# nestive-rails

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This gem is a continuation for Rails 5 of the [nestive](https://github.com/rwz/nestive) gem originally created by Justin French and Pavel Pravosud.

nestive-rails adds powerful layout and view helpers to your Rails app. It's similar to the nested layout technique [already documented in the Rails guides](http://guides.rubyonrails.org/layouts_and_rendering.html#using-nested-layouts) and found in many other nested layout plugins (a technique using `content_for` and rendering the parent layout at the end of the child layout). There's a bunch of problems with this technique, including:

* you can only *append* content to the content buffer with `content_for` (you can't prepend to content, you can't replace it)
* when combined with this nested layout technique, `content_for` actually *prepends* new content to the buffer, because each parent layout is rendered *after* it's child

nestive-rails is *better* because it addresses these problems.

---

## Table of Contents

* [Installation](#installation)
* [Usage](#usage)
   * [Declaring an area of content with `area`](#declaring-an-area-of-content-with-area)
   * [Appending content to an area with `append`](#appending-content-to-an-area-with-append)
   * [Prepending content to an area with `prepend`](#prepending-content-to-an-area-with-prepend)
   * [Replacing content with `replace`](#replacing-content-with-replace)
   * [Removing content with `purge`](#removing-content-with-purge)
   * [Extending a layout in a child layout (or view) with `extends`](#extending-a-layout-in-a-child-layout-or-view-with-extends)
* [Example](#example)
* [Caching](#caching)
* [To Do](#to-do)
* [Contributing](#contributing)
    * [Contributors](#contributors)
* [License](#license)

---

## Installation

`nestive-rails` works with Rails 5.0 onwards. You can add it to your `Gemfile` with:

```ruby
gem 'nestive-rails'
```

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install nestive-rails

If you always want to be up to date fetch the latest from GitHub in your `Gemfile`:

```ruby
gem 'nestive-rails', github: 'jonhue/nestive-rails'
```

## Usage

### Declaring an area of content with `area`

The `area` helper is a lot like Rails' own `<%= yield :foo %>`, and is used in layouts to define and render a chunk of content in your layout:

```erb
<%= area :sidebar %>
```

Unlike `yield`, `area` will allow your parent layouts to add content to the area at the same time using either a String or a block:

```erb
<%= area :sidebar, "Some Content Here" %>

<%= area :sidebar do %>
    Some Content Here
<% end %>
```

It's important to note that this isn't *default* content, it *is* the content (unless a child changes it).

### Appending content to an area with `append`

The implementation details are quite different, but the `append` helper works much like Rails' built-in `content_for`. It will work with either a String or block, adding the new content onto the end of any content previously provided by parent layouts:

```erb
<%= extends :application do %>
    <% append :sidebar, "More content." %>
    <% append :sidebar do %>
        More content.
    <% end %>
<% end %>
```

### Prepending content to an area with `prepend`

Exactly what you think it is. The reverse of `append` (duh), adding the new content at the start of any content previously provided by parent layouts:

``` erb
<%= extends :application do %>
    <%= prepend :sidebar, "Content." %>
    <%= prepend :sidebar do %>
        Content.
    <% end %>
<% end %>
```

### Replacing content with `replace`

You can also replace any content provided by parent layouts:

``` erb
<%= extends :application do %>
    <%= replace :sidebar, "New content." %>
    <%= replace :sidebar do %>
        New content.
    <% end %>
<% end %>
```

### Removing content with `purge`

You can remove the content in the single or in multiple areas

``` erb
<% purge :sidebar %>
<% purge :sidebar, :banner %>
```

... which is equal to:

``` erb
<% replace :sidebar, nil %>
```

### Extending a layout in a child layout (or view) with `extends`

Any layout (or view) can declare that it wants to inherit from and extend a parent layout, in this case we're extending `app/views/layouts/application.html.erb`:

``` erb
<%= extends :application do %>
   ...
<% end %>
```

You can nest many levels deep:

`app/views/layouts/application.html.erb`:

``` erb
<!DOCTYPE html>
<html>
    <head>
        <%= area :head do %>
            <title><%= area :title, 'Nestive' %></title>
        <% end %>
    </head>
    <body>
        <%= yield %>
    </body>
</html>
```

`app/views/layouts/with_sidebar.html.erb`:

``` erb
<%= extends :application do %>
    <div class="sidebar"><%= area(:sidebar) do %>
        here goes sidebar
    <% end %></div>
    <%= yield -%>
<% end %>
```

`app/views/layouts/blog_posts.html.erb`:

``` erb
<%= extends :with_sidebar do %>
    <% append :sidebar do %>
        Blog archive:
        <%= render_blog_archive %>
    <% end %>

    <% append :head do %>
        <%= javascript_include_tag 'fancy_blog_archive_tag_cloud' %>
    <% end %>

    <%= yield %>
<% end %>
```

---

## Example

Set-up a global layout defining some content areas.

`app/views/layouts/application.html.erb`:

``` erb
<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title><%= area :title, "JustinFrench.com" %></title>
        <meta name="description" content="<%= area :description, "This is my website." %>">
        <meta name="keywords" content="<%= area :keywords, "justin, french, ruby, design" %>">
    </head>
    <body>
        <div id="wrapper">
            <div id="content">
                <%= area :content do %>
                    <p>Default content goes here.</p>
                <% end %>
            </div>
            <div id="sidebar">
                <%= area :sidebar do %>
                    <h2>About Me</h2>
                    <p>...</p>
                <% end %>
            </div>
        </div>
        <%= yield %>
    </body>
</html>
```

Next, we set-up a `blog` layout that extends `application`, replacing,
appending & prepending content to the areas we defined earlier.

`app/views/layouts/blog.html.erb`:

``` erb
<%= extends :application do %>
    <% replace :title, "My Blog – " %>
    <% replace :description, "Justin French blogs here on Ruby, Rails, Design, Formtastic, etc" %>
    <% prepend :keywords, "blog, weblog, design links, ruby links, formtastic release notes, " %>
    <%= yield %>
<% end %>
```

Now in our blog index view we can use `blog` layout and fill in the areas with
content specific to the index action.


`app/views/posts/index.html.erb`:

``` erb
<% replace :content do %>
    <h1>My Blog</h1>
    <%= render @articles %>
<% end %>

<% append :sidebar do %>
    <h2>Blog Roll</h2>
    <%= render @links %>
<% end %>
```

We also need to instruct the `PostsController` to use this `blog` layout:

`app/controllers/posts_controller.rb`:

``` ruby
class PostsController < ApplicationController
    layout 'blog'
end
```

---

## Caching

nestive-rails works the same way `content_for` does and has the same caching drawbacks. That means that nestive-rails helpers are completely ignored when called from within cached block. You probably don't want to use fragment caching around dynamic nestive-rails areas and have to be extra careful what and how you cache to avoid unpleasant surprises.

---

## To Do

[Here](https://github.com/jonhue/nestive-rails/projects/1) is the full list of current projects.

To propose your ideas, initiate the discussion by adding a [new issue](https://github.com/jonhue/nestive-rails/issues/new).

---

## Contributing

We hope that you will consider contributing to `nestive-rails`. Please read this short overview for some information about how to get started:

[Learn more about contributing to this repository](https://github.com/jonhue/nestive-rails/blob/master/CONTRIBUTING.md), [Code of Conduct](https://github.com/jonhue/nestive-rails/blob/master/CODE_OF_CONDUCT.md)

### Contributors

Give the people some :heart: who are working on this project. See them all at:

https://github.com/jonhue/nestive-rails/graphs/contributors

## License

MIT License

Copyright (c) 2017 Jonas Hübotter

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.