DataclassJSONField implementation

[ghost]

as discussed in #75

WIP WIP WIP

Example

@dataclass
class MyDataclass(JsonSchemaMixin):
    id: int
    whatever: str


class MyModel(TimestampedModel):
    single = DataclassJSONField(MyDataclass, null=True)
    many = DataclassJSONField(MyDataclass, many=True, blank=True, default=list)

In [1]: m = MyModel.objects.first()

In [2]: m.single
Out[2]: MyDataclass(id=123, whatever='123')

In [3]: m.many
Out[3]: [MyDataclass(id=123, whatever='123'), MyDataclass(id=456, whatever='456')]

In [4]: m.single.whatever='hello'

In [5]: m.many[0].whatever='world'

In [6]: m.many.pop()
Out[6]: MyDataclass(id=456, whatever='456')

In [7]: m.save()

In [8]: m = MyModel.objects.first()

In [9]: m.single
Out[9]: MyDataclass(id=123, whatever='hello')

In [10]: m.many
Out[10]: [MyDataclass(id=123, whatever='world')]

[ghost]

so it's overridable

[ghost]

This many convention comes from Django Rest Framework

But we can consider making this a DataclassArrayJSONField instead

[bhch]

I'm going to leave this decision up to you. I'm not familiar with the dataclasses-jsonschema library. So, whatever you think works best, we can go with that.

[ghost]

TODO

[ghost]

I don't think we should add this as a dependency to this project.

Need to research how to make this contrib module optional.

Maybe removing the contrib/__init__,py would work?

[bhch]

This is okay.

To make it an optional dependency, please modify the setup.cfg file and add this at the end:

+ 
+ [options.extras_require]
+ contrib-dataclasses = dataclasses-jsonschema

Users who wish to use this feature can install the dependencies by:

pip install "django-jsonform[contrib-dataclasses]"

[ghost]

@bhch , I'm unsure if this should become it's own package django-dataclass-field. Thoughts?

[bhch]

I'm unsure if this should become it's own package django-dataclass-field. Thoughts?

Maybe.

If the goal is to have a dataclass interface to work with json data, why can't we write a function (or a method on JSONField) to convert the json data to a dataclass?

def json_to_dataclass(json_data, dataclass):
    return dataclass_instance

We can also accept a dataclass for the schema argument. And then do the conversions internally.

---

Anyway, I've reviewed the changes and left some comments.

[bhch]

This is okay.

To make it an optional dependency, please modify the setup.cfg file and add this at the end:

+ 
+ [options.extras_require]
+ contrib-dataclasses = dataclasses-jsonschema

Users who wish to use this feature can install the dependencies by:

pip install "django-jsonform[contrib-dataclasses]"

[bhch]

The code example in your comment above gives me KeyError: 'required'. Perhaps use this instead:

Suggested change

	del schema["required"]
	schema.pop("required", None)

[bhch]

Line 21 also results in a KeyError: 'item'.

[ghost]

Hmm.. This shouldn't be happening.

What Python and dataclasses-jsonschema versions are you using?

[bhch]

Python: 3.8

dataclasses-jsonschema: 2.16.0

[ghost]

I'm using dataclasses-jsonschema[fast-validation]==2.16.0 and Python 3.10

Will have to try 3.8 later (or make a separate package and drop support for older versions)

I noticed you're supporting a lot of older Django versions too. I only tested with Django==4.1.3

[bhch]

Just tested with Python 3.10 and Django 4.1.3. Everything works fine this time.

[bhch]

I'm going to leave this decision up to you. I'm not familiar with the dataclasses-jsonschema library. So, whatever you think works best, we can go with that.

[dongyuzheng]

FYI: I am @ghost. I had to delete my other account for logistics reasons.

I'm starting to lean towards making a separate package because I don't have time to investigate and support older Python/Django versions.

My next step is to fix the "required" fields, because on Admin, I can't submit empty for fields like x: int | None

[dongyuzheng]

@bhch does your library support json schema with anyOf? https://stackoverflow.com/questions/35450405/how-to-represent-sum-union-types-in-in-json-schema

Edit:

Looks like No. It fails here

[bhch]

Currently, anyOf doesn't work but it will be added (#39). I can't seem to come up with a good approach to create forms for anyOf/allOf/oneOf.

I'm starting to lean towards making a separate package because I don't have time to investigate and support older Python/Django versions.

That's understandable. I'd like to avoid breaking changes until the next major release (v3).

[dongyuzheng]

Another question @bhch , I noticed that the Django admin form sends Empty String for empty integer field, rather than null

I know this is probably because it's hard to tell the difference between null and no input and empty string.

One thing Swagger UI does is they have a tick box [] Send empty value to indicate sending a null.

Thoughts on adding this to the Form?

[bhch]

@dongyuzheng Okay, I'll add something similar to that. I've just created an issue for this: #78