Describe the bug

Not sure if this should be a Feature request or a bug.

When returning a List of models, the response includes "unset" key/values whenresponse_model_exclude_unset is set toTrue.

To Reproduce

1. Create a file with:

importpydanticfromfastapiimportFastAPIapp=FastAPI()classItem(pydantic.BaseModel):foobar:str="foobar"foo:strbar:str=NoneALL_ITEMS= [Item(foo="foo0"),Item(foo="foo1"),Item(foo="foo2")]@app .get("/items",response_model=List[Item],response_model_exclude_unset=True)defget_all_items():returnALL_ITEMS@app .get("/items/{item_index}",response_model=Item,response_model_exclude_unset=True)defget_item(item_index:int):returnALL_ITEMS[item_index]

3. Open the browser and call the endpoint/items.
4. It returns a JSON with...

[  {"foobar":"foobar","foo":"foo0","bar":null  },  {"foobar":"foobar","foo":"foo1","bar":null  },  {"foobar":"foobar","foo":"foo2","bar":null  }]

5. But I expected it to return...

[  {"foo":"foo0"  },  {"foo":"foo1"  },  {"foo":"foo2"  }]

Expected behavior

I would expect/items and/items/{item_index} to return the same representation of an item.

Screenshots

Environment

• OS: Windows and MacOS
• FastAPI Version: 0.47.1
• Python version: 3.7.3

Additional context

The main thing I'm trying to achieve here is to exclude nulls when using List[MyModel]. Currently, the only workaround that I know of is to do one of the following.

1. create a new responseAllItems model and overloaddict()
2. create amiddleware that strips response nulls.
3. use an arbitrary dict (I don't want to do this)

However, given the prevalence of API's that have a/<all_items>,/<single_item> I would think that usingresponse_model_exclude_unset orexclude_none is the more intuitive way to achieve this.