[BUG] uint64 maximum 1.844...e+19 is parsed as 384 (truncation error)

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

Large integers in the OpenAPI specification are not read in correctly.

I am generating a client from a spec that specifies the uint64 maximum 1.8446744073709552e+19, but the value is parsed as 384.

openapi-generator version

5.4.0

OpenAPI declaration file content or url

Just add the size property to petstore.yaml, so it looks like this:

[...]
        status:
          type: string
          description: pet status in the store
          deprecated: true
          enum:
            - available
            - pending
            - sold        
        size:
          description: in bytes
          maximum: 1.8446744073709552e+19
          minimum: 0
          type: integer
      xml:
        name: Pet
    ApiResponse:
      title: An uploaded response
[...]

Generation Details

openapi-generator-cli generate -i petstore.yaml -g python

Steps to reproduce

The steps above produce this code:

    validations = {
        ('size',): {
            'inclusive_maximum': 384,
            'inclusive_minimum': 0,
        },
    }

inclusive_maximum should be 1.8446744073709552e+19 instead.

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/10620 is very similar.

Suggest a fix

I don't know where it happens, but it is clearly a truncation error. For 1.844e+19, the generated code is 'inclusive_maximum': -6744073709551616,.

Start with the petstore.yaml reproduction and run openapi-generator-cli generate -i petstore.yaml -g python. Trace how the maximum value reaches the generated Python validations dictionary, comparing the expected uint64 maximum with the truncated output. Done means the generated value is preserved correctly and the regression is covered by an appropriate test.