JSON Mapping

This recipe will help you to setup a basic JSON Mapping in your application.
First you need an amber project generated with Amber CLI or from scratch.
You can use JSON.mapping to directly create an object from JSON:
src/controllers/some_controller.cr
class User
  JSON.mapping(
    username: String,
    password: String,
  )
end
​
class SomeController < ApplicationController
  def json_mapping
    return "empty body" if request.body.to_s.blank?
    context.response.content_type = "application/json"
    user = User.from_json request.body.to_s
    user.username += "mapped!"
    user.to_json
  end
end
Then in your routes file:
config/routes.cr
Amber::Server.configure do |app|
  pipeline :web do
    # pipelines...
  end
​
  routes :web do
    # other routes,,,
    get "/json_mapping", SomeController, :json_mapping
  end
end
Alternatively you can use response_with helper. Here you don't need to setup content_type, however the requested path requires a .json extension, by example /json_mapping.json
class SomeController < ApplicationController
  def json_mapping
    return "empty body" if request.body.to_s.blank?
    user = User.from_json request.body.to_s
    user.username += "mapped!"
    response_with do
      json user.to_json
    end
  end
end
Also see Response With and Response & Request.
JSON API
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