Fix none related issues

[AntoineD]

trafficstars

For a schema with a property that can be null and has a null default value, the pydantic model is not correctly generated. For instance:

{
  "properties": {
    "name": {
      "type": ["null", "string"],
      "default": "null"
    },
  },
  "type": "object"
}

is converted to

class Model(BaseModel):
    name: Optional[Optional[str]] = 'null'

instead of

class Model(BaseModel):
    name: Optional[str] = None

This PR addresses the default value conversion and the duplicated Optional.

[codecov[bot]]

Codecov Report

Base: 100.00% // Head: 99.92% // Decreases project coverage by -0.07% :warning:

Coverage data is based on head (2bcc5b1) compared to base (e9b6edf). Patch coverage: 99.90% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff             @@
##            master     #840      +/-   ##
===========================================
- Coverage   100.00%   99.92%   -0.08%     
===========================================
  Files           11       21      +10     
  Lines         1020     2603    +1583     
  Branches       201      616     +415     
===========================================
+ Hits          1020     2601    +1581     
- Misses           0        1       +1     
- Partials         0        1       +1     

Flag	Coverage Δ
unittests	99.84% <99.80%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
datamodel_code_generator/model/__init__.py	100.00% <ø> (ø)
datamodel_code_generator/types.py	99.01% <98.78%> (ø)
datamodel_code_generator/__init__.py	100.00% <100.00%> (ø)
datamodel_code_generator/__main__.py	100.00% <100.00%> (ø)
datamodel_code_generator/format.py	100.00% <100.00%> (ø)
datamodel_code_generator/http.py	100.00% <100.00%> (ø)
datamodel_code_generator/imports.py	100.00% <100.00%> (ø)
datamodel_code_generator/model/base.py	100.00% <100.00%> (ø)
datamodel_code_generator/model/enum.py	100.00% <100.00%> (ø)
...atamodel_code_generator/model/pydantic/__init__.py	100.00% <100.00%> (ø)
... and 18 more

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[AntoineD]

Hi @koxudaxi, it looks like you've rebased this PR, the failing CI jobs are due to codecov. Do you need me to do something?

[koxudaxi]

@AntoineD Thank you for creating the PR. I re-run the failed CI.

Btw, How do we set "null" string value as default? Also, Can we use "default": null for default?

[AntoineD]

@koxudaxi

Btw, How do we set "null" string value as default?

I do not know.

Also, Can we use "default": null for default?

I would say yes in a json file.

[koxudaxi]

@AntoineD

Btw, How do we set "null" string value as default? I do not know.

We should not break current behavior. This is not a bug.

[koxudaxi]

no update