Contentful Rails

A collection of useful things to help make it easier to integrate Contentful into your Rails app. It includes view helpers, a Webhook handler, caching, and a Rails Engine to hook it all together.

This is a work in progress. It relies on the contentful_model gem (http://github.com/contentful/contentful_model)

What is Contentful?

Contentful provides a content infrastructure for digital teams to power content in websites, apps, and devices. Unlike a CMS, Contentful was built to integrate with the modern software stack. It offers a central hub for structured content, powerful management and delivery APIs, and a customizable web app that enable developers and content creators to ship digital products faster.

Configuration

ContentfulRails accepts a block for configuration. Best done in a Rails initializer.

ContentfulRails.configure do |config|
  config.authenticate_webhooks = true # false here would allow the webhooks to process without basic auth
  config.webhooks_username = "a basic auth username"
  config.webhooks_password = "a basic auth password"
  config.access_token = "your access token"
  config.preview_access_token = "your preview access token"
  config.management_token = "your management access token"
  config.space = "your space ID"
  config.environment = "your environment ID"
  config.contentful_options = "hash of options"
end

Note that you don't have to separately configure ContentfulModel - adding the access tokens / space ID / options here will pass to ContentfulModel in an initializer in the Rails engine.

The default is to authenticate the webhooks; probably a smart move to host on an HTTPS endpoint too.

Entry Mapping

By default, ContentfulRails will try to define your entry_mapping configuration for you. It does this by iterating through the descendents of the base class ContentfulModel::Base during initialization. In order to ensure these classes are loaded by this time, it will call eager_load! for the entire application. If this is not desired, you can set the eager_load_entry_mapping config to false set your entry mapping manually by setting the entry_mapping config as described here.

ContentfulRails.configure do |config|
  ...
  config.eager_load_entry_mapping = false
  config.contentful_options = {
    entry_mapping: {
      'article' => Article,
      ...
    }
  }
end

Note: If you do not define the entry mapping in your configuration, the webhook cache expiration will likely not work as expected

Allowing 'Russian Doll' style caching on Entries

The issue with 'Russian Doll' caching in Rails is that it requires a hit on the database to check the updated_at timestamp of an object.

This is obviously expensive when the object is called over an API. So this gem wraps caches updated_at locally, and checks that first on subsequent calls.

Foo.updated_at #returns a timestamp from cache, or from the API if no cache exists

Webhooks Endpoint

If there's a new version of an entry we need to expire the timestamp from the cache.

This gem includes a controller endpoint for Contentful to POST back to.

To make use of this in your app:

routes.rb

Mount the ContentfulRails engine at your preferred url:

mount ContentfulRails::Engine => '/contentful' #feel free to choose a different endpoint name

This will give you 2 routes:

/contentful/webhooks - the URL for contentful to post back to. /contentful/webhooks/debug - a development-only URL to check you have mounted the engine properly :-)

What the webhook handler does

At the moment all this does is delete the timestamp cache entry, which means that a subsequent call to updated_at calls the API.

View Helpers

Contentful has a really nice url-based image manipulation API.

To take advantage of this, there's a custom Redcarpet renderer which allows you to pass the image parameters you want into the call to a parse_markdown() method.

In your application_controller.rb:

helper ContentfulRails::MarkdownHelper

This allows you to call parse_markdown(@your_markdown) and get HTML. Note that out of the box, the parse_markdown() is really permissive and allows you to put HTML in the Contentful markdown fields. This might not be what you want.

Manipulating images

To manipulate images which are referenced in your markdown, you can pass the following into the parse_markdown() call.

parse_markdown(@your_markdown, image_options: { width: 1024, height: 1024 })

The image_options parameter takes the following options (some are mutually exclusive. Read the instructions here):

• :width
• :height
• :fit
• :focus
• :corner_radius
• :quality

Subclassing the MarkdownRenderer class

Sometimes you might want to apply some specific class, markup or similar to an html entity when it's being processed. With RedCarpet that's dead easy.

Just subclass the ContentfulRails::MarkdownRenderer class, and call any methods you need.

class MyRenderer < ContentfulRails::MarkdownRenderer
  # If you want to pass options into your renderer, you need to overload initialize()
  def initialize(opts)
    @options = opts
    super
  end

  # If you want to do something special with links:
  def link(link,title,content)
    # Add a class name to all links, for example
    class_name = "my-link-class-name"
    content_tag(:a, content, href: link, title: title, class: class_name)
  end
end

You can overload any methods exposed in RedCarpet.

Preview API

ContenfulRails can be set up to use the Contenful Preview API, and has the option of protecting that content behind basic authentication. To enable the preview api, add the below settings to your configuration.

ContentfulRails.configure do |config|
  config.enable_preview_domain = true # use the preview domain
  config.preview_access_token = "your preview access token"
  config.preview_username = "a basic auth username"
  config.preview_password = "a basic auth password"
end

If you site is already protected with another form of authentication, then leave preview_username and preview_password unset. This will skip the authentication step when displaying preview content.

To Do

Some things would be nice to do:

• Tests :-)
• Make caching the timestamp optional in the configuration
• Implement a method on ContentfulModel to simulate a parent-child relationship, so we can invalidate caches for parent items

Licence

Licence is MIT. Please see MIT-LICENCE in this repo.

Contributing

Please feel free to contribute!

• Fork this repo
• Make your changes
• Commit
• Create a PR