[Python-experimental] JSON schema 'null' type should be modeled as 'none_type'

[sebastien-rosset]

It looks like recently something changed because the JSON schema null type is now causing problems. I'm not sure what specific commit caused this problem. The getTypeString function in PythonClientExperimentalCodegen.java is incorrectly returning null when the input Schema is the Null type.

For example, with the following schema, the generated python-experimental code has syntax errors.

Foo:
  oneOf:
    - type: 'null'
    - '#/components/schemas/Bar'

Without this PR, the following import is incorrectly generated:

try:
    from openapi_client.models import null
except ImportError:
    null = sys.modules[
        'openapi_client.models.null']

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[sebastien-rosset]

@spacether , I'm not sure if I should handle the OAS null type in the getTypeString function (as proposed in this PR), or by adding the "null" type in the typeMapping field.

[spacether]

I think that we need to add the type mapping but I have not used that before. For Python-experimental we should point it to our already defined none_type.

[sebastien-rosset]

I think that we need to add the type mapping but I have not used that before. For Python-experimental we should point it to our already defined none_type.

ok, sure, let me try with typeMappings.

[spacether]

Please add a python test showing deserializing a None working correctly.

[sebastien-rosset]

Please add a python test showing deserializing a None working correctly.

Added unit test

[spacether]

These python-experimental updates look good. Thank you for this PR.

[spacether]

@sebastien-rosset we need the CI tests to pass before we can merge this.
Travis says:

E     File "/home/travis/build/OpenAPITools/openapi-generator/samples/client/petstore/python-experimental/petstore_api/model_utils.py", line 137
E       oneof_anyof_classes = cls._composed_schemas.get('oneOf', ()) +
E                                                                    ^
E   SyntaxError: invalid syntax

It might need parens around that statement because it is multiline, like:

oneof_anyof_classes = (first_part +
  second_part)

Can you fix it?

[spacether]

@sebastien-rosset to fix this next CI-error you need to update this line:
https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/python/python-experimental/model_templates/model_simple.mustache#L14
to:

_composed_schemas = {}

or change the oneof_anyof_classes assignment in __new__ to only assign a value if bool(cls._composed_schemas) == True which is equivalent to:

oneof_anyof_classes = ()
if cls._composed_schemas:
  oneof_anyof_classes = (cls._composed_schemas.get('oneOf', ()) +
                                cls._composed_schemas.get('anyOf', ()))

[sebastien-rosset]

@sebastien-rosset to fix this next CI-error you need to update this line:
https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/python/python-experimental/model_templates/model_simple.mustache#L14
to:

_composed_schemas = {}

or change the oneof_anyof_classes assignment in __new__ to only assign a value if bool(cls._composed_schemas) == True which is equivalent to:

oneof_anyof_classes = ()
if cls._composed_schemas:
  oneof_anyof_classes = (cls._composed_schemas.get('oneOf', ()) +
                                cls._composed_schemas.get('anyOf', ()))

I have some something like that here: https://github.com/OpenAPITools/openapi-generator/pull/5809/files#diff-cc72ac40056827e3a103f9b4f56059cfR70

I mentioned #5809 should be merged before this PR.

[spacether]

Thanks for this PR. The python-experimental updates look good to me.
Waiting for tests to pass.