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?
Answers:
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)
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"}]}
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?
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)
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"}]}