import nested json data

[matthewhegarty]

Discussed in https://github.com/django-import-export/django-import-export/discussions/1506

^{Originally posted by biscotty666 October 24, 2022}
Hi,
I need to import some data from json. The data contains nested objects and I’m unclear how to reference through to that data when writing the resource. I only see documentation about how to access fields at the “root” level of the data structure, not the nested levels. There is a bunch of info on exporting nested structures to json but I haven’t found anything on importing.

[{
    "somekeys": somevalues,
    "roster": [
      {
        "id": "P2021130273",
        "name": "Benja",
        "level": 85,
      },
      { more records },
    ]
}]

My goal is to map to the ids in the “roster” list. Where could I look for this information?

Thanks

[matthewhegarty]

@biscotty666 One way you could maybe do it is to override before_import() and add a new column(s) to the dataset which flattens the data. This modifies the dataset in places to add columns you can work with.

Here is an example using BookResource from the example application. You can play around with this idea to see if it works for you.

class BookResource(ModelResource):

    class Meta:
        model = Book

    def before_import(self, dataset, using_transactions, dry_run, **kwargs):
        import tablib
        ids = [i["roster"][0]["id"] for i in dataset.dict]
        dataset.append_col(ids, header="id")
        print(dataset)

[biscotty666]

Thanks. I will try this out tonight. Quick question though I know it's out of scope: I'm thinking of making this a separate app and plugging it in to my main project. Would that make sense? (I'm learning django and wonder if structuring the project this way is appropriate.)

[matthewhegarty]

You normally wouldn't make a dependency a separate app. I guess if you apply a lot of customisations to it (i.e. creating your own resources, and overriding methods) then you might want it to be a separate app, but in most cases it would be overkill to create a separate app.

[matthewhegarty]

Closing - discussion continues in #445