用于与 Flask-restful 的层次关系的封送 URL

Question

I have problems getting the flask-restful marshal_with function to do what I want. Basically I have 4 endpoints to access two hierarchical entities (parents and children).

class Parent(db.Model):
  name = db.Column(db.String, primary_key=True)
  children = db.relationship(Child)

class Child(db.Model):
  name = db.Column(db.String, primary_key=True)
  parent = db.Column(db.String, db.ForeignKey('parents.name'))

Parent resources:

parent_marshal_template = {
  'name': fields.String,
  'children': fields.Url('children-endpoint', attribute='name')
}

class Parents(Resource):  # /parents
  @marshal_with(parent_marshal_template)
  def get(self):
    return list_of_parents

class Parent(Resource):  # /parents/<str:name> (parent-endpoint)
  @marshal_with(parent_marshal_template)
  def get(self, name):
    return single_parent_with_name

Child resources:

child_marshal_template = {
  'name': fields.String,
  'parent': fields.Url('parent-endpoint', attribute='name')
}

class Children(Resource):  # /parents/<str:parent>/children (children-endpoint)
  @marshal_with(child_marshal_template)
  def get(self, parent):
    return list_of_children_of_parent

class Child(Resource):  # /parents/<str:parent>/children/<str:name>
  @marshal_with(child_marshal_template)
  def get(self, parent, name):
    return single_child_with_name

parent_marshal_template should return the URL to get all children of this parent for the 'children' key. child_marshal_template should return the URL to it's parent for the 'parent' key. Both throw errors that say that I forgot to specify values. How can I make it work?

Answer 1

You have to add the resource name.

app.add_resource(Parent,"/parent",endpoint='parent-endpoint')
app.add_resource(Child,"/child",endpoint='child-endpoint')

Once you add this, you can use the Field.Url function to point to the api endpoint.

parent_marshal_template = {
  'name': fields.String,
  'children': fields.Url('children-endpoint', attribute='name')
}

child_marshal_template = {
  'name': fields.String,
  'parent': fields.Url('parent-endpoint', attribute='name')
}