How to serialize relational models as JSON in Ruby on Rails? - ruby-on-rails

Question

Say I have a basic User model:
# Name | Type | Attributes
# ----------------------------- | ------------------ | ---------------------------
# **`id`** | `bigint` | `not null, primary key`
# **`email`** | `string` | `default(""), not null`
# **`encrypted_password`** | `string` | `default(""), not null`
A user can have many companies they manage. So user.rb contains:
has_many :company_permissions
has_many :companies, -> { distinct }, through: :company_permissions
Company is pretty simple:
# Name | Type | Attributes
# ------------------ | ------------------ | ---------------------------
# **`id`** | `bigint` | `not null, primary key`
# **`description`** | `text` |
# **`name`** | `string` |
User and Company are related by a Rails relational model called CompanyPermission:
# Name | Type | Attributes
# ----------------- | ------------------ | ---------------------------
# **`id`** | `bigint` | `not null, primary key`
# **`name`** | `string` |
# **`company_id`** | `bigint` | `not null`
# **`user_id`** | `bigint` | `not null`
A permission's name can be read, write, or delete. If a user has more than 1 permission (e.g. read and write) then there are 2 relational models.
A user can see a JSON response of their current companies:
class CredentialsController < AuthorizedController
def me
render json: current_user, include: %i[companies]
end
end
This produces output like:
{
"id": 676,
"email": "email1#example.com",
"companies": [{
"id": 786,
"name": "Some Company",
"description": "Some Company Description"
}]
}
As you can see, the user doesn't know which permissions they have. I'd like to include the information from CustomerPermission.name here, perhaps something like:
{
"id": 676,
"email": "email1#example.com",
"companies": [{
"id": 786,
"name": "Some Company",
"description": "Some Company Description",
"permissions": ["read", "write"] # <------- I want this
}]
}
Do I need to write an ActiveModel::Serializer from scratch for this? Or is there some other way to easily include this detail from the relational model in the JSON output?

Answer 1

You can do this using github.com/Netflix/fast_jsonapi as Alex mentioned in the comment above.
Keep in mind, this does change the structure to adhere to Google's JSON:API standard. Everything will be nested within the "attributes" property. And when you use include method, it won't include all the data from, for example, Companies - just the id.
Essentially, you need to create a custom method and violate the standard in order to achieve that, but it made total sense in my situations to do that opposed to making multiple API calls.
Create a serializer for your User and Company models, and within that you can define a custom attribute block like:
# app/serializers/user_serializer.rb
class UserSerializer
include FastJsonapi::ObjectSerializer
attribute :companies do |user|
CompanySerializer.new(user.companies).serializable_hash[:data]
end
end
# app/serializers/company_serializer.rb
class CompanySerializer
include FastJsonapi::ObjectSerializer
attribute :permissions do |company|
company.company_permissions.map{|perm| perm.name}
end
end
Hope that helps :)