CODEWITHSUNDEEP
pythonsqlalchemymarshmallow
rakesh mallesh
rakesh mallesh

Reputation: 178

Filter Nested field in Flask Marshmallow

I want to filter the nested field with is_active column as True in Marshmallow 3 Consider following scenario I have 3 tables

users (id, name)
organizations (id, name)
organization_user(id, organization_id, user_id, is_active)

Now I'm trying to print all the organization with its members who are active. (There are some active and inactive members)

I have following schema 

class OrganizationSchema(ma.ModelSchema):
    members_list = fields.Nested(OrgnizationUserSchema, many=True, exclude=('checklist', ))

class OrgnizationUserSchema(ma.ModelSchema):
    user_list = fields.Nested(UserSchema)

Now in my action following is the code

organization_schema = OrganizationSchema(many=True)
#Query for list of organization
organization_list = Organization.query.all()
organization_schema.dump(organization_list)

Following is Output

[
    {
    'id': 1,
    'name': 'abc',
    'members_list': [
        {'id':1, 'organization_id': 1, 'user_id':1, 'is_active':True},
        {'id':1, 'organization_id': 1, 'user_id':2, 'is_active':False}
        ]
    }
]

I want output with member who has 'is_active':True as follows

[
    {
    'id': 1,
    'name': 'abc',
    'members_list': [
        {'id':1, 'organization_id': 1, 'user_id':1, 'is_active':True}
        ]
    }
]

Marshmallow provides a decorator @post_dump. Problem here is Query brings all data and then we filter it with decorator @post_dump. But the flow should be like, while querying there should be some way to filter the data and not post query filtering.

Upvotes: 8

Views: 2919

Answers (2)

Gabor
Gabor

Reputation: 382

I know you haven't mentioned SQLAlchemy, but I have come across the same problem and I have ended up with a solution that used primaryjoin (may help somebody)

SQLAlchemy DOC

My issue was related to soft delete, so instead of modifying Marshmallow I have defined a primaryjoin for the SqlalAlchemy model, like below. This allowed me to return the products as a sublist for a company but only the non-deleted ones.

[code just illustration]

class Company():
    __tablename__ = "companies"

    products = db.relationship(
        "Product",
        backref="company",
        primaryjoin="and_(Company.id==Product.company_id, "
                    "Product.deleted == True)"
    )

Upvotes: 0

V. Chikunov
V. Chikunov

Reputation: 56

I went the other way. I have cloths, designs and remainders. For each fabric I need to get all the designs, and for each design will get the remainders for the specified city.

class ClothSchema(Schema):
    id = fields.Integer(dump_only=True)
    name = fields.String(validate=not_blank)
    type = fields.Nested(ClothTypeSchema)
    designs = fields.Nested(DesignSchema, many=True)

class DesignSchema(Schema):
    id = fields.Integer(dump_only=True)
    name = fields.String(validate=not_blank)
    remainders = fields.Nested(RemainderSchema, many=True)

class RemainderSchema(Schema):
    id = fields.Integer(dump_only=True)
    value = fields.String()
    city = fields.String()

I get the data I need in the controller so that they are not requested on the go.

    db.session.query(Cloth)
    .join(Cloth.designs)
    .join(Design.remainders)
    .filter(Remainder.city == city)
    .options(contains_eager("designs").contains_eager("remainders"))

As a result, I get all the cloths and all the designs for which the remainders are given. If no design remainders are indicated, it will not be displayed.

{
  "attributes": {
    "designs": {
      "data": [
        {
          "attributes": {
            "name": "Amely 10 ", 
            "remainders": {
              "data": [
                {
                  "attributes": {
                    "city": "CityEnum.MOSCOW", 
                    "value": "333"
                  }, 
                  "id": 9318, 
                  "type": "remainder"
                }
              ]
            }
          }, 
          "id": 365, 
          "type": "design"
        } 
      ], 
      "links": {
        "self": "/designs"
      }
    }, 
    "name": "Amely", 
    "rapport": null, 
    "type": {} 
  }, 
  "id": 22, 
  "type": "cloth"
}

Upvotes: 3

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