.. _searchformat:
.. currentmodule:: flask.ext.restless
Making search queries
=====================
Clients can make :http:method:`get` requests on individual instances of a model
(for example, :http:get:`/api/person/1`) and on collections of all instances of
a model (:http:get:`/api/person`). To get all instances of a model that meet
some criteria, clients can make :http:method:`get` requests with a query
parameter specifying a search. The search functionality in Flask-Restless is
relatively simple, but should suffice for many cases.
Quick examples
--------------
The following are some quick examples of creating search queries with different
types of clients. Find more complete documentation in subsequent sections. In
these examples, each client will search for instances of the model ``Person``
whose names contain the letter "y".
Using the Python `requests `_
library::
import requests
import json
url = 'http://127.0.0.1:5000/api/person'
headers = {'Content-Type': 'application/json'}
filters = [dict(name='name', op='like', val='%y%')]
params = dict(q=json.dumps(dict(filters=filters)))
response = requests.get(url, params=params, headers=headers)
assert response.status_code == 200
print(response.json())
Using `jQuery `_:
.. sourcecode:: javascript
var filters = [{"name": "id", "op": "like", "val": "%y%"}];
$.ajax({
url: 'http://127.0.0.1:5000/api/person',
data: {"q": JSON.stringify({"filters": filters})},
dataType: "json",
contentType: "application/json",
success: function(data) { console.log(data.objects); }
});
Using `curl `_:
.. sourcecode:: bash
curl \
-G \
-H "Content-type: application/json" \
-d "q={\"filters\":[{\"name\":\"name\",\"op\":\"like\",\"val\":\"%y%\"}]}" \
http://127.0.0.1:5000/api/person
The ``examples/`` directory has more complete versions of these examples.
.. _queryformat:
Query format
------------
The query parameter ``q`` must be a JSON string. It can have the following
mappings, all of which are optional:
``filters``
A list of objects of one of the following forms::
{"name": , "op": , "val": }
or::
{"name": , "op": , "field": }
In the first form, ```` is one of the strings described in the
:ref:`operators` section, the first ```` is the name of the field
of the model to which to apply the operator, ```` is a value to be
used as the second argument to the given operator. In the second form, the
second ```` is the field of the model that should be used as the
second argument to the operator.
```` may alternately specify a field on a related model, if it is
a string of the form ``__``.
If the field name is the name of a relation and the operator is ``"has"`` or
``"any"``, the ``"val"`` argument can be a dictionary with the arguments
representing another filter to be applied as the argument for ``"has"`` or
``"any"``.
The returned list of matching instances will include only those instances
that satisfy all of the given filters.
``disjunction``
A Boolean that specifies whether the list of filters should be treated as a
disjunction or a conjunction. If this is ``true``, the response will include
all instances of the model that match *any* of the filters. If this is
``false`` the response will include all instances of the model that match
*all* of the filters. This will be treated as ``false`` if not specified by
the client (in other words, the default is conjunction).
``limit``
A positive integer which specifies the maximum number of objects to return.
``offset``
A positive integer which specifies the offset into the result set of the
returned list of instances.
``order_by``
A list of objects of the form::
{"field": , "direction": }
where ```` is a string corresponding to the name of a field of the
requested model and ```` is either ``"asc"`` for ascending
order or ``"desc"`` for descending order.
``single``
A Boolean representing whether a single result is expected as a result of the
search. If this is ``true`` and either no results or multiple results meet
the criteria of the search, the server responds with an error message.
If a filter is poorly formatted (for example, ``op`` is set to ``'=='`` but
``val`` is not set), the server responds with :http:statuscode:`400`.
.. _operators:
Operators
---------
The operator strings recognized by the API incude:
* ``==``, ``eq``, ``equals``, ``equals_to``
* ``!=``, ``neq``, ``does_not_equal``, ``not_equal_to``
* ``>``, ``gt``, ``<``, ``lt``
* ``>=``, ``ge``, ``gte``, ``geq``, ``<=``, ``le``, ``lte``, ``leq``
* ``in``, ``not_in``
* ``is_null``, ``is_not_null``
* ``like``
* ``has``
* ``any``
These correspond to SQLAlchemy column operators as defined `here
`_.
Examples
--------
Consider a ``Person`` model available at the URL ``/api/person``, and suppose
all of the following requests are :http:get:`/api/person` requests with query
parameter ``q``.
Attribute greater than a value
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
On request:
.. sourcecode:: http
GET /api/person?q={"filters":[{"name":"age","op":"ge","val":10}]} HTTP/1.1
Host: example.com
the response will include only those ``Person`` instances that have ``age``
attribute greater than or equal to 10:
.. sourcecode:: http
HTTP/1.1 200 OK
{
"num_results": 8,
"total_pages": 3,
"page": 2,
"objects":
[
{"id": 1, "name": "Jeffrey", "age": 24},
{"id": 2, "name": "John", "age": 13},
{"id": 3, "name": "Mary", "age": 18}
]
}
Disjunction of filters
~~~~~~~~~~~~~~~~~~~~~~
On request:
.. sourcecode:: http
GET /api/person?q={"filters":[{"name":"age","op":"lt","val":10},{"name":"age","op":"gt","val":20}],"disjunction":true} HTTP/1.1
Host: example.com
the response will include only those ``Person`` instances that have ``age``
attribute either less than 10 or greater than 20:
.. sourcecode:: http
HTTP/1.1 200 OK
{
"num_results": 3,
"total_pages": 1,
"page": 1,
"objects":
[
{"id": 4, "name": "Abraham", "age": 9},
{"id": 5, "name": "Isaac", "age": 25},
{"id": 6, "name": "Job", "age": 37}
]
}
Attribute between two values
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
On request:
.. sourcecode:: http
GET /api/person?q={"filters":[{"name":"age","op":"ge","val":10},{"name":"age","op":"le","val":20}]} HTTP/1.1
Host: example.com
the response will include only those ``Person`` instances that have ``age``
attribute between 10 and 20, inclusive:
.. sourcecode:: http
HTTP/1.1 200 OK
{
"num_results": 6,
"total_pages": 3,
"page": 2,
"objects":
[
{"id": 2, "name": "John", "age": 13},
{"id": 3, "name": "Mary", "age": 18}
]
}
Expecting a single result
~~~~~~~~~~~~~~~~~~~~~~~~~
On request:
.. sourcecode:: javascript
GET /api/person?q={"filters":[{"name":"id","op":"eq","val":1}],"single":true} HTTP/1.1
Host: example.com
the response will include only the sole ``Person`` instance with ``id`` equal
to 1:
.. sourcecode:: http
HTTP/1.1 200 OK
{"id": 1, "name": "Jeffrey", "age": 24}
In the case that the search would return no results or more than one result, an
error response is returned instead:
.. sourcecode:: http
GET /api/person?q={"filters":[{"name":"age","op":"ge","val":10}],"single":true} HTTP/1.1
Host: example.com
.. sourcecode:: http
HTTP/1.1 400 Bad Request
{"message": "Multiple results found"}
.. sourcecode:: http
GET /api/person?q={"filters":[{"name":"id","op":"eq","val":-1}],"single":true} HTTP/1.1
Host: example.com
.. sourcecode:: http
HTTP/1.1 404 Bad Request
{"message": "No result found"}
Comparing two attributes
~~~~~~~~~~~~~~~~~~~~~~~~
On request:
.. sourcecode:: http
GET /api/person?q={"filters":[{"name":"age","op":"ge","field":"height"}]} HTTP/1.1
Host: example.com
the response will include only those ``Person`` instances that have ``age``
attribute greater than or equal to the value of the ``height`` attribute:
.. sourcecode:: http
HTTP/1.1 200 OK
{
"num_results": 6,
"total_pages": 3,
"page": 2,
"objects":
[
{"id": 1, "name": "John", "age": 80, "height": 65},
{"id": 2, "name": "Mary", "age": 73, "height": 60}
]
}
Comparing attribute of a relation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
On request:
.. sourcecode:: http
GET /api/person?q={"filters":[{"name":"computers__manufacturer","op":"any","val":"Apple"}],"single":true} HTTP/1.1
Host: example.com
response will include only those ``Person`` instances that are related to any
``Computer`` model that is manufactured by Apple:
.. sourcecode:: http
HTTP/1.1 200 OK
{
"num_results": 6,
"total_pages": 3,
"page": 2,
"objects":
{
"id": 1,
"name": "John",
"computers": [
{ "id": 1, "manufacturer": "Dell", "model": "Inspiron 9300"},
{ "id": 2, "manufacturer": "Apple", "model": "MacBook"}
]
},
{
"id": 2,
"name": "Mary",
"computers": [
{ "id": 3, "manufacturer": "Apple", "model": "iMac"}
]
}
]
}
Using ``has`` and ``any``
~~~~~~~~~~~~~~~~~~~~~~~~~
On request:
.. sourcecode:: http
GET /api/person?q={"filters":[{"name":"computers","op":"any","val":{"name":"id","op":"gt","val":1}}]} HTTP/1.1
Host: example.com
the response will include only those ``Person`` instances that have a related
``Computer`` instance with ``id`` field of value greater than 1:
.. sourcecode:: http
HTTP/1.1 200 OK
{
"num_results": 6,
"total_pages": 3,
"page": 2,
"objects":
[
{"id": 1, "name": "John", "age": 80, "height": 65, "computers": [...]},
{"id": 2, "name": "Mary", "age": 73, "height": 60, "computers": [...]}
]
}