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Interacting With The API

Now that you've got a shiny new REST-style API in place, let's demonstrate how to interact with it. We'll assume that you have cURL installed on your system (generally available on most modern Mac & Linux machines), but any tool that allows you to control headers & bodies on requests will do.

We'll assume that we're interacting with the following Tastypie code:

# myapp/api/resources.py
from django.contrib.auth.models import User
from tastypie.authorization import Authorization
from tastypie import fields
from tastypie.resources import ModelResource, ALL, ALL_WITH_RELATIONS
from myapp.models import Entry


class UserResource(ModelResource):
    class Meta:
        queryset = User.objects.all()
        resource_name = 'user'
        excludes = ['email', 'password', 'is_active', 'is_staff', 'is_superuser']
        filtering = {
            'username': ALL,
        }


class EntryResource(ModelResource):
    user = fields.ForeignKey(UserResource, 'user')

    class Meta:
        queryset = Entry.objects.all()
        resource_name = 'entry'
        authorization = Authorization()
        filtering = {
            'user': ALL_WITH_RELATIONS,
            'pub_date': ['exact', 'lt', 'lte', 'gte', 'gt'],
        }


# urls.py
from django.conf.urls import url, include
from tastypie.api import Api
from myapp.api.resources import EntryResource, UserResource

v1_api = Api(api_name='v1')
v1_api.register(UserResource())
v1_api.register(EntryResource())

urlpatterns = [
    # The normal jazz here...
    url(r'^blog/', include('myapp.urls')),
    url(r'^api/', include(v1_api.urls)),
]

Let's fire up a shell & start exploring the API!

Front Matter

Tastypie tries to treat all clients & all serialization types as equally as possible. It also tries to be a good 'Net citizen & respects the HTTP method used as well as the Accepts headers sent. Between these two, you control all interactions with Tastypie through relatively few endpoints.

Warning

Should you try these URLs in your browser, be warned you WILL need to append ?format=json (or xml or yaml) to the URL. Your browser requests application/xml before application/json, so you'll always get back XML if you don't specify it.

That's also why it's recommended that you explore via curl, because you avoid your browser's opinionated requests & get something closer to what any programmatic clients will get.

Fetching Data

Since reading data out of an API is a very common activity (and the easiest type of request to make), we'll start there. Tastypie tries to expose various parts of the API & interlink things within the API (HATEOAS).

Api-Wide

We'll start at the highest level:

curl http://localhost:8000/api/v1/

You'll get back something like:

{
    "entry": {
        "list_endpoint": "/api/v1/entry/",
        "schema": "/api/v1/entry/schema/"
    },
    "user": {
        "list_endpoint": "/api/v1/user/",
        "schema": "/api/v1/user/schema/"
    }
}

This lists out all the different Resource classes you registered in your URLconf with the API. Each one is listed by the resource_name you gave it and provides the list_endpoint & the schema for the resource.

Note that these links try to direct you to other parts of the API, to make exploration/discovery easier. We'll use these URLs in the next several sections.

To demonstrate another format, you could run the following to get the XML variant of the same information:

curl -H "Accept: application/xml" http://localhost:8000/api/v1/

To which you'd receive:

<?xml version="1.0" encoding="utf-8"?>
<response>
  <entry type="hash">
    <list_endpoint>/api/v1/entry/</list_endpoint>
    <schema>/api/v1/entry/schema/</schema>
  </entry>
  <user type="hash">
    <list_endpoint>/api/v1/user/</list_endpoint>
    <schema>/api/v1/user/schema/</schema>
  </user>
</response>

We'll stick to JSON for the rest of this document, but using XML should be OK to do at any time.

It's also possible to get all schemas (Inspecting The Resource's Schema) in a single request:

curl http://localhost:8000/api/v1/?fullschema=true

You'll get back something like:

{
    "entry": {
        "list_endpoint": "/api/v1/entry/",
        "schema": {
            "default_format": "application/json",
            "fields": {
                "body": {
                    "help_text": "Unicode string data. Ex: \"Hello World\"",
                    "nullable": false,
                    "readonly": false,
                    "type": "string"
                },
                ...
            },
            "filtering": {
                "pub_date": ["exact", "lt", "lte", "gte", "gt"],
                "user": 2
            }
        }
    },
}

Inspecting The Resource's Schema

Since the api-wide view gave us a schema URL, let's inspect that next. We'll use the entry resource. Again, a simple GET request by curl:

curl http://localhost:8000/api/v1/entry/schema/

This time, we get back a lot more data:

{
    "default_format": "application/json",
    "fields": {
        "body": {
            "help_text": "Unicode string data. Ex: \"Hello World\"",
            "nullable": false,
            "readonly": false,
            "type": "string"
        },
        "id": {
            "help_text": "Unicode string data. Ex: \"Hello World\"",
            "nullable": false,
            "readonly": false,
            "type": "string"
        },
        "pub_date": {
            "help_text": "A date & time as a string. Ex: \"2010-11-10T03:07:43\"",
            "nullable": false,
            "readonly": false,
            "type": "datetime"
        },
        "resource_uri": {
            "help_text": "Unicode string data. Ex: \"Hello World\"",
            "nullable": false,
            "readonly": true,
            "type": "string"
        },
        "slug": {
            "help_text": "Unicode string data. Ex: \"Hello World\"",
            "nullable": false,
            "readonly": false,
            "type": "string"
        },
        "title": {
            "help_text": "Unicode string data. Ex: \"Hello World\"",
            "nullable": false,
            "readonly": false,
            "type": "string"
        },
        "user": {
            "help_text": "A single related resource. Can be either a URI or set of nested resource data.",
            "nullable": false,
            "readonly": false,
            "type": "related"
            "related_type": "to_one"
            "related_schema": "/api/v1/user/schema/"
        }
    },
    "filtering": {
        "pub_date": ["exact", "lt", "lte", "gte", "gt"],
        "user": 2
    }
}

This lists out the default_format this resource responds with, the fields on the resource & the filtering options available. This information can be used to prepare the other aspects of the code for the data it can obtain & ways to filter the resources.

Getting A Collection Of Resources

Let's get down to fetching live data. From the api-wide view, we'll hit the list_endpoint for entry:

curl http://localhost:8000/api/v1/entry/

We get back data that looks like:

{
    "meta": {
        "limit": 20,
        "next": null,
        "offset": 0,
        "previous": null,
        "total_count": 3
    },
    "objects": [{
        "body": "Welcome to my blog!",
        "id": "1",
        "pub_date": "2011-05-20T00:46:38",
        "resource_uri": "/api/v1/entry/1/",
        "slug": "first-post",
        "title": "First Post",
        "user": "/api/v1/user/1/"
    },
    {
        "body": "Well, it's been awhile and I still haven't updated. ",
        "id": "2",
        "pub_date": "2011-05-21T00:46:58",
        "resource_uri": "/api/v1/entry/2/",
        "slug": "second-post",
        "title": "Second Post",
        "user": "/api/v1/user/1/"
    },
    {
        "body": "I'm really excited to get started with this new blog. It's gonna be great!",
        "id": "3",
        "pub_date": "2011-05-20T00:47:30",
        "resource_uri": "/api/v1/entry/3/",
        "slug": "my-blog",
        "title": "My Blog",
        "user": "/api/v1/user/2/"
    }]
}

Some things to note:

  • By default, you get a paginated set of objects (20 per page is the default).
  • In the meta, you get a previous & next. If available, these are URIs to the previous & next pages.
  • You get a list of resources/objects under the objects key.
  • Each resources/object has a resource_uri field that points to the detail view for that object.
  • The foreign key to User is represented as a URI by default. If you're looking for the full UserResource to be embedded in this view, you'll need to add full=True to the fields.ToOneField.

If you want to skip paginating, simply run:

curl http://localhost:8000/api/v1/entry/?limit=0

Be warned this will return all objects, so it may be a CPU/IO-heavy operation on large datasets.

Let's try filtering on the resource. Since we know we can filter on the user, we'll fetch all posts by the daniel user with:

curl http://localhost:8000/api/v1/entry/?user__username=daniel

We get back what we asked for:

{
    "meta": {
        "limit": 20,
        "next": null,
        "offset": 0,
        "previous": null,
        "total_count": 2
    },
    "objects": [{
        "body": "Welcome to my blog!",
        "id": "1",
        "pub_date": "2011-05-20T00:46:38",
        "resource_uri": "/api/v1/entry/1/",
        "slug": "first-post",
        "title": "First Post",
        "user": "/api/v1/user/1/"
    },
    {
        "body": "Well, it's been awhile and I still haven't updated. ",
        "id": "2",
        "pub_date": "2011-05-21T00:46:58",
        "resource_uri": "/api/v1/entry/2/",
        "slug": "second-post",
        "title": "Second Post",
        "user": "/api/v1/user/1/"
    }]
}

Where there were three posts before, now there are only two.

Getting A Detail Resource

Since each resource/object in the list view had a resource_uri, let's explore what's there:

curl http://localhost:8000/api/v1/entry/1/

We get back a similar set of data that we received from the list view:

{
    "body": "Welcome to my blog!",
    "id": "1",
    "pub_date": "2011-05-20T00:46:38",
    "resource_uri": "/api/v1/entry/1/",
    "slug": "first-post",
    "title": "First Post",
    "user": "/api/v1/user/1/"
}

Where this proves useful (for example) is present in the data we got back. We know the URI of the User associated with this blog entry. Let's run:

curl http://localhost:8000/api/v1/user/1/

Without ever seeing any aspect of the UserResource & just following the URI given, we get back:

{
    "date_joined": "2011-05-20T00:42:14.990617",
    "first_name": "",
    "id": "1",
    "last_login": "2011-05-20T00:44:57.510066",
    "last_name": "",
    "resource_uri": "/api/v1/user/1/",
    "username": "daniel"
}

You can do a similar fetch using the following Javascript/jQuery (though be wary of same-domain policy):

$.ajax({
  url: 'http://localhost:8000/api/v1/user/1/',
  type: 'GET',
  accepts: 'application/json',
  dataType: 'json'
})

Selecting A Subset Of Resources

Sometimes you may want back more than one record, but not an entire list view nor do you want to do multiple requests. Tastypie includes a "set" view, which lets you cherry-pick the objects you want. For example, if we just want the first & third Entry resources, we'd run:

curl "http://localhost:8000/api/v1/entry/set/1;3/"

Note

Quotes are needed in this case because of the semicolon delimiter between primary keys. Without the quotes, bash tries to split it into two statements. No extraordinary quoting will be necessary in your application (unless your API client is written in bash :D).

And we get back just those two objects:

{
    "objects": [{
        "body": "Welcome to my blog!",
        "id": "1",
        "pub_date": "2011-05-20T00:46:38",
        "resource_uri": "/api/v1/entry/1/",
        "slug": "first-post",
        "title": "First Post",
        "user": "/api/v1/user/1/"
    },
    {
        "body": "I'm really excited to get started with this new blog. It's gonna be great!",
        "id": "3",
        "pub_date": "2011-05-20T00:47:30",
        "resource_uri": "/api/v1/entry/3/",
        "slug": "my-blog",
        "title": "My Blog",
        "user": "/api/v1/user/2/"
    }]
}

Note that, like the list view, you get back a list of objects. Unlike the list view, there is NO pagination applied to these objects. You asked for them, you're going to get them all.

Sending Data

Tastypie also gives you full write capabilities in the API. Since the EntryResource has the no-limits Authentication & Authorization on it, we can freely write data.

Warning

Note that this is a huge security hole as well. Don't put unauthorized write-enabled resources on the Internet, because someone will trash your data.

This is why ReadOnlyAuthorization is the default in Tastypie & why you must override to provide more access.

The good news is that there are no new URLs to learn. The "list" & "detail" URLs we've been using to fetch data ALSO support the POST/PUT/DELETE HTTP methods.

Creating A New Resource (POST)

Let's add a new entry. To create new data, we'll switch from GET requests to the familiar POST request.

Note

Tastypie encourages "round-trippable" data, which means the data you can GET should be able to be POST/PUT'd back to recreate the same object.

If you're ever in question about what you should send, do a GET on another object & see what Tastypie thinks it should look like.

To create new resources/objects, you will POST to the list endpoint of a resource. Trying to POST to a detail endpoint has a different meaning in the REST mindset (meaning to add a resource as a child of a resource of the same type).

As with all Tastypie requests, the headers we request are important. Since we've been using primarily JSON throughout, let's send a new entry in JSON format:

curl --dump-header - -H "Content-Type: application/json" -X POST --data '{"body": "This will prbbly be my lst post.", "pub_date": "2011-05-22T00:46:38", "slug": "another-post", "title": "Another Post", "user": "/api/v1/user/1/"}' http://localhost:8000/api/v1/entry/

The Content-Type header here informs Tastypie that we're sending it JSON. We send the data as a JSON-serialized body (NOT as form-data in the form of URL parameters). What we get back is the following response:

HTTP/1.0 201 CREATED
Date: Fri, 20 May 2011 06:48:36 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Type: text/html; charset=utf-8
Location: http://localhost:8000/api/v1/entry/4/

You'll also note that we get a correct HTTP status code back (201) & a Location header, which gives us the URI to our newly created resource.

Passing --dump-header - is important, because it gives you all the headers as well as the status code. When things go wrong, this will be useful information to help with debugging. For instance, if we send a request without a user:

curl --dump-header - -H "Content-Type: application/json" -X POST --data '{"body": "This will prbbly be my lst post.", "pub_date": "2011-05-22T00:46:38", "slug": "another-post", "title": "Another Post"}' http://localhost:8000/api/v1/entry/

We get back:

HTTP/1.0 400 BAD REQUEST
Date: Fri, 20 May 2011 06:53:02 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Type: text/html; charset=utf-8

The 'user' field has no data and doesn't allow a default or null value.

You can do a similar POST using the following Javascript/jQuery (though be wary of same-domain policy):

# This may require the ``json2.js`` library for older browsers.
var data = JSON.stringify({
    "body": "This will prbbly be my lst post.",
    "pub_date": "2011-05-22T00:46:38",
    "slug": "another-post",
    "title": "Another Post"
});

$.ajax({
  url: 'http://localhost:8000/api/v1/entry/',
  type: 'POST',
  contentType: 'application/json',
  data: data,
  dataType: 'json',
  processData: false
})

Updating An Existing Resource (PUT)

You might have noticed that we made some typos when we submitted the POST request. We can fix this using a PUT request to the detail endpoint (modify this instance of a resource).:

curl --dump-header - -H "Content-Type: application/json" -X PUT --data '{"body": "This will probably be my last post.", "pub_date": "2011-05-22T00:46:38", "slug": "another-post", "title": "Another Post", "user": "/api/v1/user/1/"}' http://localhost:8000/api/v1/entry/4/

After fixing up the body, we get back:

HTTP/1.0 204 NO CONTENT
Date: Fri, 20 May 2011 07:13:21 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Length: 0
Content-Type: text/html; charset=utf-8

We get a 204 status code, meaning our update was successful. We don't get a Location header back because we did the PUT on a detail URL, which presumably did not change.

Note

A PUT request requires that the entire resource representation be enclosed. Missing fields may cause errors, or be filled in by default values.

Partially Updating An Existing Resource (PATCH)

In some cases, you may not want to send the entire resource when updating. To update just a subset of the fields, we can send a PATCH request to the detail endpoint.:

curl --dump-header - -H "Content-Type: application/json" -X PATCH --data '{"body": "This actually is my last post."}' http://localhost:8000/api/v1/entry/4/

To which we should get back:

HTTP/1.0 202 ACCEPTED
Date: Fri, 20 May 2011 07:13:21 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Length: 0
Content-Type: text/html; charset=utf-8

Updating A Whole Collection Of Resources (PUT)

You can also, in rare circumstances, update an entire collection of objects. By sending a PUT request to the list view of a resource, you can replace the entire collection.

Warning

This deletes all of the objects first, then creates the objects afresh. This is done because determining which objects are the same is actually difficult to get correct in the general case for all people.

Send a request like:

curl --dump-header - -H "Content-Type: application/json" -X PUT --data '{"objects": [{"body": "Welcome to my blog!","id": "1","pub_date": "2011-05-20T00:46:38","resource_uri": "/api/v1/entry/1/","slug": "first-post","title": "First Post","user": "/api/v1/user/1/"},{"body": "I'm really excited to get started with this new blog. It's gonna be great!","id": "3","pub_date": "2011-05-20T00:47:30","resource_uri": "/api/v1/entry/3/","slug": "my-blog","title": "My Blog","user": "/api/v1/user/2/"}]}' http://localhost:8000/api/v1/entry/

And you'll get back a response like:

HTTP/1.0 204 NO CONTENT
Date: Fri, 20 May 2011 07:13:21 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Length: 0
Content-Type: text/html; charset=utf-8

Deleting Data

No CRUD setup would be complete without the ability to delete resources/objects. Deleting also requires significantly less complicated requests than POST/PUT.

Deleting A Single Resource

We've decided that we don't like the entry we added & edited earlier. Let's delete it (but leave the other objects alone):

curl --dump-header - -H "Content-Type: application/json" -X DELETE  http://localhost:8000/api/v1/entry/4/

Once again, we get back the "Accepted" response of a 204:

HTTP/1.0 204 NO CONTENT
Date: Fri, 20 May 2011 07:28:01 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Length: 0
Content-Type: text/html; charset=utf-8

If we request that resource, we get a 404 to show it's no longer there:

curl --dump-header - http://localhost:8000/api/v1/entry/4/

HTTP/1.0 404 GONE
Date: Fri, 20 May 2011 07:29:02 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Type: text/html; charset=utf-8

Additionally, if we try to run the DELETE again (using the same original command), we get the "Gone" response again:

HTTP/1.0 404 GONE
Date: Fri, 20 May 2011 07:30:00 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Type: text/html; charset=utf-8

Deleting A Whole Collection Of Resources

Finally, it's possible to remove an entire collection of resources. This is as destructive as it sounds. Once again, we use the DELETE method, this time on the entire list endpoint:

curl --dump-header - -H "Content-Type: application/json" -X DELETE  http://localhost:8000/api/v1/entry/

As a response, we get:

HTTP/1.0 204 NO CONTENT
Date: Fri, 20 May 2011 07:32:51 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Length: 0
Content-Type: text/html; charset=utf-8

Hitting the list view:

curl --dump-header - http://localhost:8000/api/v1/entry/

Gives us a 200 but no objects:

{
    "meta": {
        "limit": 20,
        "next": null,
        "offset": 0,
        "previous": null,
        "total_count": 0
    },
    "objects": []
}

Bulk Operations

As an optimization, it is possible to do many creations, updates, and deletions to a collection in a single request by sending a PATCH to the list endpoint.:

curl --dump-header - -H "Content-Type: application/json" -X PATCH --data '{"objects": [{"body": "Surprise! Another post!.", "pub_date": "2012-02-16T00:46:38", "slug": "yet-another-post", "title": "Yet Another Post"}], "deleted_objects": ["http://localhost:8000/api/v1/entry/4/"]}'  http://localhost:8000/api/v1/entry/

We should get back:

HTTP/1.0 202 ACCEPTED
Date: Fri, 16 Feb 2012 00:46:38 GMT
Server: WSGIServer/0.1 Python/2.7
Content-Length: 0
Content-Type: text/html; charset=utf-8

The Accepted response means the server has accepted the request, but gives no details on the result. In order to see any created resources, we would need to do a get GET on the list endpoint.

For detailed information on the format of a bulk request, see :ref:`patch-list`.

You Did It!

That's a whirlwind tour of interacting with a Tastypie API. There's additional functionality present, such as:

  • POST/PUT the other supported content-types
  • More filtering/order_by/limit/offset tricks
  • Using overridden URLconfs to support complex or non-PK lookups
  • Authentication

But this grounds you in the basics & hopefully clarifies usage/debugging better.