{"id": "plugin_hooks:plugin-actions", "page": "plugin_hooks", "ref": "plugin-actions", "title": "Action hooks", "content": "Action hooks can be used to add items to the action menus that appear at the top of different pages within Datasette. Unlike menu_links() , actions which are displayed on every page, actions should only be relevant to the page the user is currently viewing. \n Each of these hooks should return return a list of {\"href\": \"...\", \"label\": \"...\"} menu items, with optional \"description\": \"...\" keys describing each action in more detail. \n They can alternatively return an async def awaitable function which, when called, returns a list of those menu items.", "breadcrumbs": "[\"Plugin hooks\"]", "references": "[]"} {"id": "plugin_hooks:id1", "page": "plugin_hooks", "ref": "id1", "title": "Plugin hooks", "content": "Datasette plugins use plugin hooks to customize Datasette's behavior. These hooks are powered by the pluggy plugin system. \n Each plugin can implement one or more hooks using the @hookimpl decorator against a function named that matches one of the hooks documented on this page. \n When you implement a plugin hook you can accept any or all of the parameters that are documented as being passed to that hook. \n For example, you can implement the render_cell plugin hook like this even though the full documented hook signature is render_cell(row, value, column, table, database, datasette) : \n @hookimpl\ndef render_cell(value, column):\n if column == \"stars\":\n return \"*\" * int(value) \n \n List of plugin hooks \n \n \n prepare_connection(conn, database, datasette) \n \n \n prepare_jinja2_environment(env, datasette) \n \n \n Page extras \n \n \n extra_template_vars(template, database, table, columns, view_name, request, datasette) \n \n \n extra_css_urls(template, database, table, columns, view_name, request, datasette) \n \n \n extra_js_urls(template, database, table, columns, view_name, request, datasette) \n \n \n extra_body_script(template, database, table, columns, view_name, request, datasette) \n \n \n \n \n publish_subcommand(publish) \n \n \n render_cell(row, value, column, table, database, datasette, request) \n \n \n register_output_renderer(datasette) \n \n \n register_routes(datasette) \n \n \n register_commands(cli) \n \n \n register_facet_classes() \n \n \n register_permissions(datasette) \n \n \n asgi_wrapper(datasette) \n \n \n startup(datasette) \n \n \n canned_queries(datasette, database, actor) \n \n \n actor_from_request(datasette, request) \n \n \n actors_from_ids(datasette, actor_ids) \n \n \n jinja2_environment_from_request(datasette, request, env) \n \n \n filters_from_request(request, database, table, datasette) \n \n \n permission_allowed(datasette, actor, action, resource) \n \n \n register_magic_parameters(datasette) \n \n \n forbidden(datasette, request, message) \n \n \n handle_exception(datasette, request, exception) \n \n \n skip_csrf(datasette, scope) \n \n \n get_metadata(datasette, key, database, table) \n \n \n menu_links(datasette, actor, request) \n \n \n Action hooks \n \n \n table_actions(datasette, actor, database, table, request) \n \n \n view_actions(datasette, actor, database, view, request) \n \n \n query_actions(datasette, actor, database, query_name, request, sql, params) \n \n \n row_actions(datasette, actor, request, database, table, row) \n \n \n database_actions(datasette, actor, database, request) \n \n \n homepage_actions(datasette, actor, request) \n \n \n \n \n Template slots \n \n \n top_homepage(datasette, request) \n \n \n top_database(datasette, request, database) \n \n \n top_table(datasette, request, database, table) \n \n \n top_row(datasette, request, database, table, row) \n \n \n top_query(datasette, request, database, sql) \n \n \n top_canned_query(datasette, request, database, query_name) \n \n \n \n \n Event tracking \n \n \n track_event(datasette, event) \n \n \n register_events(datasette)", "breadcrumbs": "[]", "references": "[{\"href\": \"https://pluggy.readthedocs.io/\", \"label\": \"pluggy\"}]"} {"id": "plugin_hooks:plugin-event-tracking", "page": "plugin_hooks", "ref": "plugin-event-tracking", "title": "Event tracking", "content": "Datasette includes an internal mechanism for tracking notable events. This can be used for analytics, but can also be used by plugins that want to listen out for when key events occur (such as a table being created) and take action in response. \n Plugins can register to receive events using the track_event plugin hook. \n They can also define their own events for other plugins to receive using the register_events() plugin hook , combined with calls to the datasette.track_event() internal method .", "breadcrumbs": "[\"Plugin hooks\"]", "references": "[]"} {"id": "plugin_hooks:plugin-hook-extra-body-script", "page": "plugin_hooks", "ref": "plugin-hook-extra-body-script", "title": "extra_body_script(template, database, table, columns, view_name, request, datasette)", "content": "Extra JavaScript to be added to a element: \n @hookimpl\ndef extra_body_script():\n return {\n \"module\": True,\n \"script\": \"console.log('Your JavaScript goes here...')\",\n } \n This will add the following to the end of your page: \n \n Example: datasette-cluster-map", "breadcrumbs": "[\"Plugin hooks\", \"Page extras\"]", "references": "[{\"href\": \"https://datasette.io/plugins/datasette-cluster-map\", \"label\": \"datasette-cluster-map\"}]"} {"id": "plugin_hooks:plugin-hook-extra-template-vars", "page": "plugin_hooks", "ref": "plugin-hook-extra-template-vars", "title": "extra_template_vars(template, database, table, columns, view_name, request, datasette)", "content": "Extra template variables that should be made available in the rendered template context. \n \n \n template - string \n \n The template that is being rendered, e.g. database.html \n \n \n \n database - string or None \n \n The name of the database, or None if the page does not correspond to a database (e.g. the root page) \n \n \n \n table - string or None \n \n The name of the table, or None if the page does not correct to a table \n \n \n \n columns - list of strings or None \n \n The names of the database columns that will be displayed on this page. None if the page does not contain a table. \n \n \n \n view_name - string \n \n The name of the view being displayed. ( index , database , table , and row are the most important ones.) \n \n \n \n request - Request object or None \n \n The current HTTP request. This can be None if the request object is not available. \n \n \n \n datasette - Datasette class \n \n You can use this to access plugin configuration options via datasette.plugin_config(your_plugin_name) \n \n \n \n This hook can return one of three different types: \n \n \n Dictionary \n \n If you return a dictionary its keys and values will be merged into the template context. \n \n \n \n Function that returns a dictionary \n \n If you return a function it will be executed. If it returns a dictionary those values will will be merged into the template context. \n \n \n \n Function that returns an awaitable function that returns a dictionary \n \n You can also return a function which returns an awaitable function which returns a dictionary. \n \n \n \n Datasette runs Jinja2 in async mode , which means you can add awaitable functions to the template scope and they will be automatically awaited when they are rendered by the template. \n Here's an example plugin that adds a \"user_agent\" variable to the template context containing the current request's User-Agent header: \n @hookimpl\ndef extra_template_vars(request):\n return {\"user_agent\": request.headers.get(\"user-agent\")} \n This example returns an awaitable function which adds a list of hidden_table_names to the context: \n @hookimpl\ndef extra_template_vars(datasette, database):\n async def hidden_table_names():\n if database:\n db = datasette.databases[database]\n return {\n \"hidden_table_names\": await db.hidden_table_names()\n }\n else:\n return {}\n\n return hidden_table_names \n And here's an example which adds a sql_first(sql_query) function which executes a SQL statement and returns the first column of the first row of results: \n @hookimpl\ndef extra_template_vars(datasette, database):\n async def sql_first(sql, dbname=None):\n dbname = (\n dbname\n or database\n or next(iter(datasette.databases.keys()))\n )\n result = await datasette.execute(dbname, sql)\n return result.rows[0][0]\n\n return {\"sql_first\": sql_first} \n You can then use the new function in a template like so: \n SQLite version: {{ sql_first(\"select sqlite_version()\") }} \n Examples: datasette-search-all , datasette-template-sql", "breadcrumbs": "[\"Plugin hooks\", \"Page extras\"]", "references": "[{\"href\": \"https://jinja.palletsprojects.com/en/2.10.x/api/#async-support\", \"label\": \"async mode\"}, {\"href\": \"https://datasette.io/plugins/datasette-search-all\", \"label\": \"datasette-search-all\"}, {\"href\": \"https://datasette.io/plugins/datasette-template-sql\", \"label\": \"datasette-template-sql\"}]"} {"id": "plugin_hooks:plugin-register-permissions", "page": "plugin_hooks", "ref": "plugin-register-permissions", "title": "register_permissions(datasette)", "content": "If your plugin needs to register additional permissions unique to that plugin - upload-csvs for example - you can return a list of those permissions from this hook. \n from datasette import hookimpl, Permission\n\n\n@hookimpl\ndef register_permissions(datasette):\n return [\n Permission(\n name=\"upload-csvs\",\n abbr=None,\n description=\"Upload CSV files\",\n takes_database=True,\n takes_resource=False,\n default=False,\n )\n ] \n The fields of the Permission class are as follows: \n \n \n name - string \n \n The name of the permission, e.g. upload-csvs . This should be unique across all plugins that the user might have installed, so choose carefully. \n \n \n \n abbr - string or None \n \n An abbreviation of the permission, e.g. uc . This is optional - you can set it to None if you do not want to pick an abbreviation. Since this needs to be unique across all installed plugins it's best not to specify an abbreviation at all. If an abbreviation is provided it will be used when creating restricted signed API tokens. \n \n \n \n description - string or None \n \n A human-readable description of what the permission lets you do. Should make sense as the second part of a sentence that starts \"A user with this permission can ...\". \n \n \n \n takes_database - boolean \n \n True if this permission can be granted on a per-database basis, False if it is only valid at the overall Datasette instance level. \n \n \n \n takes_resource - boolean \n \n True if this permission can be granted on a per-resource basis. A resource is a database table, SQL view or canned query . \n \n \n \n default - boolean \n \n The default value for this permission if it is not explicitly granted to a user. True means the permission is granted by default, False means it is not. \n This should only be True if you want anonymous users to be able to take this action.", "breadcrumbs": "[\"Plugin hooks\"]", "references": "[]"} {"id": "plugin_hooks:plugin-hook-render-cell", "page": "plugin_hooks", "ref": "plugin-hook-render-cell", "title": "render_cell(row, value, column, table, database, datasette, request)", "content": "Lets you customize the display of values within table cells in the HTML table view. \n \n \n row - sqlite.Row \n \n The SQLite row object that the value being rendered is part of \n \n \n \n value - string, integer, float, bytes or None \n \n The value that was loaded from the database \n \n \n \n column - string \n \n The name of the column being rendered \n \n \n \n table - string or None \n \n The name of the table - or None if this is a custom SQL query \n \n \n \n database - string \n \n The name of the database \n \n \n \n datasette - Datasette class \n \n You can use this to access plugin configuration options via datasette.plugin_config(your_plugin_name) , or to execute SQL queries. \n \n \n \n request - Request object \n \n The current request object \n \n \n \n If your hook returns None , it will be ignored. Use this to indicate that your hook is not able to custom render this particular value. \n If the hook returns a string, that string will be rendered in the table cell. \n If you want to return HTML markup you can do so by returning a jinja2.Markup object. \n You can also return an awaitable function which returns a value. \n Datasette will loop through all available render_cell hooks and display the value returned by the first one that does not return None . \n Here is an example of a custom render_cell() plugin which looks for values that are a JSON string matching the following format: \n {\"href\": \"https://www.example.com/\", \"label\": \"Name\"} \n If the value matches that pattern, the plugin returns an HTML link element: \n from datasette import hookimpl\nimport markupsafe\nimport json\n\n\n@hookimpl\ndef render_cell(value):\n # Render {\"href\": \"...\", \"label\": \"...\"} as link\n if not isinstance(value, str):\n return None\n stripped = value.strip()\n if not (\n stripped.startswith(\"{\") and stripped.endswith(\"}\")\n ):\n return None\n try:\n data = json.loads(value)\n except ValueError:\n return None\n if not isinstance(data, dict):\n return None\n if set(data.keys()) != {\"href\", \"label\"}:\n return None\n href = data[\"href\"]\n if not (\n href.startswith(\"/\")\n or href.startswith(\"http://\")\n or href.startswith(\"https://\")\n ):\n return None\n return markupsafe.Markup(\n '{label}'.format(\n href=markupsafe.escape(data[\"href\"]),\n label=markupsafe.escape(data[\"label\"] or \"\")\n or \" \",\n )\n ) \n Examples: datasette-render-binary , datasette-render-markdown , datasette-json-html", "breadcrumbs": "[\"Plugin hooks\"]", "references": "[{\"href\": \"https://datasette.io/plugins/datasette-render-binary\", \"label\": \"datasette-render-binary\"}, {\"href\": \"https://datasette.io/plugins/datasette-render-markdown\", \"label\": \"datasette-render-markdown\"}, {\"href\": \"https://datasette.io/plugins/datasette-json-html\", \"label\": \"datasette-json-html\"}]"} {"id": "plugin_hooks:plugin-register-facet-classes", "page": "plugin_hooks", "ref": "plugin-register-facet-classes", "title": "register_facet_classes()", "content": "Return a list of additional Facet subclasses to be registered. \n \n The design of this plugin hook is unstable and may change. See issue 830 . \n \n Each Facet subclass implements a new type of facet operation. The class should look like this: \n class SpecialFacet(Facet):\n # This key must be unique across all facet classes:\n type = \"special\"\n\n async def suggest(self):\n # Use self.sql and self.params to suggest some facets\n suggested_facets = []\n suggested_facets.append(\n {\n \"name\": column, # Or other unique name\n # Construct the URL that will enable this facet:\n \"toggle_url\": self.ds.absolute_url(\n self.request,\n path_with_added_args(\n self.request, {\"_facet\": column}\n ),\n ),\n }\n )\n return suggested_facets\n\n async def facet_results(self):\n # This should execute the facet operation and return results, again\n # using self.sql and self.params as the starting point\n facet_results = []\n facets_timed_out = []\n facet_size = self.get_facet_size()\n # Do some calculations here...\n for column in columns_selected_for_facet:\n try:\n facet_results_values = []\n # More calculations...\n facet_results_values.append(\n {\n \"value\": value,\n \"label\": label,\n \"count\": count,\n \"toggle_url\": self.ds.absolute_url(\n self.request, toggle_path\n ),\n \"selected\": selected,\n }\n )\n facet_results.append(\n {\n \"name\": column,\n \"results\": facet_results_values,\n \"truncated\": len(facet_rows_results)\n > facet_size,\n }\n )\n except QueryInterrupted:\n facets_timed_out.append(column)\n\n return facet_results, facets_timed_out \n See datasette/facets.py for examples of how these classes can work. \n The plugin hook can then be used to register the new facet class like this: \n @hookimpl\ndef register_facet_classes():\n return [SpecialFacet]", "breadcrumbs": "[\"Plugin hooks\"]", "references": "[{\"href\": \"https://github.com/simonw/datasette/issues/830\", \"label\": \"issue 830\"}, {\"href\": \"https://github.com/simonw/datasette/blob/main/datasette/facets.py\", \"label\": \"datasette/facets.py\"}]"} {"id": "plugin_hooks:plugin-asgi-wrapper", "page": "plugin_hooks", "ref": "plugin-asgi-wrapper", "title": "asgi_wrapper(datasette)", "content": "Return an ASGI middleware wrapper function that will be applied to the Datasette ASGI application. \n This is a very powerful hook. You can use it to manipulate the entire Datasette response, or even to configure new URL routes that will be handled by your own custom code. \n You can write your ASGI code directly against the low-level specification, or you can use the middleware utilities provided by an ASGI framework such as Starlette . \n This example plugin adds a x-databases HTTP header listing the currently attached databases: \n from datasette import hookimpl\nfrom functools import wraps\n\n\n@hookimpl\ndef asgi_wrapper(datasette):\n def wrap_with_databases_header(app):\n @wraps(app)\n async def add_x_databases_header(\n scope, receive, send\n ):\n async def wrapped_send(event):\n if event[\"type\"] == \"http.response.start\":\n original_headers = (\n event.get(\"headers\") or []\n )\n event = {\n \"type\": event[\"type\"],\n \"status\": event[\"status\"],\n \"headers\": original_headers\n + [\n [\n b\"x-databases\",\n \", \".join(\n datasette.databases.keys()\n ).encode(\"utf-8\"),\n ]\n ],\n }\n await send(event)\n\n await app(scope, receive, wrapped_send)\n\n return add_x_databases_header\n\n return wrap_with_databases_header \n Examples: datasette-cors , datasette-pyinstrument , datasette-total-page-time", "breadcrumbs": "[\"Plugin hooks\"]", "references": "[{\"href\": \"https://asgi.readthedocs.io/\", \"label\": \"ASGI\"}, {\"href\": \"https://www.starlette.io/middleware/\", \"label\": \"Starlette\"}, {\"href\": \"https://datasette.io/plugins/datasette-cors\", \"label\": \"datasette-cors\"}, {\"href\": \"https://datasette.io/plugins/datasette-pyinstrument\", \"label\": \"datasette-pyinstrument\"}, {\"href\": \"https://datasette.io/plugins/datasette-total-page-time\", \"label\": \"datasette-total-page-time\"}]"} {"id": "plugin_hooks:plugin-hook-slots", "page": "plugin_hooks", "ref": "plugin-hook-slots", "title": "Template slots", "content": "The following set of plugin hooks can be used to return extra HTML content that will be inserted into the corresponding page, directly below the