A Deep Dive into append_view_path and prepend_view_path in Ruby on Rails
Tagged under: #ruby-on-rails#views
In the Rails ecosystem, view resolution plays a significant role in how the framework identifies and renders templates. In larger applications, especially those involving plugins or engines, managing the location of views becomes paramount. That’s where the functions
prepend_view_path come into play.
These are two public methods provided by the
ActionController::Base class, allowing developers to manipulate the order in which Rails looks up views in directories.
append_view_path(path): This method adds the specified path to the end of the view load path.
prepend_view_path(path): Contrarily, this method adds the specified path to the beginning of the view load path.
Why Use Them?
By manipulating the view lookup path, developers can:
Share partials across different parts of an application. Override views provided by Rails engines or plugins. Structure large applications to ensure views are organized and easily discoverable. Code Samples
- Basic Usage
In a Rails controller:
class MyController < ApplicationController before_action :set_custom_path def set_custom_path prepend_view_path "app/views/custom" end end
In this example, any view lookup inside
MyController would first search the
app/views/custom directory before searching the standard view directories.
- Overriding Engine Views
Suppose you’re using a Rails engine called “MyEngine” that provides default views. If you want to override these views without modifying the engine, you can:
class ApplicationController < ActionController::Base before_action :override_engine_views def override_engine_views prepend_view_path "app/views/overrides/my_engine" end end
By adding a
prepend_view_path, Rails will look in the
app/views/overrides/my_engine directory first, allowing you to provide custom views that will override the ones in the engine.
- Sharing Partials
If you have common partials that you want to be accessible across your entire application:
class ApplicationController < ActionController::Base before_action :set_shared_partials_path def set_shared_partials_path append_view_path "app/views/shared" end end
By appending this path, you can reference shared partials from anywhere in the application without specifying the full path.
- Avoid Overusing: Modifying the view path can be powerful, but if overused, it can make your application harder to understand. Use it sparingly and document your intentions.
- Be Explicit: When overriding views, especially from engines, name your directories clearly to indicate what’s being overridden.
- Mind the Order: Remember,
prepend_view_pathmakes Rails look in the specified directory first, and
append_view_pathmakes it look there last. This order determines the precedence of your views. Conclusion
Manipulating the view lookup path in Rails with
prepend_view_path provides developers with additional flexibility in structuring and organizing large applications, as well as in integrating plugins and engines. Used judiciously, these tools can help ensure your Rails app remains organized and maintainable.