Rails nested serializer not using methods to break out keys - ruby-on-rails

Question

I want to use a serializer within another serializer so I can add a key-value pair at the top level but seems like when I do, the lower level serializer isn't working anymore-
My files:
ItemsController
class ItemsController
def index
open_items = Items.
select("distinct on (open_item_id) *").
preload(:company, :project)
total = open_items.count("id")
render json: {
total: total,
items: paginate(open_items, per_page: 2), serializer: ItemsSerializer
}, status: :ok
end
end
ItemsSerializer
class ItemsSerializer < ActiveModel::Serializer
attribute :total
has_many :items, serializer: ItemSerializer
end
ItemSerializer
class ItemSerializer < ActiveModel::Serializer
attributes :id,
:project,
:company,
def company
{
name: object.company.name,
id: object.company.id
}
end
def project
{
name: object.project.name,
id: object.project.id
}
end
end
I want to get another key/value pair to my serializer output in the below so that I can get something like this:
{
"total": 1,
"items": [
{
"id": 42920375,
"company": {
"id": 123,
"name": "CompanyName"
},
"project": {
"id": 456,
"name": "ProjectName"
}
}
]
}
But currently, I'm getting:
{
"total": 1,
"items": [
{
"id": 42920375,
"company_id": 5842,
"project_id": 191741,
}
]
}

Answer 1

I don't think you can use ItemsSerializer that way. It needs to correspond to a model.
Active-Model-serializer will automatically serialize each object in an association with its own serializer:
"In your controllers, when you use render :json for an array of objects, AMS will use ActiveModel::ArraySerializer (included in this project) as the base serializer, and the individual Serializer for the objects contained in that array."
So there's no need to reinvent the wheels. Just do this:
render json: paginate(open_items, per_page: 2), status: :ok
Then each item will be processed by ItemSerializer. I don't see a way to add total here though.