken into account. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-actors-from-ids | internals | datasette-actors-from-ids | await .actors_from_ids(actor_ids) | actor_ids - list of strings or integers A list of actor IDs to look up. Returns a dictionary, where the keys are the IDs passed to it and the values are the corresponding actor dictionaries. This method is mainly designed to be used with plugins. See the actors_from_ids(datasette, actor_ids) documentation for details. If no plugins that implement that hook are installed, the default return value looks like this: { "1": {"id": "1"}, "2": {"id": "2"} } | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-add-database | internals | datasette-add-database | .add_database(db, name=None, route=None) | db - datasette.database.Database instance The database to be attached. name - string, optional The name to be used for this database . If not specified Datasette will pick one based on the filename or memory name. route - string, optional This will be used in the URL path. If not specified, it will default to the same thing as the name . The datasette.add_database(db) method lets you add a new database to the current Datasette instance. The db parameter should be an instance of the datasette.database.Database class. For example: from datasette.database import Database datasette.add_database( Database( datasette, path="path/to/my-new-database.db", ) ) This will add a mutable database and serve it at /my-new-database . Use is_mutable=False to add an immutable database. .add_database() returns the Database instance, with its name set as the database.name attribute. Any time you are working with a newly added database you should use the return value of .add_database() , for example: db = datasette.add_database( Database(datasette, memory_name="statistics") ) await db.execute_write( "CREATE TABLE foo(id integer primary key)" ) | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-add-memory-database | internals | datasette-add-memory-database | .add_memory_database(name) | Adds a shared in-memory database with the specified name: datasette.add_memory_database("statistics") This is a shortcut for the following: from datasette.database import Database datasette.add_database( Database(datasette, memory_name="statistics") ) Using either of these pattern will result in the in-memory database being served at /statistics . | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-add-message | internals | datasette-add-message | .add_message(request, message, type=datasette.INFO) | request - Request The current Request object message - string The message string type - constant, optional The message type - datasette.INFO , datasette.WARNING or datasette.ERROR Datasette's flash messaging mechanism allows you to add a message that will be displayed to the user on the next page that they visit. Messages are persisted in a ds_messages cookie. This method adds a message to that cookie. You can try out these messages (including the different visual styling of the three message types) using the /-/messages debugging tool. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-check-visibility | internals | datasette-check-visibility | await .check_visibility(actor, action=None, resource=None, permissions=None) | actor - dictionary The authenticated actor. This is usually request.actor . action - string, optional The name of the action that is being permission checked. resource - string or tuple, optional The resource, e.g. the name of the database, or a tuple of two strings containing the name of the database and the name of the table. Only some permissions apply to a resource. permissions - list of action strings or (action, resource) tuples, optional Provide this instead of action and resource to check multiple permissions at once. This convenience method can be used to answer the question "should this item be considered private, in that it is visible to me but it is not visible to anonymous users?" It returns a tuple of two booleans, (visible, private) . visible indicates if the actor can see this resource. private will be True if an anonymous user would not be able to view the resource. This example checks if the user can access a specific table, and sets private so that a padlock icon can later be displayed: visible, private = await datasette.check_visibility( request.actor, action="view-table", resource=(database, table), ) The following example runs three checks in a row, similar to await .ensure_permissions(actor, permissions) . If any of the checks are denied before one of them is explicitly granted then visible will be … | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-create-token | internals | datasette-create-token | .create_token(actor_id, expires_after=None, restrict_all=None, restrict_database=None, restrict_resource=None) | actor_id - string The ID of the actor to create a token for. expires_after - int, optional The number of seconds after which the token should expire. restrict_all - iterable, optional A list of actions that this token should be restricted to across all databases and resources. restrict_database - dict, optional For restricting actions within specific databases, e.g. {"mydb": ["view-table", "view-query"]} . restrict_resource - dict, optional For restricting actions to specific resources (tables, SQL views and Canned queries ) within a database. For example: {"mydb": {"mytable": ["insert-row", "update-row"]}} . This method returns a signed API token of the format dstok_... which can be used to authenticate requests to the Datasette API. All tokens must have an actor_id string indicating the ID of the actor which the token will act on behalf of. Tokens default to lasting forever, but can be set to expire after a given number of seconds using the expires_after argument. The following code creates a token for user1 that will expire after an hour: token = datasette.create_token( actor_id="user1", expires_after=3600, ) The three restrict_* arguments can be used to create a token that has … | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-databases | internals | datasette-databases | .databases | Property exposing a collections.OrderedDict of databases currently connected to Datasette. The dictionary keys are the name of the database that is used in the URL - e.g. /fixtures would have a key of "fixtures" . The values are Database class instances. All databases are listed, irrespective of user permissions. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-ensure-permissions | internals | datasette-ensure-permissions | await .ensure_permissions(actor, permissions) | actor - dictionary The authenticated actor. This is usually request.actor . permissions - list A list of permissions to check. Each permission in that list can be a string action name or a 2-tuple of (action, resource) . This method allows multiple permissions to be checked at once. It raises a datasette.Forbidden exception if any of the checks are denied before one of them is explicitly granted. This is useful when you need to check multiple permissions at once. For example, an actor should be able to view a table if either one of the following checks returns True or not a single one of them returns False : await datasette.ensure_permissions( request.actor, [ ("view-table", (database, table)), ("view-database", database), "view-instance", ], ) | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-get-column-metadata | internals | datasette-get-column-metadata | await .get_column_metadata(self, database_name, resource_name, column_name) | database_name - string The name of the database to query. resource_name - string The name of the resource (table, view, or canned query) inside database_name to query. column_name - string The name of the column inside resource_name to query. Returns metadata keys and values for the specified column, resource, and table as a dictionary. Internally queries the metadata_columns table inside the internal database . | ["Internals for plugins", "Datasette class", "Getting and setting metadata"] | [] |
| internals:datasette-get-database | internals | datasette-get-database | .get_database(name) | name - string, optional The name of the database - optional. Returns the specified database object. Raises a KeyError if the database does not exist. Call this method without an argument to return the first connected database. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-get-database-metadata | internals | datasette-get-database-metadata | await .get_database_metadata(self, database_name) | database_name - string The name of the database to query. Returns metadata keys and values for the specified database as a dictionary. Internally queries the metadata_databases table inside the internal database . | ["Internals for plugins", "Datasette class", "Getting and setting metadata"] | [] |
| internals:datasette-get-instance-metadata | internals | datasette-get-instance-metadata | await .get_instance_metadata(self) | Returns metadata keys and values for the entire Datasette instance as a dictionary. Internally queries the metadata_instance table inside the internal database . | ["Internals for plugins", "Datasette class", "Getting and setting metadata"] | [] |
| internals:datasette-get-permission | internals | datasette-get-permission | .get_permission(name_or_abbr) | name_or_abbr - string The name or abbreviation of the permission to look up, e.g. view-table or vt . Returns a Permission object representing the permission, or raises a KeyError if one is not found. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-get-resource-metadata | internals | datasette-get-resource-metadata | await .get_resource_metadata(self, database_name, resource_name) | database_name - string The name of the database to query. resource_name - string The name of the resource (table, view, or canned query) inside database_name to query. Returns metadata keys and values for the specified "resource" as a dictionary. A "resource" in this context can be a table, view, or canned query. Internally queries the metadata_resources table inside the internal database . | ["Internals for plugins", "Datasette class", "Getting and setting metadata"] | [] |
| internals:datasette-get-set-metadata | internals | datasette-get-set-metadata | Getting and setting metadata | Metadata about the instance, databases, tables and columns is stored in tables in Datasette's internal database . The following methods are the supported API for plugins to read and update that stored metadata. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-permission-allowed | internals | datasette-permission-allowed | await .permission_allowed(actor, action, resource=None, default=...) | actor - dictionary The authenticated actor. This is usually request.actor . action - string The name of the action that is being permission checked. resource - string or tuple, optional The resource, e.g. the name of the database, or a tuple of two strings containing the name of the database and the name of the table. Only some permissions apply to a resource. default - optional: True, False or None What value should be returned by default if nothing provides an opinion on this permission check. Set to True for default allow or False for default deny. If not specified the default from the Permission() tuple that was registered using register_permissions(datasette) will be used. Check if the given actor has permission to perform the given action on the given resource. Some permission checks are carried out against rules defined in datasette.yaml , while other custom permissions may be decided by plugins that implement the permission_allowed(datasette, actor, action, resource) plugin hook. If neither metadata.json nor any of the plugins provide an answer to the permission query the default argument will be returned. See Built-in permissions for a full list of permission actions included in Datasette core. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-permissions | internals | datasette-permissions | .permissions | Property exposing a dictionary of permissions that have been registered using the register_permissions(datasette) plugin hook. The dictionary keys are the permission names - e.g. view-instance - and the values are Permission() objects describing the permission. Here is a description of that object . | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-plugin-config | internals | datasette-plugin-config | .plugin_config(plugin_name, database=None, table=None) | plugin_name - string The name of the plugin to look up configuration for. Usually this is something similar to datasette-cluster-map . database - None or string The database the user is interacting with. table - None or string The table the user is interacting with. This method lets you read plugin configuration values that were set in datasette.yaml . See Writing plugins that accept configuration for full details of how this method should be used. The return value will be the value from the configuration file - usually a dictionary. If the plugin is not configured the return value will be None . | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-remove-database | internals | datasette-remove-database | .remove_database(name) | name - string The name of the database to be removed. This removes a database that has been previously added. name= is the unique name of that database. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-render-template | internals | datasette-render-template | await .render_template(template, context=None, request=None) | template - string, list of strings or jinja2.Template The template file to be rendered, e.g. my_plugin.html . Datasette will search for this file first in the --template-dir= location, if it was specified - then in the plugin's bundled templates and finally in Datasette's set of default templates. If this is a list of template file names then the first one that exists will be loaded and rendered. If this is a Jinja Template object it will be used directly. context - None or a Python dictionary The context variables to pass to the template. request - request object or None If you pass a Datasette request object here it will be made available to the template. Renders a Jinja template using Datasette's preconfigured instance of Jinja and returns the resulting string. The template will have access to Datasette's default template functions and any functions that have been made available by other plugins. | ["Internals for plugins", "Datasette class"] | [{"href": "https://jinja.palletsprojects.com/en/2.11.x/api/#jinja2.Template", "label": "Template object"}, {"href": "https://jinja.palletsprojects.com/en/2.11.x/", "label": "Jinja template"}] |
| internals:datasette-resolve-database | internals | datasette-resolve-database | .resolve_database(request) | request - Request object A request object If you are implementing your own custom views, you may need to resolve the database that the user is requesting based on a URL path. If the regular expression for your route declares a database named group, you can use this method to resolve the database object. This returns a Database instance. If the database cannot be found, it raises a datasette.utils.asgi.DatabaseNotFound exception - which is a subclass of datasette.utils.asgi.NotFound with a .database_name attribute set to the name of the database that was requested. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-resolve-row | internals | datasette-resolve-row | .resolve_row(request) | request - Request object A request object This method assumes your route declares named groups for database , table and pks . It returns a ResolvedRow named tuple instance with the following fields: db - Database The database object table - string The name of the table sql - string SQL snippet that can be used in a WHERE clause to select the row params - dict Parameters that should be passed to the SQL query pks - list List of primary key column names pk_values - list List of primary key values decoded from the URL row - sqlite3.Row The row itself If the database or table cannot be found it raises a datasette.utils.asgi.DatabaseNotFound exception. If the table does not exist it raises a datasette.utils.asgi.TableNotFound … | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-resolve-table | internals | datasette-resolve-table | .resolve_table(request) | request - Request object A request object This assumes that the regular expression for your route declares both a database and a table named group. It returns a ResolvedTable named tuple instance with the following fields: db - Database The database object table - string The name of the table (or view) is_view - boolean True if this is a view, False if it is a table If the database or table cannot be found it raises a datasette.utils.asgi.DatabaseNotFound exception. If the table does not exist it raises a datasette.utils.asgi.TableNotFound exception - a subclass of datasette.utils.asgi.NotFound with .database_name and .table attributes. | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-set-column-metadata | internals | datasette-set-column-metadata | await .set_column_metadata(self, database_name, resource_name, column_name, key, value) | database_name - string The database the metadata entry belongs to. resource_name - string The resource (table, view, or canned query) the metadata entry belongs to. column-name - string The column the metadata entry belongs to. key - string The metadata entry key to insert (ex title , description , etc.) value - string The value of the metadata entry to insert. Adds a new metadata entry for the specified column. Any previous column-level metadata entry with the same key will be overwritten. Internally upserts the value into the the metadata_columns table inside the internal database . | ["Internals for plugins", "Datasette class", "Getting and setting metadata"] | [] |
| internals:datasette-set-database-metadata | internals | datasette-set-database-metadata | await .set_database_metadata(self, database_name, key, value) | database_name - string The database the metadata entry belongs to. key - string The metadata entry key to insert (ex title , description , etc.) value - string The value of the metadata entry to insert. Adds a new metadata entry for the specified database. Any previous database-level metadata entry with the same key will be overwritten. Internally upserts the value into the the metadata_databases table inside the internal database . | ["Internals for plugins", "Datasette class", "Getting and setting metadata"] | [] |
| internals:datasette-set-instance-metadata | internals | datasette-set-instance-metadata | await .set_instance_metadata(self, key, value) | key - string The metadata entry key to insert (ex title , description , etc.) value - string The value of the metadata entry to insert. Adds a new metadata entry for the entire Datasette instance. Any previous instance-level metadata entry with the same key will be overwritten. Internally upserts the value into the the metadata_instance table inside the internal database . | ["Internals for plugins", "Datasette class", "Getting and setting metadata"] | [] |
| internals:datasette-set-resource-metadata | internals | datasette-set-resource-metadata | await .set_resource_metadata(self, database_name, resource_name, key, value) | database_name - string The database the metadata entry belongs to. resource_name - string The resource (table, view, or canned query) the metadata entry belongs to. key - string The metadata entry key to insert (ex title , description , etc.) value - string The value of the metadata entry to insert. Adds a new metadata entry for the specified "resource". Any previous resource-level metadata entry with the same key will be overwritten. Internally upserts the value into the the metadata_resources table inside the internal database . | ["Internals for plugins", "Datasette class", "Getting and setting metadata"] | [] |
| internals:datasette-setting | internals | datasette-setting | .setting(key) | key - string The name of the setting, e.g. base_url . Returns the configured value for the specified setting . This can be a string, boolean or integer depending on the requested setting. For example: downloads_are_allowed = datasette.setting("allow_download") | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-sign | internals | datasette-sign | .sign(value, namespace="default") | value - any serializable type The value to be signed. namespace - string, optional An alternative namespace, see the itsdangerous salt documentation . Utility method for signing values, such that you can safely pass data to and from an untrusted environment. This is a wrapper around the itsdangerous library. This method returns a signed string, which can be decoded and verified using .unsign(value, namespace="default") . | ["Internals for plugins", "Datasette class"] | [{"href": "https://itsdangerous.palletsprojects.com/en/1.1.x/serializer/#the-salt", "label": "itsdangerous salt documentation"}, {"href": "https://itsdangerous.palletsprojects.com/", "label": "itsdangerous"}] |
| internals:datasette-track-event | internals | datasette-track-event | await .track_event(event) | event - Event An instance of a subclass of datasette.events.Event . Plugins can call this to track events, using classes they have previously registered. See Event tracking for details. The event will then be passed to all plugins that have registered to receive events using the track_event(datasette, event) hook. Example usage, assuming the plugin has previously registered the BanUserEvent class: await datasette.track_event( BanUserEvent(user={"id": 1, "username": "cleverbot"}) ) | ["Internals for plugins", "Datasette class"] | [] |
| internals:datasette-unsign | internals | datasette-unsign | .unsign(value, namespace="default") | signed - any serializable type The signed string that was created using .sign(value, namespace="default") . namespace - string, optional The alternative namespace, if one was used. Returns the original, decoded object that was passed to .sign(value, namespace="default") . If the signature is not valid this raises a itsdangerous.BadSignature exception. | ["Internals for plugins", "Datasette class"] | [] |
| internals:id1 | internals | id1 | .get_internal_database() | Returns a database object for reading and writing to the private internal database . | ["Internals for plugins", "Datasette class"] | [] |
| internals:internals | internals | internals | Internals for plugins | Many Plugin hooks are passed objects that provide access to internal Datasette functionality. The interface to these objects should not be considered stable with the exception of methods that are documented here. | [] | [] |
| internals:internals-csrf | internals | internals-csrf | CSRF protection | Datasette uses asgi-csrf to guard against CSRF attacks on form POST submissions. Users receive a ds_csrftoken cookie which is compared against the csrftoken form field (or x-csrftoken HTTP header) for every incoming request. If your plugin implements a <form method="POST"> anywhere you will need to include that token. You can do so with the following template snippet: <input type="hidden" name="csrftoken" value="{{ csrftoken() }}"> If you are rendering templates using the await .render_template(template, context=None, request=None) method the csrftoken() helper will only work if you provide the request= argument to that method. If you forget to do this you will see the following error: form-urlencoded POST field did not match cookie You can selectively disable CSRF protection using the skip_csrf(datasette, scope) hook. | ["Internals for plugins"] | [{"href": "https://github.com/simonw/asgi-csrf", "label": "asgi-csrf"}] |
| internals:internals-database | internals | internals-database | Database class | Instances of the Database class can be used to execute queries against attached SQLite databases, and to run introspection against their schemas. | ["Internals for plugins"] | [] |
| internals:internals-database-introspection | internals | internals-database-introspection | Database introspection | The Database class also provides properties and methods for introspecting the database. db.name - string The name of the database - usually the filename without the .db prefix. db.size - integer The size of the database file in bytes. 0 for :memory: databases. db.mtime_ns - integer or None The last modification time of the database file in nanoseconds since the epoch. None for :memory: databases. db.is_mutable - boolean Is this database mutable, and allowed to accept writes? db.is_memory - boolean Is this database an in-memory database? await db.attached_databases() - list of named tuples Returns a list of additional databases that have been connected to this database using the SQLite ATTACH command. Each named tuple has fields seq , name and file . await db.table_exists(table) - boolean Check if a table called table exists. await db.view_exists(view) - boolean … | ["Internals for plugins", "Database class"] | [] |
| internals:internals-datasette | internals | internals-datasette | Datasette class | This object is an instance of the Datasette class, passed to many plugin hooks as an argument called datasette . You can create your own instance of this - for example to help write tests for a plugin - like so: from datasette.app import Datasette # With no arguments a single in-memory database will be attached datasette = Datasette() # The files= argument can load files from disk datasette = Datasette(files=["/path/to/my-database.db"]) # Pass metadata as a JSON dictionary like this datasette = Datasette( files=["/path/to/my-database.db"], metadata={ "databases": { "my-database": { "description": "This is my database" } } }, ) Constructor parameters include: files=[...] - a list of database files to open immutables=[...] - a list of database files to open in immutable mode metadata={...} - a dictionary of Metadata config_dir=... - the configuration directory to use, stored in datasette.config_dir | ["Internals for plugins"] | [] |
| internals:internals-datasette-client | internals | internals-datasette-client | datasette.client | Plugins can make internal simulated HTTP requests to the Datasette instance within which they are running. This ensures that all of Datasette's external JSON APIs are also available to plugins, while avoiding the overhead of making an external HTTP call to access those APIs. The datasette.client object is a wrapper around the HTTPX Python library , providing an async-friendly API that is similar to the widely used Requests library . It offers the following methods: await datasette.client.get(path, **kwargs) - returns HTTPX Response Execute an internal GET request against that path. await datasette.client.post(path, **kwargs) - returns HTTPX Response Execute an internal POST request. Use data={"name": "value"} to pass form parameters. await datasette.client.options(path, **kwargs) - returns HTTPX Response Execute an internal OPTIONS request. await datasette.client.head(path, **kwargs) - returns HTTPX Response Execute an internal HEAD request. await datasette.client.put(path, **kwargs) - returns HTTPX Response Execute an internal PUT request. await datasette.client.patch(path, **kwargs) - returns HTTPX Response … | ["Internals for plugins", "Datasette class"] | [{"href": "https://www.python-httpx.org/", "label": "HTTPX Python library"}, {"href": "https://requests.readthedocs.io/", "label": "Requests library"}, {"href": "https://www.python-httpx.org/async/", "label": "HTTPX Async documentation"}] |
| internals:internals-datasette-urls | internals | internals-datasette-urls | datasette.urls | The datasette.urls object contains methods for building URLs to pages within Datasette. Plugins should use this to link to pages, since these methods take into account any base_url configuration setting that might be in effect. datasette.urls.instance(format=None) Returns the URL to the Datasette instance root page. This is usually "/" . datasette.urls.path(path, format=None) Takes a path and returns the full path, taking base_url into account. For example, datasette.urls.path("-/logout") will return the path to the logout page, which will be "/-/logout" by default or /prefix-path/-/logout if base_url is set to /prefix-path/ datasette.urls.logout() Returns the URL to the logout page, usually "/-/logout" datasette.urls.static(path) Returns the URL of one of Datasette's default static assets, for example "/-/static/app.css" datasette.urls.static_plugins(plugin_name, path) Returns the URL of one of the static assets belonging to a plugin. datasette.urls.static_plugins("datasette_cluster_map", "datasette-cluster-map.js") would return "/-/static-plugins/datasette_cluster_map/datasette-cluster-map.js" datasette.urls.static(path) … | ["Internals for plugins", "Datasette class"] | [] |
| internals:internals-internal | internals | internals-internal | Datasette's internal database | Datasette maintains an "internal" SQLite database used for configuration, caching, and storage. Plugins can store configuration, settings, and other data inside this database. By default, Datasette will use a temporary in-memory SQLite database as the internal database, which is created at startup and destroyed at shutdown. Users of Datasette can optionally pass in a --internal flag to specify the path to a SQLite database to use as the internal database, which will persist internal data across Datasette instances. Datasette maintains tables called catalog_databases , catalog_tables , catalog_columns , catalog_indexes , catalog_foreign_keys with details of the attached databases and their schemas. These tables should not be considered a stable API - they may change between Datasette releases. Metadata is stored in tables metadata_instance , metadata_databases , metadata_resources and metadata_columns . Plugins can interact with these tables via the get_*_metadata() and set_*_metadata() methods . The internal database is not exposed in the Datasette application by default, which means private data can safely be stored without worry of accidentally leaking information through the default Datasette interface and API. However, other plugins do have full read and write access to the internal database. Plugins can access this database by calling internal_db = datasette.get_internal_database() and then executing queries using the Database API . Plugin authors are asked to practice good etiquette when using the internal database, as all plugins use the same database to store data. For example: Use a unique prefix when creating tables, indices, and triggers in the internal database. If your plugin is called datasette-xyz , then prefix names with datasette_xyz_* . Avoid long-running write statements that may stall or block ot… | ["Internals for plugins"] | [] |
| internals:internals-internal-schema | internals | internals-internal-schema | Internal database schema | The internal database schema is as follows: [[[cog from metadata_doc import internal_schema internal_schema(cog) ]]] CREATE TABLE catalog_databases ( database_name TEXT PRIMARY KEY, path TEXT, is_memory INTEGER, schema_version INTEGER ); CREATE TABLE catalog_tables ( database_name TEXT, table_name TEXT, rootpage INTEGER, sql TEXT, PRIMARY KEY (database_name, table_name), FOREIGN KEY (database_name) REFERENCES catalog_databases(database_name) ); CREATE TABLE catalog_columns ( database_name TEXT, table_name TEXT, cid INTEGER, name TEXT, type TEXT, "notnull" INTEGER, default_value TEXT, -- renamed from dflt_value is_pk INTEGER, -- renamed from pk hidden INTEGER, PRIMARY KEY (database_name, table_name, name), FOREIGN KEY (database_name) REFERENCES catalog_databases(database_name), FOREIGN KEY (database_name, table_name) REFERENCES catalog_tables(database_name, table_name) ); CREATE TABLE catalog_indexes ( database_name TEXT, table_name TEXT, seq INTEGER, name TEXT, "unique" INTEGER, origin TEXT, partial INTEGER, PRIMARY KEY (database_name, table_name, name), FOREIGN KEY (database_name) REFERENCES catalog_databases(database_name), FOREIGN KEY (database_name, table_name) REFERENCES catalog_tables(database_name, table_name) ); CREATE TABLE catalog_foreign_keys ( database_name TEXT, table_name TEXT, id INTEGER, seq INTEGER, "table" TEXT, "from" TEXT, "to" TEXT, on_update TEXT, on_delete TEXT, match TEXT, PRIMARY KEY (database_name, table_name, id, seq), FOREIGN KEY (database_name) REFERENCES catalog_databases(database_name), FOREIGN KEY (database_name, table_name) REFERENCES catalog_tables(database_name, table_name) ); CREATE TABLE metadata_instance ( key text, value text, unique(key) ); CREATE TABLE metadata_databases ( database_name text, key text, value text, u… | ["Internals for plugins", "Datasette's internal database"] | [] |
| internals:internals-multiparams | internals | internals-multiparams | The MultiParams class | request.args is a MultiParams object - a dictionary-like object which provides access to query string parameters that may have multiple values. Consider the query string ?foo=1&foo=2&bar=3 - with two values for foo and one value for bar . request.args[key] - string Returns the first value for that key, or raises a KeyError if the key is missing. For the above example request.args["foo"] would return "1" . request.args.get(key) - string or None Returns the first value for that key, or None if the key is missing. Pass a second argument to specify a different default, e.g. q = request.args.get("q", "") . request.args.getlist(key) - list of strings Returns the list of strings for that key. request.args.getlist("foo") would return ["1", "2"] in the above example. request.args.getlist("bar") would return ["3"] . If the key is missing an empty list will be returned. request.args.keys() - list of strings Returns the list of available keys - for the example this would be ["foo", "bar"] . key in request.args - True or False You can use if key in request.args to check if a key is present. for key in request.args - iterator This lets you loop through every available key. le… | ["Internals for plugins"] | [] |
| internals:internals-request | internals | internals-request | Request object | The request object is passed to various plugin hooks. It represents an incoming HTTP request. It has the following properties: .scope - dictionary The ASGI scope that was used to construct this request, described in the ASGI HTTP connection scope specification. .method - string The HTTP method for this request, usually GET or POST . .url - string The full URL for this request, e.g. https://latest.datasette.io/fixtures . .scheme - string The request scheme - usually https or http . .headers - dictionary (str -> str) A dictionary of incoming HTTP request headers. Header names have been converted to lowercase. .cookies - dictionary (str -> str) A dictionary of incoming cookies .host - string The host header from the incoming request, e.g. latest.datasette.io or localhost . .path - string The path of the request excluding the query string, e.g. /fixtures . .full_path - string The path of the… | ["Internals for plugins"] | [{"href": "https://asgi.readthedocs.io/en/latest/specs/www.html#connection-scope", "label": "ASGI HTTP connection scope"}] |
| internals:internals-response | internals | internals-response | Response class | The Response class can be returned from view functions that have been registered using the register_routes(datasette) hook. The Response() constructor takes the following arguments: body - string The body of the response. status - integer (optional) The HTTP status - defaults to 200. headers - dictionary (optional) A dictionary of extra HTTP headers, e.g. {"x-hello": "world"} . content_type - string (optional) The content-type for the response. Defaults to text/plain . For example: from datasette.utils.asgi import Response response = Response( "<xml>This is XML</xml>", content_type="application/xml; charset=utf-8", ) The quickest way to create responses is using the Response.text(...) , Response.html(...) , Response.json(...) or Response.redirect(...) helper methods: from datasette.utils.asgi import Response html_response = Response.html("This is HTML") json_response = Response.json({"this_is": "json"}) text_response = Response.text( "This will become utf-8 encoded text" ) # Redirects are served as 302, unless you pass status=301: redirect_response = Response.redirect( "https://latest.datasette.io/" ) Each of these responses will use the correct corresponding content-type - text/html; charset=utf-8 , application/json; charset=utf-8 or text/plain; charset=utf-8 respectively. Each of the helper methods take optional status= and headers= argument… | ["Internals for plugins"] | [] |
| internals:internals-response-asgi-send | internals | internals-response-asgi-send | Returning a response with .asgi_send(send) | In most cases you will return Response objects from your own view functions. You can also use a Response instance to respond at a lower level via ASGI, for example if you are writing code that uses the asgi_wrapper(datasette) hook. Create a Response object and then use await response.asgi_send(send) , passing the ASGI send function. For example: async def require_authorization(scope, receive, send): response = Response.text( "401 Authorization Required", headers={ "www-authenticate": 'Basic realm="Datasette", charset="UTF-8"' }, status=401, ) await response.asgi_send(send) | ["Internals for plugins", "Response class"] | [] |
| internals:internals-response-set-cookie | internals | internals-response-set-cookie | Setting cookies with response.set_cookie() | To set cookies on the response, use the response.set_cookie(...) method. The method signature looks like this: def set_cookie( self, key, value="", max_age=None, expires=None, path="/", domain=None, secure=False, httponly=False, samesite="lax", ): ... You can use this with datasette.sign() to set signed cookies. Here's how you would set the ds_actor cookie for use with Datasette authentication : response = Response.redirect("/") response.set_cookie( "ds_actor", datasette.sign({"a": {"id": "cleopaws"}}, "actor"), ) return response | ["Internals for plugins", "Response class"] | [] |
| internals:internals-shortcuts | internals | internals-shortcuts | Import shortcuts | The following commonly used symbols can be imported directly from the datasette module: from datasette import Response from datasette import Forbidden from datasette import NotFound from datasette import hookimpl from datasette import actor_matches_allow | ["Internals for plugins"] | [] |
| internals:internals-tilde-encoding | internals | internals-tilde-encoding | Tilde encoding | Datasette uses a custom encoding scheme in some places, called tilde encoding . This is primarily used for table names and row primary keys, to avoid any confusion between / characters in those values and the Datasette URLs that reference them. Tilde encoding uses the same algorithm as URL percent-encoding , but with the ~ tilde character used in place of % . Any character other than ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz0123456789_- will be replaced by the numeric equivalent preceded by a tilde. For example: / becomes ~2F . becomes ~2E % becomes ~25 ~ becomes ~7E Space becomes + polls/2022.primary becomes polls~2F2022~2Eprimary Note that the space character is a special case: it will be replaced with a + symbol. datasette.utils. tilde_encode s : str str Returns tilde-encoded string - for example /foo/bar -> ~2Ffoo~2Fbar datasette.utils. tilde_decode s : str str Decodes a tilde-encoded string, so ~2Ffoo~2Fbar -> /foo/bar | ["Internals for plugins", "The datasette.utils module"] | [{"href": "https://developer.mozilla.org/en-US/docs/Glossary/percent-encoding", "label": "URL percent-encoding"}] |
| internals:internals-tracer | internals | internals-tracer | datasette.tracer | Running Datasette with --setting trace_debug 1 enables trace debug output, which can then be viewed by adding ?_trace=1 to the query string for any page. You can see an example of this at the bottom of latest.datasette.io/fixtures/facetable?_trace=1 . The JSON output shows full details of every SQL query that was executed to generate the page. The datasette-pretty-traces plugin can be installed to provide a more readable display of this information. You can see a demo of that here . You can add your own custom traces to the JSON output using the trace() context manager. This takes a string that identifies the type of trace being recorded, and records any keyword arguments as additional JSON keys on the resulting trace object. The start and end time, duration and a traceback of where the trace was executed will be automatically attached to the JSON object. This example uses trace to record the start, end and duration of any HTTP GET requests made using the function: from datasette.tracer import trace import httpx async def fetch_url(url): with trace("fetch-url", url=url): async with httpx.AsyncClient() as client: return await client.get(url) | ["Internals for plugins"] | [{"href": "https://latest.datasette.io/fixtures/facetable?_trace=1", "label": "latest.datasette.io/fixtures/facetable?_trace=1"}, {"href": "https://datasette.io/plugins/datasette-pretty-traces", "label": "datasette-pretty-traces"}, {"href": "https://latest-with-plugins.datasette.io/github/commits?_trace=1", "label": "a demo of that here"}] |
| internals:internals-tracer-trace-child-tasks | internals | internals-tracer-trace-child-tasks | Tracing child tasks | If your code uses a mechanism such as asyncio.gather() to execute code in additional tasks you may find that some of the traces are missing from the display. You can use the trace_child_tasks() context manager to ensure these child tasks are correctly handled. from datasette import tracer with tracer.trace_child_tasks(): results = await asyncio.gather( # ... async tasks here ) This example uses the register_routes() plugin hook to add a page at /parallel-queries which executes two SQL queries in parallel using asyncio.gather() and returns their results. from datasette import hookimpl from datasette import tracer @hookimpl def register_routes(): async def parallel_queries(datasette): db = datasette.get_database() with tracer.trace_child_tasks(): one, two = await asyncio.gather( db.execute("select 1"), db.execute("select 2"), ) return Response.json( { "one": one.single_value(), "two": two.single_value(), } ) return [ (r"/parallel-queries$", parallel_queries), ] Note that running parallel SQL queries in this way has been known to cause problems in the past , so treat this example with caution. Adding ?_trace=1 will show that the trace covers both of those child tasks. | ["Internals for plugins", "datasette.tracer"] | [{"href": "https://github.com/simonw/datasette/issues/2189", "label": "been known to cause problems in the past"}] |
| internals:internals-utils | internals | internals-utils | The datasette.utils module | The datasette.utils module contains various utility functions used by Datasette. As a general rule you should consider anything in this module to be unstable - functions and classes here could change without warning or be removed entirely between Datasette releases, without being mentioned in the release notes. The exception to this rule is anything that is documented here. If you find a need for an undocumented utility function in your own work, consider opening an issue requesting that the function you are using be upgraded to documented and supported status. | ["Internals for plugins"] | [{"href": "https://github.com/simonw/datasette/issues/new", "label": "opening an issue"}] |
| internals:internals-utils-await-me-maybe | internals | internals-utils-await-me-maybe | await_me_maybe(value) | Utility function for calling await on a return value if it is awaitable, otherwise returning the value. This is used by Datasette to support plugin hooks that can optionally return awaitable functions. Read more about this function in The “await me maybe” pattern for Python asyncio . async datasette.utils. await_me_maybe value : Any Any If value is callable, call it. If awaitable, await it. Otherwise return it. | ["Internals for plugins", "The datasette.utils module"] | [{"href": "https://simonwillison.net/2020/Sep/2/await-me-maybe/", "label": "The “await me maybe” pattern for Python asyncio"}] |
| internals:internals-utils-named-parameters | internals | internals-utils-named-parameters | named_parameters(sql) | Derive the list of :named parameters referenced in a SQL query. datasette.utils. named_parameters sql : str List [ str ] Given a SQL statement, return a list of named parameters that are used in the statement e.g. for select * from foo where id=:id this would return ["id"] | ["Internals for plugins", "The datasette.utils module"] | [] |
| internals:internals-utils-parse-metadata | internals | internals-utils-parse-metadata | parse_metadata(content) | This function accepts a string containing either JSON or YAML, expected to be of the format described in Metadata . It returns a nested Python dictionary representing the parsed data from that string. If the metadata cannot be parsed as either JSON or YAML the function will raise a utils.BadMetadataError exception. datasette.utils. parse_metadata content : str dict Detects if content is JSON or YAML and parses it appropriately. | ["Internals for plugins", "The datasette.utils module"] | [] |
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