I'm using JBuilder as to return some JSON. I have a index.json.jbuilder that generates the data, and I need to render it to a string. However, I'm not sure how to do this, since: @my_object.to_json and @my_object.as_json don't seem to go through JBuilder.
How could I render the JBuilder view as a string?
I am rendering a collection of users as a json string in the controller like so:
#controllers/users_controller.rb
def index
@users = User.all
@users_json = render_to_string( template: 'users.json.jbuilder', locals: { users: @users})
end
#views/users/users.json.jbuilder
json.array!(users) do |json, user|
json.(user, :id, :name)
end
If the view users.json.jbuilder is at the default path relative to the controller and it cannot find the template, it may be due to a format discrepancy, as it may be trying to look for the html format file. There are two ways to fix this:
Have the client GET /users/index.json
or
Specify the formats option when calling render_to_string (also applies to render):
#controllers/users_controller.rb
def index
@users = User.all
@users_json = render_to_string( formats: 'json' ) # Yes formats is plural
end
This has been verified in Rails 4.1.
You can also do it like this, which leaves your controller a bit cleaner.
# controller
def new
@data = Data.all
end
# view
<% content_for :head do %>
<script type="text/javascript">
var mydata = <%= raw render :partial => 'path/to/partial', :locals => {data: @data} %>;
</script>
<% end %>
# path/to/_partial.html.jbuilder
json.array!(@data) do |d|
json.extract! field1, :field2, :field3, :field4
json.url data_url(d, format: :json)
end
# layouts/application.html
<!DOCTYPE html>
<html>
<head>
<%= yield :head %>
</head>
<body>
...
</body>
</html>
If you're doing this in the controller, a much simpler option is to try to the move the code into the view being rendered by the controller.
I described this here: https://github.com/shakacode/react-webpack-rails-tutorial/blob/master/docs/jbuilder.md
basically you can call render in the view, and you're done. Like this:
<%= react_component('App', render(template: "/comments/index.json.jbuilder"),
generator_function: true, prerender: true) %>
Here's the notes on what happens if you want to pass the data from the controller to the view:
class PagesController < ApplicationController
def index
@comments = Comment.all
# NOTE: The below notes apply if you want to set the value of the props in the controller, as
# compared to he view. However, it's more convenient to use Jbuilder from the view. See
# app/views/pages/index.html.erb:20
#
# <%= react_component('App', render(template: "/comments/index.json.jbuilder"),
# generator_function: true, prerender: true) %>
#
#
# NOTE: this could be an alternate syntax if you wanted to pass comments as a variable to a partial
# @comments_json_sting = render_to_string(partial: "/comments/comments.json.jbuilder",
# locals: { comments: Comment.all }, format: :json)
# NOTE: @comments is used by the render_to_string call
# @comments_json_string = render_to_string("/comments/index.json.jbuilder")
# NOTE: It's CRITICAL to call respond_to after calling render_to_string, or else Rails will
# not render the HTML version of the index page properly. (not a problem if you do this in the view)
# respond_to do |format|
# format.html
# end
end
end
Looking at the source code, it looks like you can do:
json_string = Jbuilder.encode do |json|
json.partial! 'path/to/index', @my_object
end
From console:
view = ApplicationController.view_context_class.new("#{Rails.root}/app/views")
JbuilderTemplate.encode(view){|json| json.partial!('path/to/index', @my_object) }
via https://github.com/rails/jbuilder/issues/84#issuecomment-38109709
in controller you can do like this
def index
json = JbuilderTemplate.new(view_context) do |json|
json.partial! 'index'
end.attributes!
do_something(json)
render json: json
end
note that you need "_index.json.jbuilder" because it calls partial renderer
Following justingordon's tip.
If you are using a React component, you can do the following.
In your controller:
@users = User.all
In your view:
<%= react_component("YourComponentName",
props: render('your_template.json.jbuilder')) %>
This was tested on Rails 5.1.
