{"id": "plugin_hooks:plugin-register-output-renderer", "page": "plugin_hooks", "ref": "plugin-register-output-renderer", "title": "register_output_renderer(datasette)", "content": "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             Registers a new output renderer, to output data in a custom format. The hook function should return a dictionary, or a list of dictionaries, of the following shape: \n             @hookimpl\ndef register_output_renderer(datasette):\n    return {\n        \"extension\": \"test\",\n        \"render\": render_demo,\n        \"can_render\": can_render_demo,  # Optional\n    } \n             This will register  render_demo  to be called when paths with the extension  .test  (for example  /database.test ,  /database/table.test , or  /database/table/row.test ) are requested. \n             render_demo  is a Python function. It can be a regular function or an  async def render_demo()  awaitable function, depending on if it needs to make any asynchronous calls. \n             can_render_demo  is a Python function (or  async def  function) which accepts the same arguments as  render_demo  but just returns  True  or  False . It lets Datasette know if the current SQL query can be represented by the plugin - and hence influence if a link to this output format is displayed in the user interface. If you omit the  \"can_render\"  key from the dictionary every query will be treated as being supported by the plugin. \n             When a request is received, the  \"render\"  callback function is called with zero or more of the following arguments. Datasette will inspect your callback function and pass arguments that match its function signature. \n             \n                 \n                     datasette  -  Datasette class \n                     \n                         For accessing plugin configuration and executing queries. \n                     \n                 \n                 \n                     columns  - list of strings \n                     \n                         The names of the columns returned by this query. \n                     \n                 \n                 \n                     rows  - list of  sqlite3.Row  objects \n                     \n                         The rows returned by the query. \n                     \n                 \n                 \n                     sql  - string \n                     \n                         The SQL query that was executed. \n                     \n                 \n                 \n                     query_name  - string or None \n                     \n                         If this was the execution of a  canned query , the name of that query. \n                     \n                 \n                 \n                     database  - string \n                     \n                         The name of the database. \n                     \n                 \n                 \n                     table  - string or None \n                     \n                         The table or view, if one is being rendered. \n                     \n                 \n                 \n                     request  -  Request object \n                     \n                         The current HTTP request. \n                     \n                 \n                 \n                     error  - string or None \n                     \n                         If an error occurred this string will contain the error message. \n                     \n                 \n                 \n                     truncated  - bool or None \n                     \n                         If the query response was truncated - for example a SQL query returning more than 1,000 results where pagination is not available - this will be  True . \n                     \n                 \n                 \n                     view_name  - string \n                     \n                         The name of the current view being called.  index ,  database ,  table , and  row  are the most important ones. \n                     \n                 \n             \n             The callback function can return  None , if it is unable to render the data, or a  Response class  that will be returned to the caller. \n             It can also return a dictionary with the following keys. This format is  deprecated  as-of Datasette 0.49 and will be removed by Datasette 1.0. \n             \n                 \n                     body  - string or bytes, optional \n                     \n                         The response body, default empty \n                     \n                 \n                 \n                     content_type  - string, optional \n                     \n                         The Content-Type header, default  text/plain \n                     \n                 \n                 \n                     status_code  - integer, optional \n                     \n                         The HTTP status code, default 200 \n                     \n                 \n                 \n                     headers  - dictionary, optional \n                     \n                         Extra HTTP headers to be returned in the response. \n                     \n                 \n             \n             An example of an output renderer callback function: \n             def render_demo():\n    return Response.text(\"Hello World\") \n             Here is a more complex example: \n             async def render_demo(datasette, columns, rows):\n    db = datasette.get_database()\n    result = await db.execute(\"select sqlite_version()\")\n    first_row = \" | \".join(columns)\n    lines = [first_row]\n    lines.append(\"=\" * len(first_row))\n    for row in rows:\n        lines.append(\" | \".join(row))\n    return Response(\n        \"\\n\".join(lines),\n        content_type=\"text/plain; charset=utf-8\",\n        headers={\"x-sqlite-version\": result.first()[0]},\n    ) \n             And here is an example  can_render  function which returns  True  only if the query results contain the columns  atom_id ,  atom_title  and  atom_updated : \n             def can_render_demo(columns):\n    return {\n        \"atom_id\",\n        \"atom_title\",\n        \"atom_updated\",\n    }.issubset(columns) \n             Examples:  datasette-atom ,  datasette-ics ,  datasette-geojson ,  datasette-copyable", "breadcrumbs": "[\"Plugin hooks\"]", "references": "[{\"href\": \"https://datasette.io/plugins/datasette-atom\", \"label\": \"datasette-atom\"}, {\"href\": \"https://datasette.io/plugins/datasette-ics\", \"label\": \"datasette-ics\"}, {\"href\": \"https://datasette.io/plugins/datasette-geojson\", \"label\": \"datasette-geojson\"}, {\"href\": \"https://datasette.io/plugins/datasette-copyable\", \"label\": \"datasette-copyable\"}]"}