Wrong types in JSON

[KathRains]

I specified the model as:

class TestRoleSchema(db_schema.SQLAlchemyAutoSchema):
    class Meta:
        model = Role

If I have the datetime field, the result JSON will be:

created:
format: "date-time"
title: "created"
type: "string"

The question is why the type is string when the original type is Date? Are there any specifications on data types?

Also, for boolean the type is presented as an array:

is_test_data:
{  title: "is_test_data"
   type: Array(2)
   0: "boolean"
   1: "null"}