If the query parameter type is int, an error will be reported if an empty string is passed from the front end

@router.get('/listAll', summary="获取事项内容列表")
async def listAll(
        db: Session = Depends(deps.get_db),
        siteId: int = Depends(deps.setSiteId),
        itemId: int = Query(None, description='事项ID'),
        page: int = Query(1, description='页码'),
        size: int = Query(10, description='条数')
):

GET /listAll?itemId&page=1&size=10

output:

1 validation error for Request
query -> itemId
  value is not a valid integer (type=type_error.integer)

I expect itemid = NONE

[whiskeyriver]

@Alpha188 Looks like this was brought up in https://github.com/tiangolo/fastapi/issues/1147 previously. The gist is that Starlette keeps empty parameters like this as flag parameters (https://github.com/encode/starlette/issues/860). The code in question is https://github.com/encode/starlette/blob/master/starlette/datastructures.py#L125.

This results in the itemId being passed in as a blank string, rather than the NoneType you might expect:

In [1]: from urllib.parse import parse_qsl
In [2]: parse_qsl("itemId&page=1&size=10", keep_blank_values=True)
Out[3]: [('itemId', ''), ('page', '1'), ('size', '10')]

The quickest way I can think of to get around this would be with a Pydantic custom type (https://pydantic-docs.helpmanual.io/usage/types/#custom-data-types)

from pydantic import validators

class MyCustomInt(int):
    @classmethod
    def __get_validators__(cls):
        yield cls.validate

    @classmethod
    def __modify_schema__(cls, field_schema):
        field_schema.update(type="int")

    @classmethod
    def validate(cls, v):
        if v is None or v == "":
            return None
        return validators.int_validator(v)

    def __repr__(self):
        return f"MyCustomInt({super().__repr__()})"


@router.get("/listAll")
async def listAll(
    itemId: Optional[MyCustomInt] = Query(None, description="事项ID"),
    page: int = Query(1, description="页码"),
    size: int = Query(10, description="条数"),
):
    return {"itemId": itemId, "page": page, "size": size}

[Alpha188]

@dmitrijkir In some cases, it is unavoidable that the query parameters of the URL will be empty. In order to solve this problem, I can only control it on the front end. The following is the code to automatically filter the null value when sending a request using jquery

$.ajaxPrefilter(function (options, originalOptions, jqXHR) {
  if (options.type && options.type.toLowerCase() == 'get') {
    var url = '';

    for (const propName of Object.keys(originalOptions.data)) {
      const value = originalOptions.data[propName];
      var part = encodeURIComponent(propName) + "=";

      if (value != null && typeof value != "undefined") {
        if (typeof value === 'object') {
          for (const key of Object.keys(value)) {
            let params = propName + '[' + key + ']';
            var subPart = encodeURIComponent(params) + "=";
            url += subPart + encodeURIComponent(value[key]) + "&";
          }
        } else {
          url += part + encodeURIComponent(value) + "&";
        }
      }
    }

    url = url.slice(0, -1);
    options.data = url;
  }
});

I have not seen this situation in other technical frameworks, such as springMVC, they can help me deal with it intelligently