Custom Form Elements in Rails - ruby-on-rails

So I'm new to Rails and I'm trying to figure out what the canonical way to add custom form elements is. Currently the way I'm doing it is super grotty.
module ActionView
module Helpers
module FormOptionsHelper
def some_new_field(object, method, options = {}, html_options = {})
#code code
end
end
class FormBuilder
def contract_year_select(method, options = {}, html_options = {})
#template.some_new_field(#object_name, method, objectify_options(options), #default_options.merge(html_options))
end
end
end
end
I have seen this however.
class Forms::ApplicationFormBuilder < ActionView::Helpers::FormBuilder
Forms::ApplicationHelper.instance_methods.each do |selector|
src = <<-end_src
def #{selector}(method, options = {})
#template.send(#{selector.inspect}, #object_name, method, objectify_options(options))
end
end_src
class_eval src, __FILE__, __LINE__
end
private
def objectify_options(options)
#default_options.merge(options.merge(:object => #object))
end
end
(from here)
Extending FormBuilder seems like a better solution than duck punching it. Is there some other way to do this that doesn't require directly copying parts of the FormBuilder class into my custom one?

Two parter here:
First, as someone new to rails, I would recommend using the Formtastic gem.
V is the abused and neglected part of MVC in rails.
Formtastic is very well tested and has support for Rails 3
https://github.com/justinfrench/formtastic
With Formtastic you can then create custom elements extending it's brilliant class and get a whole host of other benefits beyond simple field display.
Second, extending the class is definitely acceptable. I prefer the Module method as it's easier to look at. Like something along the lines of:
module Forms::ApplicationFormBuilder
class WhateverYourExtending
def some_special_method(stuff)
# all kinds of special stuff here
end
end
end
But I barely know what I am talking about here... This stuff is right on the edge of my understanding.
Just saw you talking about forms and I love Formtastic!

Related

Reload dynamically defined helpers

I want to define view helpers in Rails 5.2.0 on runtime (from within some code that lies within my lib folder and / or some initializer) and I came up with this approach so far:
def new_module
Module.new do
def self.create_method(name, &block)
define_method(name, &block)
end
end
end
def define_dynamic_helper(name, &block)
helpers = new_module
helpers.create_method(name, &block)
ActionView::Base.send :include, helpers
end
Now that I can define dynamic modules that get include into ActionView::Base on runtime, I call them e.g. in my controller like this:
define_dynamic_helper("my_helper") do
"some data"
end
And my view uses the helper like this
<%= my_helper %>
But this has a drawback during development: When I remove the line that defines my helper, it is still available but I would expect a MethodMissing error. And as you can guess, this can lead to very complicated situations to debug.
So I got two questions here:
Is it possible to completely remove all dynamic helpers when Rails does a reload during development? Is there some kind of hook I can use?
Is using ActionView::Base.send :include, helpers the right approach for this? Or is there another entry point that I could use (which maybe provides a better reloading approach?)

Rails: Make Route Helper Methods Available to PORO

Within a Plain Old Ruby Object (PORO) in my rails app: I have the following method:
def some_method
content_tag(:li, link_to("Do something", somewhere_path(object.id)))
end
First: the object didn't understand the method content_tag, so I added the following which made the object understand that method:
include ActionView::Helpers::TagHelper
Then the object didn't understand link_to so I added the following which made the object understand that method:
include ActionView::Helpers::UrlHelper
Now, it doesn't understand my route: somewhere_path(object.id).
Question: How can I make the PORO in my rails app understand the helpers which generate routes?
Followup Question: Is there an easier way to include all of this functionality into my PORO object? Perhaps there is a way to only include one major module and get all of this functionality (as opposed to perhaps needing to require 3 different modules).
You either have to do what you describe in your self-answer (link to revision I refer to), or inject some context into your POROs. Where context is something which knows all those methods. Something like this:
class ProjectsController
def update
project = Project.find(params[:id])
presenter = Presenters::Project.new(project, context: view_context) # your PORO
# do something with presenter
end
end
And your PORO would look like this:
module Presenters
class Project
attr_reader :presentable, :context
def initialize(presentable, context:)
#presentable = presentable
#context = context
end
def special_link
context.somewhere_path(presentable)
end
end
end
Me, I like neither of them. But sometimes we have to choose a lesser evil.
If anyone happens to know of a current way to get access to all of these methods with one include statement then let me know.
Why, yes. There is a way.
module MyViewCompatibilityPack
include ActionView::Helpers::TagHelper
include ActionView::Helpers::UrlHelper
def url_helpers
Rails.application.routes.url_helpers
end
end
class MyPoro
include MyViewCompatibilityPack
...
end
The issue is that actionview-related methods are not available to POROs.
In order to get all the great stuff from actionview: you need to utilize the view_context keyword. Then: you can simply call upon actionview-related methods from your view_context:
class BuildLink
attr_accessor :blog, :view_context
def initialize(blog, view_context)
#blog = blog
#view_context = view_context
end
def some_method
content_tag(:li, link_to(“Show Blog“, view_context.blog_path(blog)))
end
end
So for example: from your controller you would call upon this PORO like so:
BuildLink.new(#blog, view_context).some_method
For more information, see below references:
Rails doc on view_context
Utilization of view_context via presenter pattern, shown in this article
Railscast which talks through utilizing view_context via presenter pattern

Recommended way to use Rails view helpers in a presentation class

I've been researching the 'recommended' way to use Rails view helpers (e.g. link_to, content_tag) in a plain ruby class, such as a presenter. It seems there's very little information on this front and I wanted to get an idea of what the Stack community thought.
So, the options we have are.. (note I'm using Rails 4, and am less concerned about older versions)
Include the required modules manually
This is probably the cleanest way, since only the helpers needed are included. However I have found this method to not work in some cases, as the usual view context provided in plain Rails helpers is configured for the current request. url_for wouldn't know about the current request for example, so the host might not match.
class MyPresenter
include ActionView::Helpers::UrlHelper
include ActionView::Helpers::CaptureHelper
def wrapped_link
content_tag :div, link_to('My link', root_url)
end
end
Use ActionController::Base.helpers
Since Rails 3, ActionController::Base has included a helpers method to access the current view context. I believe the view context provided by this method is configured as it would be in a rails helper, but I might be wrong. There's not really any documentation about this which seems worrying, but it does work quite well in practice.
class MyPresenter
def wrapped_link
h.content_tag :div, h.link_to('My link', h.root_url)
end
protected
def h
ActionController::Base.helpers
end
end
I believe this view context can also be mixed in with include, but the rails view helpers have hundreds of methods and it feels dirty to include them all indiscriminately.
Inject the view context when calling the presenter
Finally, we could just pass the view context to the class when it's initialized (or alternatively in a render method)
class MyPresenter
attr_accessor :context
alias_method :h, :context
def initialize(context)
#context = context
end
def wrapped_link
h.content_tag :div, h.link_to('My link', h.root_url)
end
end
class MyController < ApplicationController
def show
# WARNING - `view_context` in a controller creates an object
#presenter = MyPresenter.new(view_context)
end
end
Personally I tend to lean towards the latter two options, but with no definitive answer from the Rails team (that I've been able to find) I felt a bit unsure. Who better to ask than Stack!
I would go with the mix of the second and third option, something like:
class MyPresenter
def initialize(helpers)
#h = helpers
end
def wrapped_link
h.content_tag :div, h.link_to('My link', h.root_url)
end
private
attr_reader :h
end
Your second option require all your unit tests to be stubbed as ActionController::Base.helpers which maybe isn't a good option and your third option you're using a huge context to access just some methods.
I would really make that dependent on what kind of methods you use. If it's just the basics like content_tag etc. I would go for the ActionController::Base.helpers way. It is also possible to call some helpers directly, e.g. for paths inside models I almost always use something along the lines of Rails.application.routes.url_helpers.comment_path.
For controller-specific stuff the third option might be useful, but personally the "pure" way seems nicer. Draper has an interesting approach too: They save the view_context for the current request and then delegate the calls to h-helpers to it: https://github.com/drapergem/draper/blob/master/lib/draper/view_context.rb
It really is just a matter of preference. I would never include all helpers at once, as you already said. But the second option is quite nice if you want to build the presentation layer yourself without using a gem like Draper or Cells.

Using Decorator pattern in Rails but can't access view helper

I'm trying to implement Decorators using the learnings from "Rails 4 Patterns" Code School course, but I'm running into trouble as I need a view helper in the Decorator class.
I want my view to have:
<%= #model_decorator.previous %>
Then in the decorator:
def previous
if object.prev_item.nil?
"Previous"
else
link_to("Previous", object)
end
end
The course suggests you make a call to the decorator within your view helper in the view file itself, but that's no good if the logic could output one result with a helper and one without. (i.e. need the output to be a link or not).
I've tried using helpers.link_to but it errors out as not providing the correct information for the url_for option. I've confirmed link_to("Previous", object) works within the view itself.
For Rails 4
include ActionView::Helpers::UrlHelper
link_to("Previous", Rails.application.routes.url_helpers.send("#{object.class.name.underscore}s_path".to_sym, object))
As for me it`s better to make a decorator for it:
class LinkDecorator
include ActionView::Helpers::UrlHelper
def initialize(label, object)
#label = label
#object = object
end
def show
link_to(label, url_helpers.send("#{object.class.name.underscore}s_path".to_sym, object))
end
def index
link_to(label, url_helpers.send("#{object.class.name}s_path".to_sym))
end
...
private
attr_reader :label, :object
def url_helpers
Rails.application.routes.url_helpers
end
end
Example usage:
LinkDecorator.new(object.name, object).show
If I understand your problem correctly, you essentially want links in a plain old ruby object.
My solution would be this:
include ActionView::Helpers::UrlHelper
link_to("Previous", Rails.application.routes.url_helpers.objects_path(object))
# assuming the object is always of one class
If the object is of a different class, than it would be possible to use the .send method to send the correct message to app ie.:
include ActionView::Helpers::UrlHelper
link_to("Previous", Rails.application.routes.url_helpers.send("#{object.class}s_path".downcase.to_sym, object))
# I'd create a function out of that line to make it a bit neater
It sounds like the error thrown by url_for comes from missing the routes and there's a few ways to include those. My solution kinda avoids that problem by using Rails.application.routes.url_helpers. Hope this helps!

How to override sprockets paths in rails?

I'm trying to override the path that Sprockets produces in Rails, particularly for the sass helpers.
I've gotten somewhere using various solutions:
a) overriding the image_tag helpers in the views
b) overriding ActionView::AssetPaths compute function
c) including new module in Sass::Script::Functions
But it feels like there should be a much simpler way than doing all this. Is there a nice way
to decorate the sprockets paths? I'm doing this because we have some custom url and packaging stuff happening.
So, in the end I found this message buried in sprockets/context.rb
Custom asset_path helper is not implemented
Extend your environment context with a custom method.
environment.context_class.class_eval do
def asset_path(path, options = {})
end
end
Which would seem to suggest that Rails.application.assets.context_class.class_eval would
allow me to change the asset_path handler, but it didn't seem to work. I'm not sure if that's my fault or not, as I couldn't find any examples of this.
Currently my hack to get this working is this:
ActionView::AssetPaths.class_eval do
def compute_public_path(source, dir, options = {})
my_transform(source)
end
end
Sprockets::Helpers::RailsHelper::AssetPaths.class_eval do
def compute_public_path(source, dir, options = {})
my_transform(source)
end
end
ActionView::Helpers::AssetTagHelper::AssetPaths.class_eval do
def compute_public_path(source, dir, options = {})
my_transform(source)
end
end
I suspect I don't need all three of these, but I'm not sure. Anybody who knows their sprockets want to comment on this?

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