Custom Object Marshalling

[vishalkuo]

Hi there, does graphene-sqlalchemy support overriding the automapper to allow us to map resolved ORM objects to custom db objects?

As an example, I'd like a graphsql schema of the following:

class MyCustomObject(graphene.ObjectType):
  customField = Field(String)

and my ORM object:

class MyDBObject(db.Model):
  str_field = db.Column(db.String(128))

Now if I query MyCustomObject:

{
  my_custom_objects {
    customField
  }
}

I want to be able to map the custom object fields to my db object, return my db objects, and have them mapped back to MyCustomObject.

I'm fairly new to graphql and graphene, so I apologize in advance if this is an extremely basic connection or if this isn't how graphql is meant to work.

Note: the reason I'm apprehensive of just mapping the field in the resolver is that we have to return MyDBObject.query.all() which will be expensive to serialize

[jnak]

Currently there are 2 ways.

The most simple is this:

class MyCustomObject(graphene.SQLAlchemyObjectType):
    class Meta(object):
        model = MyDBObject

  customField = Field(String)

  def resolve_custom_field(obj, ...):
      return obj.str_field

There is another way not yet documented:

class MyCustomObject(graphene.SQLAlchemyObjectType):
   ...

  customField = ORMField(model_attr='str')

I don't follow your point on MyDBObject.query.all(). This logic that selects the objects needs to be in a root level resolver in your example:

class Query(graphene.SQLAlchemyObjectType):
  my_custom_objects = List(MyCustomObject)

  def resolve_my_custom_objects(...):
      return MyDBObject.query.all()   # You would add filtering here

Hope that helps!

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