Graphql is a alternative to REST architecure which allows client to request the data in particular stucture and it returs data in thbe same
structure.
When you work as a Frontend and Backend team, you might need to setup a server to serve dummy data so that Frontend team can work in parallel.
This post assumes that we already have a bootstrapped project with rails and graphql-ruby. Consider we have some data of users
[
{
"id":1,
"name": "Leanne Graham",
"username": "Bret",
"email": "Sincere@april.biz"
},
{
"id": 2,
"name": "Ervin Howell",
"username": "Antonette",
"email": "Shanna@melissa.tv"
},
{
"id": 3,
"name": "Clementine Bauch",
"username": "Samantha",
"email": "Nathan@yesenia.net"
},
{
"id": 4,
"name": "Patricia Lebsack",
"username": "Karianne",
"email": "Julianne.OConner@kory.org"
}
]
To serve this through the graphql query first we need to setup the UserType.
# app/graphql/types/user_type.rb
module Types
class UserType < Types::BaseObject
graphql_name 'User'
field :id, ID, null: false
field :name, String, null: false
field :username, String, null: false
field :email, String, null: false
end
end
Then lets setup the User model using ActiveModel
# app/model/user.rb
class User
include ActiveModel::Serializers::JSON
attr_accessor :name, :id, :username, :email
def attributes=(hash)
hash.each do |key, value|
send("#{key}=", value)
end
end
def attributes
instance_values
end
end
Setup collection query type
Next, the crucial part on setting the QueryType with custom resolver.
# app/graphql/types/query_type.rb
require 'json'
module Types
class QueryType < Types::BaseObject
field :users, [UserType], null: false, resolve: -> (obj, args, ctx) {
file = File.read File.join(File.dirname(__FILE__), "../data/users.json")
data = JSON.parse(file)
data.map do |user|
g = User.new
g.from_json(user.to_json)
end
}
end
end
Now in your /graphiql interface when you query for
{
users {
id,
name
}
}
you will receive the response
Setup single record query type
Since we already have the UserType and User model we need to add only query type to respond for single record requests.
# app/graphql/types/query_type.rb
require 'json'
module Types
class QueryType < Types::BaseObject
field :user, UserType,
null: false,
resolve: -> (obj, args, ctx) {
file = File.read File.join(File.dirname(__FILE__), "../data/users.json")
data = JSON.parse(file)
selectedUser = data.select do |user|
user['id'].to_i == args[:id]
end.first
user = User.new
user.from_json(selectedUser.to_json)
} do
argument :id, Int, required: true
end
end
The record response will be
The code is available on revathskumar/rails-graphql-activemodel-json
Versions of Language/packages used in this post.
| Library/Language | Version |
| ---------------- |-----------------|
| rails | 5.2.1 |
| ruby | 2.6.0-preview2 |
| graphql (gem) | 1.8.11 |
| graphql-rails | 1.4.11 |