How to use plain Ruby object with url helpers - ruby-on-rails

I am rendering a page from a simple custom model (not ActiveRecord, plain ActiveModel) and I cannot get the url/path helpers to generate an url with their id, like this:
person_path(model)
# I want: /person/3
# I get: /person
Is there any concrete class I must inherit or function to implement so the url helpers work with my custom model?
I heard about to_param but it is not working, at least not with this:
class Person
include ActiveModel::Model
def id
3
end
def to_param
id.to_s
end
end
According the documentation that should work:
Any class that includes ActiveModel::Model can be used with form_for,
render and any other Action View helper methods, just like Active
Record objects.
But I guess there is still a missing function needed for the url helpers to work

You need to define a persisted? method that returns true: the default implementation always returns false, which causes rails to generate a path with no id.

It would be good if you can share the code from config/routes.rb or at least the result from rake routes.
Double check your routes again. I think you may have defined the route as a singular resource resource :person which will not add an ID to the url.

Related

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!

Overriding Rails Default Routing Helpers

I'm writing an app where I need to override the default routing helpers for a model. So if I have a model named Model, with the corresponding helper model_path() which generates "/model/[id]". I'd like to override that helper to generate "/something/[model.name]". I know I can do this in a view helper, but is there a way to override it at the routing level?
You can define to_param on your model. It's return value is going to be used in generated URLs as the id.
class Thing
def to_param
name
end
end
The you can adapt your routes to scope your resource like so
scope "/something" do
resources :things
end
Alternatively, you could also use sub-resources is applicable.
Finally you need to adapt your controller as Thing.find(params[:id]) will not work obviously.
class ThingsController < ApplicationController
def show
#thing = Thing.where(:name => params[:id).first
end
end
You probably want to make sure that the name of your Thing is unique as you will observe strange things if it is not.
To save the hassle from implementing all of this yourself, you might also be interested in friendly_id which gives you this and some additional behavior (e.g. for using generated slugs)
You need the scope in routes.rb
scope "/something" do
resources :models
end

Extending model to include "helper" methods

I have a kind of social network website.
I have a logic to create the path for the user, and select an avatar for each user described in UsersHelper methods user_path(user) and user_avatar(user).
Instead I want to have methods like user.path and user.avatar, but I don't want to have that code inside the model file.
I tried extending the User class inside the helper:
module UsersHelper
class User
def avatar
...
end
end
end
That doesn't work - the method I added aren't recognized (I'm guessing Rails dynamically generates the ActiveRecord class on demand so my methods don't apply?)
I'd really appreciate ideas
First, there's a reason helpers are separated from models. According to the MVC pattern your model shouldn't know anything about your helpers, and not vice versa either (the latter is usually ignored in Rails, though).
But, if you want to do this, you need to do class ::User in model UsersHelper, or the following:
module UsersHelper
end
class User
end
The reason for this is that Ruby namespaces classes. So you defined UsersHelper::User, while your model is called User. Calling the class ::User or defining it outside the module forces it into the root namespace.
However, as I said, this is not the "correct" way to do it. A better way would be how you're already doing it, or maybe using a decorator pattern.
Draper is an awesome little gem that does an excellent job of achieving the functionality you're looking for (adding view / presentation specific code while still making it "feel" like the model you're working with). We've removed almost all of our model-specific helpers after starting to use draper.
Basically, it works by defining decorators, which work like a wrapper around your model. A decorator looks and feels like the model it's decorating, but can have additional functionality defined on top of it. In addition, you can restrict access to certain fields and lock stuff down if you like.
For your example, adding a decorator would be as simple as:
(in app/decorators/user_decorator.rb)
class UserDecorator < ApplicationDecorator
decorates :user
def avatar
# your implementation
end
(in your controller)
def index
respond_with UserDecorator.decorate(User.all)
end
(in your views)
<div class='avatar'><%= user.avatar %></div>
<div class='name'><%= user.name %></div>
Helpers are intended to use with the views, not with the models.
If you wish to have something like user.avatar, you have to add it to your model.
If you want to stick it in the helpers, then in the UsersHelper add a user_avatar method.

Pretty Paths in Rails

I have a category model and I'm routing it using the default scaffolding of resources :categories. I'm wondering if there's a way to change the paths from /category/:id to /category/:name. I added:
match "/categories/:name" => "categories#show"
above the resources line in routes.rb and changed the show action in the controller to do:
#category = Category.find_by_name(params[:name])
it works, but the 'magic paths' such as link_to some_category still use the :id format.
Is there a way to do this? If this is a bad idea (due to some possible way in which rails works internally), is there another way to accomplish this? So that /categories/music, for example, and /categories/3 both work?
Rails has a nifty model instance method called to_param, and it's what the paths use. It defaults to id, but you can override it and produce something like:
class Category < ActiveRecord::Base
def to_param
name
end
end
cat = Category.find_by_name('music')
category_path(cat) # => "/categories/music"
For more info, check the Rails documentation for to_param.
EDIT:
When it comes to category names which aren't ideal for URLs, you have multiple options. One is, as you say, to gsub whitespaces with hyphens and vice versa when finding the record. However, a safer option would be to create another column on the categories table called name_param (or similar). Then, you can use it instead of the name for, well, all path and URL related business. Use the parameterize inflector to create a URL-safe string. Here's how I'd do it:
class Category < ActiveRecord::Base
after_save :create_name_param
def to_param
name_param
end
private
def create_name_param
self.name_param = name.parameterize
end
end
# Hypothetical
cat = Category.create(:name => 'My. Kewl. Category!!!')
category_path(cat) # => "/categories/my-kewl-category"
# Controller
#category = Category.find_by_name_param(param[:id]) # <Category id: 123, name: 'My. Kewl. Category!!!'>
If you don't want to to break existing code that relying on model id you could define your to_param like this:
def to_param
"#{id}-#{name}"
end
so your url will be: http://path/1-some-model and you still can load your model with Model.find(params[:id]) because:
"123-hello-world".to_i
=> 123
Although possibly more than you need, you may also want to look into 'human readable urls' support like friendly_id or one of the others (for instance, if you need unicode support, etc.) that are described here at Ruby Toolbox.

Rails routing - custom routes for Resources

I'm building currently one Rails app and I'd like to stick to all those fancy things like REST and Resources, but I'd like to customise my routes a little. I want my GET route to be little more verbose - the app I'm creating is a simple blog, so instead of GET /posts/1 I'd prefer something like GET /posts/1-my-first-post.
Any ideas how to do this? Didn't find anything on the web.
Routes:
map.resources :posts
Model:
class Post < ActiveRecord::Base
def to_param
"#{id.to_s}-#{slug}"
end
end
Should do the trick.
Btw: http://railscasts.com/episodes/63-model-name-in-url
Define a to_param method in your Model and all the url helpers will youse what you return with that method, e.g.:
class Post < ActiveRecord::Base
der to_param
slug
end
end
You will also need to adapt your controllers for that. Replace:
Post.find(params[:id])
with:
Post.find_by_slug(params[:id])
Also note that the find method raises ActiveRecord::RecordNotFound exception when the record can't be found while using the find_by_* method no Exceptions will be raised so you need to check that manually.
You could find the friendly_id plugin useful as it will also handle redirections if you rename your slugs (thus seo friendly), handles name collisions and seamlessly integrates with the find method so you don't need to touch your controller methods (except for the redirection thingy).
Alternatively...
Add a method like this to post.rb
def path
"/posts/#{id}-#{slug}"
end
Then use the following in your views:
Alternatively...
Add a method like this to application_helper.rb
def permalink(post)
"#{post_path(post)}-#{post.slug}"
end
Then use the following in your views (using permalink(#post) instead of post_path)
<%= link_to #post.title, permalink(#post) %>

Resources