ActiveModel as_json のオプション一覧

.as_json(options = nil)

|option名|詳細|
|---|---|---|
|root|trueを指定すると、root要素としてモデル名のkeyが挿入される（ネストがひとつ深くなる）|
|only|要素名の配列を渡すと、その要素のみが出力される|
|except|要素名の配列を渡すと、その要素以外が出力される|
|methods|モデルのメソッド名（配列可）を渡すと、そのメソッドの実行結果が出力される|
|include|アソシエーション名（配列可、ネスト可）を渡すと、その関連情報も一緒に出力される|

root

user.as_json(root: true)
# => { "user" => { 
#        "id" => 1, "name" => "Konata Izumi", "age" => 16, "created_at" => "2006-08-01T17:27:13.000Z", "awesome" => true 
#    } }

only

user.as_json(only: [:id, :name])
# => { "id" => 1, "name" => "Konata Izumi" }

except

user.as_json(except: [:id, :created_at, :age])
# => { "name" => "Konata Izumi", "awesome" => true }

methods

user.as_json(methods: :permalink)
# => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
#      "created_at" => "2006-08-01T17:27:13.000Z", "awesome" => true,
#      "permalink" => "1-konata-izumi" }

include

user.as_json(include: :posts)
# => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
#      "created_at" => "2006-08-01T17:27:13.000Z", "awesome" => true,
#      "posts" => [ { "id" => 1, "author_id" => 1, "title" => "Welcome to the weblog" },
#                   { "id" => 2, "author_id" => 1, "title" => "So I was thinking" } ] }

include(example)

user.as_json(include: { posts: {
                           include: { comments: {
                                          only: :body } },
                           only: :title } })
# => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
#      "created_at" => "2006-08-01T17:27:13.000Z", "awesome" => true,
#      "posts" => [ { "comments" => [ { "body" => "1st post!" }, { "body" => "Second!" } ],
#                     "title" => "Welcome to the weblog" },
#                   { "comments" => [ { "body" => "Don't think too hard" } ],
#                     "title" => "So I was thinking" } ] }

参考