ValueError: dictionary update sequence element #0 has length 3; 2 is required

[v-v-vishnevskiy]

This happens when I try to send something like this in body:

[
  {"name": "John"},
  {"name": "Max"}
]

with appropriate request schema.

The error in this line https://github.com/maximdanilchenko/aiohttp-apispec/blame/master/aiohttp_apispec/middlewares.py#L37
kwargs is dictionary and can't update with list or tuple.

[v-v-vishnevskiy]

And in which cases may have several request schemas?

[maximdanilchenko]

In my opinion it is more correct and clear to have a name for each value in request body.
Like this:

class Person(Schema):
    name = fields.String()

class ManyPersons(Schema):
    persons = fields.Nested(Person, many=True)

Now you can use ManyPersons schema in @request_schema decorator and body of your request will be like:

{
    "persons": [
      {"name": "John"},
      {"name": "Max"}
    ]
}

I think that it is more understandable approach for API users.

I will think about your case as well. I will try to make a patch to fix it.

[georg-wolflein]

This error also occurs when deserialising to objects.

For example:

class SomeObject(typing.NamedTuple):
    x: int
    y: int


class SomeObjectSchema(Schema):
    x = fields.Int()
    y = fields.Int()

    @post_load
    def make_object(self, data: dict):
        return SomeObject(**data)

@request_schema(SomeObjectSchema())
async def index(request):
     # ...

[georg-wolflein]

PR #57 fixes this for me, but I'm not sure if that solves @v-v-vishnevskiy's exact problem too.