README.md in jb-0.1.1 vs README.md in jb-0.2.0
- old
+ new
@@ -14,18 +14,310 @@
And bundle.
## Usage
-Write a template that contains a Ruby code that returns a Ruby Hash / Array object.
-Then the object will be `to_json`ed to a JSON String.
+Put a template file named `*.jb` in your Rails app's `app/views/*` directory, and render it.
## Features
* No ugly builder syntax
* No `method_missing` calls
* `render_partial` with :collection option actually renders the collection (unlike Jbuilder)
+
+
+## Syntax
+
+A `.jb` template should contain Ruby code that returns any Ruby Object that responds_to `to_json` (generally Hash or Array).
+Then the return value will be `to_json`ed to a JSON String.
+
+
+## Examples
+
+``` ruby
+# app/views/messages/show.json.jb
+
+json = {
+ content: format_content(@message.content),
+ created_at: @message.created_at,
+ updated_at: @message.updated_at,
+ author: {
+ name: @message.creator.name.familiar,
+ email_address: @message.creator.email_address_with_name,
+ url: url_for(@message.creator, format: :json)
+ }
+}
+
+if current_user.admin?
+ json[:visitors] = calculate_visitors(@message)
+end
+
+json[:comments] = {
+ content: @message.comments.content,
+ created_at: @message.comments.created_at
+}
+
+json[:attachments] = @message.attachments.map do |attachment|
+ filename: attachment.filename,
+ url: url_for(attachment)
+end
+
+json
+```
+
+This will build the following structure:
+
+``` javascript
+{
+ "content": "10x JSON",
+ "created_at": "2016-06-29T20:45:28-05:00",
+ "updated_at": "2016-06-29T20:45:28-05:00",
+
+ "author": {
+ "name": "Yukihiro Matz",
+ "email_address": "matz@example.com",
+ "url": "http://example.com/users/1-matz.json"
+ },
+
+ "visitors": 1326,
+
+ "comments": [
+ { "content": "Hello, world!", "created_at": "2016-06-29T20:45:28-05:00" },
+ { "content": "<script>alert('Hello, world!');</script>", "created_at": "2016-06-29T20:47:28-05:00" }
+ ],
+
+ "attachments": [
+ { "filename": "sushi.png", "url": "http://example.com/downloads/sushi.png" },
+ { "filename": "sake.jpg", "url": "http://example.com/downloads/sake.jpg" }
+ ]
+}
+```
+
+To define attribute and structure names dynamically, just use Ruby Hash.
+Note that modern Ruby Hash syntax pretty much looks alike JSON syntax.
+It's super-straight forward. Who needs a DSL to do this?
+
+``` ruby
+{author: {name: 'Matz'}}
+
+# => {"author": {"name": "Matz"}}
+```
+
+Top level arrays can be handled directly. Useful for index and other collection actions.
+And you know, Ruby is such a powerful language for manipulating collections:
+
+``` ruby
+# @comments = @post.comments
+
+@comments.reject {|c| c.marked_as_spam_by?(current_user) }.map do |comment|
+ body: comment.body,
+ author: {
+ first_name: comment.author.first_name,
+ last_name: comment.author.last_name
+ }
+end
+
+# => [{"body": "🍣 is omakase...", "author": {"first_name": "Yukihiro", "last_name": "Matz"}}]
+```
+
+Jb has no special DSL method for extracting attributes from array directly, but you can do that with Ruby.
+
+``` ruby
+# @people = People.all
+
+@people.map {|p| {id: p.id, name: p.name}}
+
+# => [{"id": 1, "name": "Matz"}, {"id": 2, "name": "Nobu"}]
+```
+
+You can use Jb directly as an Action View template language.
+When required in Rails, you can create views ala show.json.jb.
+You'll notice in the following example that the `.jb` template
+doesn't have to be one big Ruby Hash literal as a whole
+but it can be any Ruby code that finally returns a Hash instance.
+
+``` ruby
+# Any helpers available to views are available in the template
+json = {
+ content: format_content(@message.content),
+ created_at: @message.created_at,
+ updated_at: @message.updated_at,
+
+ author: {
+ name: @message.creator.name.familiar,
+ email_address: @message.creator.email_address_with_name,
+ url: url_for(@message.creator, format: :json)
+ }
+}
+
+if current_user.admin?
+ json[:visitors] = calculate_visitors(@message)
+end
+
+json
+```
+
+You can use partials as well. The following will render the file
+`views/comments/_comments.json.jb`, and set a local variable
+`comments` with all this message's comments, which you can use inside
+the partial.
+
+```ruby
+render 'comments/comments', comments: @message.comments
+```
+
+It's also possible to render collections of partials:
+
+```ruby
+render partial: 'posts/post', collection: @posts, as: :post
+
+# or
+
+render @post.comments
+```
+
+You can pass any objects into partial templates with or without `:locals` option.
+
+```ruby
+render 'sub_template', locals: {user: user}
+
+# or
+
+render 'sub_template', user: user
+```
+
+You can of course include Ruby `nil` as a Hash value if you want. That would become `null` in the JSON.
+
+To prevent Jb from including null values in the output, Active Support provides `Hash#compact!` method for you:
+
+```ruby
+{foo: nil, bar: 'bar'}.compact
+
+# => {"bar": "bar"}
+```
+
+If you want to cache a template fragment, just directly call `Rails.cache.fetch`:
+
+```ruby
+Rails.cache.fetch ['v1', @person], expires_in: 10.minutes do
+ {name: @person.name, age: @person.age}
+end
+```
+
+
+## The Generator
+Jb extends the default Rails scaffold generator and adds some .jb templates.
+If you don't need them, please configure like so.
+
+```ruby
+Rails.application.config.generators.jb false
+```
+
+
+## Why is Jb fast?
+
+Jbuilder's `partial` + `:collection` [internally calls `array!` method](https://github.com/rails/jbuilder/blob/83a682aeebde96c6ef02ce742c0b97dc393f5e22/lib/jbuilder/jbuilder_template.rb#L85-L95)
+inside which [`_render_partial` is called per each element of the given collection](https://github.com/rails/jbuilder/blob/83a682aeebde96c6ef02ce742c0b97dc393f5e22/lib/jbuilder/jbuilder_template.rb#L93),
+and then it [falls back to the `view_context`'s `render` method](https://github.com/rails/jbuilder/blob/83a682aeebde96c6ef02ce742c0b97dc393f5e22/lib/jbuilder/jbuilder_template.rb#L100-L103).
+
+So, for example if the collection has 100 elements, Jbuilder's `render partial:` performs `render` method 100 times, and so it calls `find_template` method (which is known as one of the heaviest parts of Action View) 100 times.
+
+OTOH, Jb simply calls [ActionView::PartialRenderer's `render`](https://github.com/rails/rails/blob/49a881e0db1ef64fcbae2b7ddccfd5ccea26ae01/actionview/lib/action_view/renderer/partial_renderer.rb#L423-L443) which is cleverly implmented to `find_template` only once beforehand, then pass each element to that template.
+
+
+## Bencharks
+Here're the results of a benchmark (which you can find [here](https://github.com/amatsuda/jb/blob/master/test/dummy_app/app/controllers/benchmarks_controller.rb) in this repo) rendering a collection to JSON.
+
+### RAILS_ENV=development
+```
+% ./bin/benchmark.sh
+* Rendering 10 partials via render_partial
+Warming up --------------------------------------
+ jb 15.000 i/100ms
+ jbuilder 8.000 i/100ms
+Calculating -------------------------------------
+ jb 156.375 (± 7.0%) i/s - 780.000 in 5.016581s
+ jbuilder 87.890 (± 6.8%) i/s - 440.000 in 5.037225s
+
+Comparison:
+ jb: 156.4 i/s
+ jbuilder: 87.9 i/s - 1.78x slower
+
+
+* Rendering 100 partials via render_partial
+Warming up --------------------------------------
+ jb 13.000 i/100ms
+ jbuilder 1.000 i/100ms
+Calculating -------------------------------------
+ jb 121.187 (±14.0%) i/s - 598.000 in 5.049667s
+ jbuilder 11.478 (±26.1%) i/s - 54.000 in 5.061996s
+
+Comparison:
+ jb: 121.2 i/s
+ jbuilder: 11.5 i/s - 10.56x slower
+
+
+* Rendering 1000 partials via render_partial
+Warming up --------------------------------------
+ jb 4.000 i/100ms
+ jbuilder 1.000 i/100ms
+Calculating -------------------------------------
+ jb 51.472 (± 7.8%) i/s - 256.000 in 5.006584s
+ jbuilder 1.510 (± 0.0%) i/s - 8.000 in 5.383548s
+
+Comparison:
+ jb: 51.5 i/s
+ jbuilder: 1.5 i/s - 34.08x slower
+```
+
+
+### RAILS_ENV=production
+```
+% RAILS_ENV=production ./bin/benchmark.sh
+* Rendering 10 partials via render_partial
+Warming up --------------------------------------
+ jb 123.000 i/100ms
+ jbuilder 41.000 i/100ms
+Calculating -------------------------------------
+ jb 1.406k (± 4.2%) i/s - 7.134k in 5.084030s
+ jbuilder 418.360 (± 9.8%) i/s - 2.091k in 5.043381s
+
+Comparison:
+ jb: 1405.8 i/s
+ jbuilder: 418.4 i/s - 3.36x slower
+
+
+* Rendering 100 partials via render_partial
+Warming up --------------------------------------
+ jb 37.000 i/100ms
+ jbuilder 5.000 i/100ms
+Calculating -------------------------------------
+ jb 383.082 (± 8.4%) i/s - 1.924k in 5.061973s
+ jbuilder 49.914 (± 8.0%) i/s - 250.000 in 5.040364s
+
+Comparison:
+ jb: 383.1 i/s
+ jbuilder: 49.9 i/s - 7.67x slower
+
+
+* Rendering 1000 partials via render_partial
+Warming up --------------------------------------
+ jb 4.000 i/100ms
+ jbuilder 1.000 i/100ms
+Calculating -------------------------------------
+ jb 43.017 (± 9.3%) i/s - 216.000 in 5.080482s
+ jbuilder 4.604 (±21.7%) i/s - 23.000 in 5.082100s
+
+Comparison:
+ jb: 43.0 i/s
+ jbuilder: 4.6 i/s - 9.34x slower
+```
+
+
+### Summary
+
+According to the benchmark results, you can expect 2-30x performance improvement in development env, and 3-10x performance improvement in production env.
## Contributing
Pull requests are welcome on GitHub at https://github.com/amatsuda/jb.