{"id": "internals:internals-tilde-encoding", "page": "internals", "ref": "internals-tilde-encoding", "title": "Tilde encoding", "content": "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. \n                 Tilde encoding uses the same algorithm as  URL percent-encoding , but with the  ~  tilde character used in place of  % . \n                 Any character other than  ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz0123456789_-  will be replaced by the numeric equivalent preceded by a tilde. For example: \n                 \n                     \n                         /  becomes  ~2F \n                     \n                     \n                         .  becomes  ~2E \n                     \n                     \n                         %  becomes  ~25 \n                     \n                     \n                         ~  becomes  ~7E \n                     \n                     \n                         Space becomes  + \n                     \n                     \n                         polls/2022.primary  becomes  polls~2F2022~2Eprimary \n                     \n                 \n                 Note that the space character is a special case: it will be replaced with a  +  symbol. \n                 \n                 \n                 \n                     datasette.utils. tilde_encode s :   str str \n                     \n                         Returns tilde-encoded string - for example  /foo/bar  ->  ~2Ffoo~2Fbar \n                     \n                 \n                 \n                 \n                 \n                     datasette.utils. tilde_decode s :   str str \n                     \n                         Decodes a tilde-encoded string, so  ~2Ffoo~2Fbar  ->  /foo/bar", "breadcrumbs": "[\"Internals for plugins\", \"The datasette.utils module\"]", "references": "[{\"href\": \"https://developer.mozilla.org/en-US/docs/Glossary/percent-encoding\", \"label\": \"URL percent-encoding\"}]"}
{"id": "internals:internals-utils-await-me-maybe", "page": "internals", "ref": "internals-utils-await-me-maybe", "title": "await_me_maybe(value)", "content": "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 \u201cawait me maybe\u201d pattern for Python asyncio . \n                 \n                 \n                     async   datasette.utils. await_me_maybe value :   Any Any \n                     \n                         If value is callable, call it. If awaitable, await it. Otherwise return it.", "breadcrumbs": "[\"Internals for plugins\", \"The datasette.utils module\"]", "references": "[{\"href\": \"https://simonwillison.net/2020/Sep/2/await-me-maybe/\", \"label\": \"The \u201cawait me maybe\u201d pattern for Python asyncio\"}]"}
{"id": "internals:internals-utils-derive-named-parameters", "page": "internals", "ref": "internals-utils-derive-named-parameters", "title": "derive_named_parameters(db, sql)", "content": "Derive the list of named parameters referenced in a SQL query, using an  explain  query executed against the provided database. \n                 \n                 \n                     async   datasette.utils. derive_named_parameters db :   Database sql :   str List [ str ] \n                     \n                         Given a SQL statement, return a list of named parameters that are used in the statement \n                         e.g. for  select * from foo where id=:id  this would return  [\"id\"]", "breadcrumbs": "[\"Internals for plugins\", \"The datasette.utils module\"]", "references": "[]"}
{"id": "internals:internals-utils-parse-metadata", "page": "internals", "ref": "internals-utils-parse-metadata", "title": "parse_metadata(content)", "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. \n                 If the metadata cannot be parsed as either JSON or YAML the function will raise a  utils.BadMetadataError  exception. \n                 \n                 \n                     datasette.utils. parse_metadata content :   str dict \n                     \n                         Detects if content is JSON or YAML and parses it appropriately.", "breadcrumbs": "[\"Internals for plugins\", \"The datasette.utils module\"]", "references": "[]"}