I have a marshmallow schema validation like this:
class MyFilterSchema(Schema): ids = fields.List(fields.Str(validate=non_empty), required=True)
Then in my endpoint I call the schema validation: MyFilterSchema().load(flask.request.args)
Now I try to call the HTTP GET endpoint which is using this validation. But I get 'ids': ['Not a valid list.']
I tried different ways:
/myendpoint?ids=1,2,3 /myendpoint?ids=1&ids=2 /myendpoint?ids=[1,2]
but no luck. How must the endpoint be called that marshmallow recognizes my GET parameter as list?
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Answer
One way is to use a custom implementation of a validation field instead of the integrated list field.
class DelimitedListField(fields.List): def _deserialize(self, value, attr, data, **kwargs): try: return value.split(",") except AttributeError: raise exceptions.ValidationError( f"{attr} is not a delimited list it has a non string value {value}." )
This can be used in the schema as follow:
class MyFilterSchema(Schema): ids = DelimitedListField(fields.Str(validate=non_empty), required=True)
and would accept calls in the format:
/myendpoint?ids=1,2,3