Working with Dynamic Keys in JSONObject in Django

You're facing a limitation with Django's JSONObject function, which currently doesn't support dynamic keys based on expressions. This is indeed a known limitation in Django 5.1.

Current Functionality

The JSONObject function in Django allows you to create JSON objects from key-value pairs, but the keys must be static strings. For example:

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from django.db.models import F
from django.db.models.functions import JSONObject, Lower

author = Author.objects.annotate(
    json_object=JSONObject(
        name=Lower("name"),
        alias="alias",
        age=F("age") * 2,
    )
).get()

This produces a JSON object with static keys like {"name": "margaret smith", "alias": "msmith", "age": 50}.

The Limitation

You cannot currently use expressions for the keys themselves, which makes it difficult to generate JSON objects with dynamic keys like "user.id" for Elasticsearch DSL.

Workarounds

Since this feature isn't currently available in Django, you might consider these workarounds:

1. Post-processing in Python: Query the data you need and construct the JSON object with dynamic keys in Python code after retrieving the data from the database.

2. Raw SQL: Use raw SQL queries with your database's JSON functions if they support dynamic keys.

3. Custom Database Function: Create a custom database function that wraps the native JSON object creation function of your database, if it supports dynamic keys.

4. Temporary Static Structure: Create a JSON structure with static keys that you can later transform into your desired structure with dynamic keys.

Querying JSON Data

While you can't create JSON objects with dynamic keys directly, Django does provide robust support for querying JSON data with nested keys:

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# Querying based on a key in a JSON field
Dog.objects.filter(data__breed="collie")

# Querying nested structures
Dog.objects.filter(data__owner__name="Bob")

# Querying array elements
Dog.objects.filter(data__owner__other_pets__0__name="Fishy")

# Checking if a key exists
Dog.objects.filter(data__has_key="owner")

Future Developments

The pull request you mentioned (PR #19101) aims to add support for dynamic keys in JSONObject. If this gets merged, it would address your use case. Until then, you'll need to use one of the workarounds mentioned above.

If this feature is important to you, consider contributing to the discussion on the pull request or ticket to express your use case and why this feature would be valuable.