根据数据覆盖字段模式-棉花糖 [英] Override field schema based on data - Marshmallow

问题描述

我刚开始使用棉花糖，所以如果有解决问题的更优雅的方法，请告诉我.字段会根据用户类型(学生/工作人员)而有所不同

I'm just getting started with marshmallow so if there's a more elegant way to solve the issue please let me know. Fields will be varied based on the user type (student/staff)

{
   "type": "student",   
   "name": "Student 1",
   "class": "V Std",
   "section": "A Class"
}

如果输入 Staff ，我们需要验证 designation 和 experience 跳过 class 和 section

if type Staff we need to validate designation and experience skip class and section

{
   "type": "staff",   
   "name": "Staff 1",
   "designation": "Professor",
   "experience": "2 Year"
}

我有以下简单的模型和架​​构.

I have the following simple model and schema.

class AddUser(Resource):
   def post(self):
      content = request.get_json(silent=True)
      try:
         data = UserSchema().load(content)       
         print(data)

      except ValidationError as err:
         return err.messages, 400

class UserSchema(Schema):
   type = fields.Str(required=True,validate=OneOf(['student', 'staff'], error='Invalid User Type'), error_messages={'required': 'User type required'})
   name = fields.Str(required=True)
   class = fields.Str()
   section = fields.Str()
   designation = fields.Str()
   experience = fields.Str()

   @post_load
   # @pre_load
   # @validates_schema
   def unwrap_envelope(self, data):   
     student = {
       class: fields.Str(required=True),
       section: fields.Str(required=True)
     }

      staff = {
       designation: fields.Str(required=True),
       experience: fields.Str(required=True)
     }

     # Fields are getting updated but it is **not raising the error**

     if data['type'] == 'student':
       self.declared_fields.update(student)
     elseif data['type'] == 'staff':
       self.declared_fields.update(staff)

     return data

推荐答案

我认为您正在寻找的是多态性.

I think what you're looking for is polymorphism.

要实现这一目标并非易事，而且棉花糖还没有一种简便的方法来实现.您可以检查 marshmallow-oneofschema 和

It's not straightforward to achieve and marshmallow does not come with an easy way to do it. You can check marshmallow-oneofschema and marshmallow-polyfield. Those two third-party libraries are meant for that. They both have their pros and cons, so none of them was included in marshmallow core.

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