django: control json serialization

Posted by abolotnov on Stack Overflow See other posts from Stack Overflow or by abolotnov
Published on 2011-02-26T21:13:38Z Indexed on 2011/02/26 23:25 UTC
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Is there a way to control json serialization in django? Simple code below will return serialized object in json:

co = Collection.objects.all()
c = serializers.serialize('json',co)

The json will look similar to this:

[
    {
        "pk": 1,
        "model": "picviewer.collection",
        "fields": {
            "urlName": "architecture",
            "name": "\u0413\u043e\u0440\u043e\u0434 \u0438 \u0430\u0440\u0445\u0438\u0442\u0435\u043a\u0442\u0443\u0440\u0430",
            "sortOrder": 0
        }
    },
    {
        "pk": 2,
        "model": "picviewer.collection",
        "fields": {
            "urlName": "nature",
            "name": "\u041f\u0440\u0438\u0440\u043e\u0434\u0430",
            "sortOrder": 1
        }
    },
    {
        "pk": 3,
        "model": "picviewer.collection",
        "fields": {
            "urlName": "objects",
            "name": "\u041e\u0431\u044a\u0435\u043a\u0442\u044b \u0438 \u043d\u0430\u0442\u044e\u0440\u043c\u043e\u0440\u0442",
            "sortOrder": 2
        }
    }
]

You can see it's serializing it in a way that you are able to re-create the whole model, shall you want to do this at some point - fair enough, but not very handy for simple JS ajax in my case: I want bring the traffic to minimum and make the whole thing little clearer.

What I did is I created a view that passes the object to a .json template and the template will do something like this to generate "nicer" json output:

[
{% if collections %}
    {% for c in collections %}
{"id": {{c.id}},"sortOrder": {{c.sortOrder}},"name": "{{c.name}}","urlName": "{{c.urlName}}"}{% if not forloop.last %},{% endif %}
    {% endfor %}
{% endif %}
]

This does work and the output is much (?) nicer:

[
    {
        "id": 1,
        "sortOrder": 0,
        "name": "????? ? ???????????",
        "urlName": "architecture"
    },
    {
        "id": 2,
        "sortOrder": 1,
        "name": "???????",
        "urlName": "nature"
    },
    {
        "id": 3,
        "sortOrder": 2,
        "name": "??????? ? ?????????",
        "urlName": "objects"
    } 
]

However, I'm bothered by the fast that my solution uses templates (an extra step in processing and possible performance impact) and it will take manual work to maintain shall I update the model, for example.

I'm thinking json generating should be part of the model (correct me if I'm wrong) and done with either native python-json and django implementation but can't figure how to make it strip the bits that I don't want.

One more thing - even when I restrict it to a set of fields to serialize, it will keep the id always outside the element container and instead present it as "pk" outside of it.

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