old_contents: from marshmallow import fields, Serializer
  
  
  class MunicipalitySerializer(Serializer):
      id = fields.Integer(attribute='code')
  
      class Meta:
          fields = ('id', 'name')
  
  
  class VoluntaryWorkTypeSerializer(Serializer):
      class Meta:
          fields = ('id', 'name')
  
  
  class VoluntaryWorkLinksSerializer(Serializer):
      municipality = fields.Integer()
      type = fields.Integer()
  
      class Meta:
          fields = ('municipality', 'type')
  
  
  class VoluntaryWorkSerializer(Serializer):
      links = fields.Nested(VoluntaryWorkLinksSerializer)
  
      class Meta:
          fields = (
              'id',
              'name',
              'description',
              'organizer',
              'contact_email',
              'street_address',
              'links',
              'url',
              'hashtag',
              'location',
              'time',
              'goal',
              'contact_phone',
              'organization'
          )
  
new_contents: from marshmallow import fields, Serializer
  
  
  class MunicipalitySerializer(Serializer):
      id = fields.Integer(attribute='code')
  
      class Meta:
          fields = ('id', 'name')
  
  
  class VoluntaryWorkTypeSerializer(Serializer):
      class Meta:
          fields = ('id', 'name')
  
  
  class VoluntaryWorkLinksSerializer(Serializer):
      municipality = fields.Integer()
      type = fields.Integer()
  
      class Meta:
          fields = ('municipality', 'type')
  
  
  class VoluntaryWorkSerializer(Serializer):
      links = fields.Nested(VoluntaryWorkLinksSerializer)
  
      class Meta:
          fields = (
              'id',
              'name',
              'description',
             # 'organizer',
             # 'contact_email',
              'street_address',
              'links',
              'url',
              'hashtag',
              'location',
              'time',
              'goal',
             # 'contact_phone',
              'organization'
          )
  
subject: remove unwanted