id,page,ref,title,content,breadcrumbs,references
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-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-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.
len(request.args) - integer
Returns the number of keys.","[""Internals for plugins""]",[]
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(
""