Add support for booleans and floats in OpenAPI Schema const (#1086)

We encountered the problem that the Pydantic Schemas for the OpenAPI
spec, do not support the `const` keyword if it is of type `boolean`.

## Why do I think it should be supported?

The [OpenAPI
Specification](https://swagger.io/docs/specification/data-models/keywords/)
explicitly marks the `const` keyword as unsupported. Nevertheless it
should not result in exceptions if the keyword is present.

I furthermore did not find any evidence in [JSON
Schema](https://json-schema.org/understanding-json-schema/reference/const)
that would limit the types valid for the `const` keyword to be `string`
or `integer` only.

Thus I suggest allowing `boolean` as well as `floats` as constant
values.


## Example

The following is minimal example in FastAPI that would produce such a
schema:

```python
from typing import Literal

import uvicorn
from fastapi import FastAPI
from pydantic import BaseModel, Field


class ResponseWithConstantBool(BaseModel):

    message: str = Field(...)
    is_welcome: Literal[True] = Field(True)


app = FastAPI()


@app.get("/", response_model=ResponseWithConstantBool)
async def root():
    return {"message": "Hello World"}


if __name__ == "__main__":
    uvicorn.run(app)
```

### Generated OpenAPI Specification

```json
{
  "openapi": "3.1.0",
  "info": {
    "title": "FastAPI",
    "version": "0.1.0"
  },
  "paths": {
    "/": {
      "get": {
        "summary": "Root",
        "operationId": "root__get",
        "responses": {
          "200": {
            "description": "Successful Response",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/ResponseWithConstantBool"
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "ResponseWithConstantBool": {
        "properties": {
          "message": {
            "type": "string",
            "title": "Message"
          },
          "is_welcome": {
            "type": "boolean",
            "enum": [true],
            "const": true,
            "title": "Is Welcome",
            "default": true
          }
        },
        "type": "object",
        "required": [
          "message"
        ],
        "title": "ResponseWithConstantBool"
      }
    }
  }
}
```

---------

Co-authored-by: Felix Fanghaenel <[email protected]>
Co-authored-by: Dylan Anthony <[email protected]>
Co-authored-by: Dylan Anthony <[email protected]>

Author: 3 people

.changeset/support_const_booleans_and_floats.md

@@ -0,0 +1,7 @@
+---
+default: patch
+---
+
+# Support `const` booleans and floats
+
+Fixed in PR #1086. Thanks @flxdot!

openapi_python_client/parser/properties/const.py

@@ -27,7 +27,7 @@ class ConstProperty(PropertyProtocol):
     def build(
         cls,
         *,
-        const: str | int,
+        const: str | int | float | bool,
         default: Any,
         name: str,
         python_name: PythonIdentifier,

openapi_python_client/schema/openapi_schema_pydantic/schema.py

@@ -1,6 +1,6 @@
 from typing import Any, Dict, List, Optional, Union
 
-from pydantic import BaseModel, ConfigDict, Field, StrictInt, StrictStr, model_validator
+from pydantic import BaseModel, ConfigDict, Field, StrictBool, StrictFloat, StrictInt, StrictStr, model_validator
 
 from ..data_type import DataType
 from .discriminator import Discriminator
@@ -36,7 +36,7 @@ class Schema(BaseModel):
     minProperties: Optional[int] = Field(default=None, ge=0)
     required: Optional[List[str]] = Field(default=None, min_length=1)
     enum: Union[None, List[Any]] = Field(default=None, min_length=1)
-    const: Union[None, StrictStr, StrictInt] = None
+    const: Union[None, StrictStr, StrictInt, StrictFloat, StrictBool] = None
     type: Union[DataType, List[DataType], None] = Field(default=None)
     allOf: List[Union[Reference, "Schema"]] = Field(default_factory=list)
     oneOf: List[Union[Reference, "Schema"]] = Field(default_factory=list)

tests/test_schema/test_schema.py

@@ -12,6 +12,11 @@ def test_nullable_with_allof():
     assert schema.allOf == []
 
 
+def test_constant_bool():
+    schema = Schema.model_validate_json('{"type":"boolean", "enum":[true], "const":true, "default":true}')
+    assert schema.const is True
+
+
 def test_nullable_with_type_list():
     schema = Schema.model_validate_json('{"type": ["string", "number"], "nullable": true}')
     assert schema.type == [DataType.STRING, DataType.NUMBER, DataType.NULL]