FastAPI code generator generating unhashable models when using an enum

[ChrisDAT20]

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Example Code

* In an OpenAPI schema definition file, I defined an enum type:

DraftType:
  type: string
  enum:
	- Type1
	- Type2
	- Type3

which is generated to the following Python class:

class DraftType(str, Enum):
    Type1 = "Type1"
    Type2 = "Type2"
    Type3 = "Type3"

It is used in another type:

Draft:
  type: object
  properties:
	draftType:
	  $ref: "#/components/schemas/DraftType"
	version:
	  type: integer
	  format: int64
  required:
	- draftType
	- version

The classes are then used in the FastAPI app:

@async_http_exception
async def get_draft(
    draft_request: DraftRequest = Body(None, description=""),
) -> None:
    draft: Draft = DraftLoader.get_draft(draft_request=draft_request)

class DraftRequest(BaseModel):

    draft_type: DraftType = Field(alias="draftType")

DraftRequest.update_forward_refs()

class DraftLoader:
	...
	
	@staticmethod
	@lru_cache()
	def get_draft(draft_request: DraftRequest) -> Draft:
		...
		# fetch latest draft version...
		draft: Draft = ...
		...
		return draft

However, the code raises an error when calling DraftLoader.get_draft:

E             File "<!- some file path ->", line 46, in get_draft
E               draft: Draft = DraftLoader.get_draft(draft_request=draft_request)
E           TypeError: unhashable type: 'DraftRequest'

### Description

As the code is generated by FastAPI, I do not have an idea on how to make the enum hashable. 
Is there something I can add to make the enums hashable?

### Operating System

Linux

### Operating System Details

_No response_

### FastAPI Version

0.110.2

### Pydantic Version

1.10.15

### Python Version

Python 3.9.13

### Additional Context

_No response_

[YuriiMotov]

That's because you are using lru_cache and it has the following constraint:

Since a dictionary is used to cache results, the positional and keyword arguments to the function must be hashable.

To solve this you need to implement the __hash__ and __eq__ methods for DraftRequest.

Something like this (I haven't run the code below, it can contain mistakes):

class DraftRequest(BaseModel):
    draft_type: DraftType = Field(alias="draftType")

    def __hash__(self):
        return hash(self.draft_type.value)

    def __eq__(self, other: Any):
        if not isinstance(other, DraftRequest):
            return self.draft_type == other.draft_type
        return False

[ChrisDAT20]

I understood that hash and eq functions are needed. But how can I make FastAPI to add the functions to the generated code? I would like to avoid manual code changes to make the enums hashable.

[YuriiMotov]

Oh, I see.
I think it would be more correctly to say code is generated by FastAPI code generator, not code is generated by FastAPI.
Do you use this project: https://github.com/koxudaxi/fastapi-code-generator ?

[ChrisDAT20]

yes, you are right. Its fast-code-generator installed using pip.

[YuriiMotov]

Why don't you ask this question in the repo of fast-code-generator?
I think it's closer to that project then to FastAPI itself..

[YuriiMotov]

You can try using lru_cache from methodtools (from methodtools import lru_cache) (https://github.com/youknowone/methodtools)

[ChrisDAT20]

For some reason I thought fastapi and fastapi-code-generator are maintained together. I posted the issue there as well.
Thank you for the hint!