How do I return a JSON array with Bottle?

Question

I'm writing an API using Bottle, which so far has been fantastic. However, I've run up against a small hurdle when trying to return a JSON array. Here's my test app code:

from bottle import route, run

@route('/single')
def returnsingle():
    return { "id": 1, "name": "Test Item 1" }

@route('/containsarray')
def returncontainsarray():
    return { "items": [{ "id": 1, "name": "Test Item 1" }, { "id": 2, "name": "Test Item 2" }] }

@route('/array')
def returnarray():
    return [{ "id": 1, "name": "Test Item 1" }, { "id": 2, "name": "Test Item 2" }]

run(host='localhost', port=8080, debug=True, reloader=True)

When I run this and request each route, I get the JSON responses I'd expect from the first two routes:

/single

{ id: 1, name: "Test Item 1" }

/containsarray

{ "items": [ { "id": 1, "name": "Test Item 1" }, { "id": 2, "name": "Test Item 2" } ] }

So, I had expected returning a list of dictionaries to create the following JSON response:

[ { "id": 1, "name": "Test Object 1" }, { "id": 2, "name": "Test Object 2" } ]

But requesting the /array route just results in an error. What am I doing wrong, and how can I return a JSON array in this manner?

Solution 1

Bottle's JSON plugin expects only dicts to be returned - not arrays. There are vulnerabilities associated with returning JSON arrays - see for example this post about JSON hijacking.

If you really need to do this, it can be done, e.g.

@route('/array')
def returnarray():
    from bottle import response
    from json import dumps
    rv = [{ "id": 1, "name": "Test Item 1" }, { "id": 2, "name": "Test Item 2" }]
    response.content_type = 'application/json'
    return dumps(rv)

Solution 2

According to Bottle's 0.12 documentation:

As mentioned above, Python dictionaries (or subclasses thereof) are automatically transformed into JSON strings and returned to the browser with the Content-Type header set to application/json. This makes it easy to implement json-based APIs. Data formats other than json are supported too. See the tutorial-output-filter to learn more.

Which means you don't need to import json nor setting the content_type attribute of the response.

Thus, the code gets hugely reduced:

@route('/array')
def returnarray():
    rv = [{ "id": 1, "name": "Test Item 1" }, { "id": 2, "name": "Test Item 2" }]
    return dict(data=rv)

And the JSON document returned by the Web server would look like:

{"data": [{"id": 1, "name": "Test Item 1"}, {"id": 2, "name": "Test Item 2"}]}

Comments

[Mark Bell]

Thanks, that's an interesting article. Good to know I can still do this if I'm careful, though!

[crunkchitis]

Thanks a million for this one.

[Dacav]

Javascript, why on the earth would you do that? Thanks man, here your +1

[Tejas Tank]

Most correct way of code bottle json response. thanks.