[BUG] python pydantic - generates invalid files

[black-snow]

Describe the bug.

asyncapi generate models python backend/docs/asyncapi.yml --pyDantic -o backend/src/generated/models --packageName=src.generated.models

produces invalid files like:

class AnonymousSchema1(BaseModel): 
  id: str = Field()
  source: str = Field(default=''xxx'', frozen=True)

I also don't see why some files/classes are created with a reasonable name and others are AnonymousSchemaN. Adding a title or name doesn't seem to make the difference.

Expected behavior

The value of default param should be a proper string - so " or ''' enclosed.

Screenshots

How to Reproduce

The source for this should be:

channels:
  A:
    # ...
    messages:
      M:
        description: xyz
        contentType: application/json
        payload:
          allOf:
            - allOf: # ...
            - description: xyz
              type: object
              properties:
                type:
                  type: string
                  # this here
                  const: xxx
                source:
                  type: string
                  # this as well
                  const: xxx
                subject:
                  type: string
                  const: xyz
              required:
                - type
                - source
                - subject

🖥️ Device Information [optional]

• Operating System (OS): macOS

👀 Have you checked for similar open issues?

• I checked and didn't find similar issue

🏢 Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines

Are you willing to work on this issue ?

No, someone else can work on it

[github-actions]

Welcome to AsyncAPI. Thanks a lot for reporting your first issue. Please check out our contributors guide and the instructions about a basic recommended setup useful for opening a pull request.
Keep in mind there are also other channels you can use to interact with AsyncAPI community. For more details check out this issue.

[dosubot]

This bug is caused by invalid string quoting in the generated Python code, specifically in the default values for Pydantic fields. The AsyncAPI generator delegates Python model generation to Modelina's PythonGenerator, which is responsible for formatting these default values. The Models component in the generator does not handle string quoting itself—it simply passes the data to Modelina and writes out whatever Modelina generates. This means the root cause is likely in Modelina's Python code generation logic, not in the AsyncAPI generator templates or configuration. There are currently no workarounds or configuration options available to fix or avoid this issue in the generator or its documentation, and no relevant support threads discuss this bug. The fix will need to happen in Modelina's PythonGenerator logic that handles string default values.
Reference

To reply, just mention @dosu.

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[black-snow]

Probably related to

modelina/src/generators/python/presets/Pydantic.ts

Line 10 in 98e9036

return `'${constValue}'`;

- I don't quite understand how the generator works but looking at the rest of the code this should perhaps be triple single quotes as well.

[SHUBHANSHU602]

hey ,since you are not interested in this I would love to take this after approval.

[Adi-204]

@black-snow actually you are using cli and we have syntax asyncapi generate models but in generator we don't have anything regarding models generation so this should be issue of https://github.com/asyncapi/modelina

cc @derberg

[black-snow]

@Adi-204 should I create a dupe in modelina then?

(Quick user perspective: It's kinda hard to open issues in the correct repo - wdyt about having just one place for all asyncapi-related issues instead?)