Django Rest Framework add object with foreign key and depth = 1

Question

Using Django Rest Framework, I am attempting to add a model object via POST, specifying the id of an existing object to which the new object should have a foreign key. Works. If I add a depth=1 to the new object's serializer however, so that I get the foreign key target in a GET, the POST to add a new object fails with a mysql error 'IntegrityError: (1048, "Column 'reportdefinition_id' cannot be null")', even though I specify a valid foreign key id in my POST.

I can work around this by leaving the depth = 1 out and retrieving the reportdefinition separately in my client, but that's cumbersome.

(I found two related questions, but neither answers mine: Django REST - Create object with foreign key using serializers Need to show Foreign Key Object in Details by Django Rest Framework)

Models (I've not shown irrelevant fields):

class ReportDefinition(models.Model):
    name = models.CharField(max_length=254, blank=True, null=True)

class ReportRun(models.Model):
    status = models.IntegerField(default=2)
    reportdefinition = models.ForeignKey(ReportDefinition)

Serializers:

class ReportDefinitionSerializer(serializers.ModelSerializer):
    id = serializers.ReadOnlyField()
    class Meta:
        model = models.ReportDefinition
        fields = ("id","name")

class ReportRunSerializer(serializers.ModelSerializer):
    id = serializers.ReadOnlyField()
    class Meta:
        depth = 1
        model = models.ReportRun
        fields =("id","status","reportdefinition")

If I remove 'depth = 1', the POST works.

class ReportRunSerializer(serializers.ModelSerializer):
    id = serializers.ReadOnlyField()
    class Meta:
        model = models.ReportRun
        fields =("id","status","reportdefinition")

The POST contents (again, irrelevant other attributes not shown):

reportdefinition:1

One thing I noticed: without the depth = 1, the DRF browsable API shows "reportdefinition" in its default, but with depth = 1, it does not. I have to add it explicitly.

DRF browsable API content with depth = 1:

{
    "status": null,
}

(I add "reportdefinition": 1 when issuing the POST, and verify that it appears using Chrome Developer Tools)

DRF browsable API content with no 'depth = 1':

{
    "status": null,
    "reportdefinition": null
}

(I replace null with 1 when issuing the POST)

humble.jok · Accepted Answer · 2018-02-02 12:51:19Z

3

The question is quite old but as nobody responded and as I had the same issue.

In fact, the response lies in the release note of version 3.0:

If you define a depth, you now have to write your own create and update methods that will handle the modification of the nested fields.

Link to documentation.

answered Feb 2, 2018 at 12:51

humble.jok

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