Pydantic schemav2 creates unexpected `MyOtherModel = MyModel` - still

[gothicVI]

This is a reopening of #2487

Why is this still an issue when using --output-model-type pydantic_v2.BaseModel? How can I get v2 models without the colapse?

Version:

• OS: debian 12
• Python version: 3.13
• datamodel-code-generator version: 0.42.2

[ilovelinux]

Hi, thanks for reporting the issue! 🙂

• It may have been fixed with Fix allOf with description generating alias instead of class (Pydantic v2) #2643 released in v0.43.1, could you check that?
• If the problem still persist, could you provide us a reproducible example?

[koxudaxi]

The issue has been fixed. Thank you!!

[gothicVI]

@koxudaxi can you please reopen this?

Hi all,

sorry for the late reply. Version 0.50.0 still generates class = class which breaks type checking.
I can not provide the full source due to it being proprietary, but the swagger.yaml contains

definitions:
  account:
    properties:
      _links:
        properties:
          self:
            $ref: '#/definitions/href'
            x-ntap-introduced: '9.6'
        type: object
        x-go-name: account_inline__links
        x-ntap-introduced: '9.6'
        x-ntap-readOnly: true
      applications:
        items:
          $ref: '#/definitions/account_application'
        type: array
        x-go-name: account_inline_applications
        x-ntap-introduced: '9.6'
        x-omitempty: true
      comment:
        description: Optional comment for the user account.
        type: string
        x-ntap-introduced: '9.6'
        x-nullable: true
      locked:
        default: false
        description: Locked status of the account.
        type: boolean
        x-ntap-introduced: '9.6'
        x-nullable: true
      name:
        description: User or group account name
        example: joe.smith
        maxLength: 64
        minLength: 3
        type: string
        x-ntap-introduced: '9.6'
        x-ntap-readCreate: true
        x-nullable: true
      owner:
        description: Owner name and UUID that uniquely identifies the user account.
        properties:
          _links:
            properties:
              self:
                $ref: '#/definitions/href'
                x-ntap-introduced: '9.6'
            type: object
            x-go-name: account_inline_owner_inline__links
            x-ntap-introduced: '9.6'
            x-ntap-readOnly: true
          name:
            description: 'The name of the SVM. This field cannot be specified in a
              PATCH method.

'
            example: svm1
            type: string
            x-ntap-introduced: '9.6'
            x-nullable: true
          uuid:
            description: 'The unique identifier of the SVM. This field cannot be specified
              in a PATCH method.

'
            example: 02c9e252-41be-11e9-81d5-00a0986138f7
            type: string
            x-ntap-introduced: '9.6'
            x-nullable: true
        type: object
        x-go-name: account_inline_owner
        x-ntap-introduced: '9.6'
        x-ntap-readCreate: true

And running

datamodel-codegen \
    --input /tmp/swagger.yaml \
    --input-file-type jsonschema \
    --output ./src/netapp_rest/_netapp_model.py \
    --output-model-type pydantic_v2.BaseModel \
    --field-constraints \
    --set-default-enum-member \
    --use-non-positive-negative-number-constrained-types \
    --use-standard-collections \
    --use-union-operator \
    --use-unique-items-as-set \
    --snake-case-field \
    --enable-version-header \
    --reuse-model \
    --target-python-version 3.13 \
    --use-title-as-name \
    --use-double-quotes

generates

class FieldLinks(BaseModel):
    self: Self | None = None


FieldLinks1 = FieldLinks


class Owner(BaseModel):
    field_links: FieldLinks1 | None = Field(default=None, alias="_links")
    name: str | None = Field(
        default=None, description="The name of the SVM. This field cannot be specified in a PATCH method.\n", examples=["svm1"]
    )
    uuid: str | None = Field(
        default=None,
        description="The unique identifier of the SVM. This field cannot be specified in a PATCH method.\n",
        examples=["02c9e252-41be-11e9-81d5-00a0986138f7"],
    )

while running

datamodel-codegen \
    --custom-template-dir custom_templates \
    --input /tmp/swagger.yaml \
    --input-file-type jsonschema \
    --output ./src/netapp_rest/_netapp_model.py \
    --output-model-type pydantic_v2.BaseModel \
    --field-constraints \
    --set-default-enum-member \
    --use-non-positive-negative-number-constrained-types \
    --use-standard-collections \
    --use-union-operator \
    --use-unique-items-as-set \
    --snake-case-field \
    --enable-version-header \
    --reuse-model \
    --target-python-version 3.13 \
    --use-title-as-name \
    --use-double-quotes

with custom_templates/pydantic_v2/BaseModel.jinja2

{% for decorator in decorators -%}
{{ decorator }}
{% endfor -%}
class {{ class_name }}({{ base_class }}):{% if comment is defined %}  # {{ comment }}{% endif %}
{%- if description %}
    """
    {{ description | indent(4) }}
    """
{%- endif %}
{%- if not fields and not description %}
    pass
{%- endif %}
{%- if config %}
{%- filter indent(4) %}
{% include 'ConfigDict.jinja2' %}
{%- endfilter %}
{%- endif %}
{%- for field in fields -%}
    {%- if not field.annotated and field.field %}
    {{ field.name }}: {{ field.type_hint }} = {{ field.field }}
    {%- else %}
    {%- if field.annotated %}
    {{ field.name }}: {{ field.annotated }}
    {%- else %}
    {{ field.name }}: {{ field.type_hint }}
    {%- endif %}
    {%- if not (field.required or (field.represented_default == 'None' and field.strip_default_none)) or field.data_type.is_optional
            %} = {{ field.represented_default }}
    {%- endif -%}
    {%- endif %}
    {%- if field.docstring %}
    """
    {{ field.docstring | indent(4) }}
    """
    {%- endif %}
{%- for method in methods -%}
    {{ method }}
{%- endfor -%}
{%- endfor -%}

generates

class FieldLinks(BaseModel):
    self: Self | None = None


class FieldLinks1(FieldLinks):
    pass


class Owner(BaseModel):
    field_links: FieldLinks1 | None = Field(default=None, alias="_links")
    name: str | None = Field(
        default=None, description="The name of the SVM. This field cannot be specified in a PATCH method.\n", examples=["svm1"]
    )
    uuid: str | None = Field(
        default=None,
        description="The unique identifier of the SVM. This field cannot be specified in a PATCH method.\n",
        examples=["02c9e252-41be-11e9-81d5-00a0986138f7"],
    )

Probably the best option would be to not generate numbered duplicates but that might be quite difficult to substitute correctly everywhere.

[koxudaxi]

@gothicVI
Sorry about that. I believe I introduced a bug in the template optimization. I've reverted the changes.

[gothicVI]

@koxudaxi thanks. any idea when this will be released? we came up with an ast based method to remove the duplicate classes. Is there an interest? Maybe it could be used to prevent the basically useless ones to be created in the first place?

[github-actions]

🎉 Released in 0.51.0

The fix/feature from PR #2853 has been included in this release. See the release notes for details.

Thank you for your contribution!