Based on following models
class Company < ActiveRecord::Base
has_and_belongs_to_many :origins
end
class Origin < ActiveRecord::Base
has_and_belongs_to_many :companies
end
I want to have in my companies/_form a collection of checkboxes representing all origins.
Don't know if the Company.new(params[:company]) in companies_controller#create can create the association between company and the selected origins?
I'm running rails 3.0.0, what is the best way to achieve that?
thanks for your insights
habtm isn't a popular choice these days, it's better to use has_many :through instead, with a proper join model in between. This will give you the method Company#origin_ids= which you can pass an array of origin ids to from your form, to set all the associated origins for #company. eg
<% current_origin_ids = #company.origin_ids %>
<% form_for #company do |f| %>
<label>Name:<%= f.text_field :name %></label>
<% Origin.all.each do |origin| %>
<label><%= origin.name %>
<%= check_box_tag "company[origin_ids][]", origin.id, current_origin_ids.include?(origin.id) %>
</label>
<% end %>
<% end %>
As an aside, using a proper join model, with corresponding controller, allows you to easily add/remove origins with AJAX, using create/delete calls to the join model's controller.
I have to agreed with #carpeliam a has_many :through should not be the default choice. A HABTM works fine and involves less code. It also does not restrict the use of ajax and does expose a origin_ids setter to which you can pass an array of ids. Therefore the screencast, whilst from 2007, still works with Rails 3. The other option if using simple_form is this:
= form.association :origins, :as => :check_boxes
Personally I'm not of the belief that has-many-through is always better, it really depends on your situation. Has-many-through is better if there is ANY possibility of your join model having attributes itself. It's more flexible to change. It removes the magic of some Rails conventions. If however you don't need has-many-through, then there's an old RailsCast for HABTM checkboxes that might come in handy.
Related
I have a Pizza model and Topping model with a PizzaTopping join table. Pizza has many toppings and topping belongs to pizza. I'm a novice with Rails.
My problem is trying to understand how to created a nested form that will add multiple records into my PizzaTopping join table. I also need the toppings to show up in check box form.
<div class="form-horizontal">
<%= form_for(#pizza) do |f| %>
Confusion #1:
To my understand this is to show a full model in check boxes, which works, but I'm confused on how the controller accepts this and creates the records in the join table of the toppings associated with the pizza. I want separate records(and not an attribute that is an array of topping ids):
PizzaTopping.create(id: 1, pizza_id: 1, topping_id: 1)
PizzaTopping.create(id: 2, pizza_id: 1, topping_id: 2)
PizzaTopping.create(id: 3, pizza_id: 1, topping_id: 3)
..
<div class="form-group">
<%= f.collection_check_boxes(:topping_ids, Topping.all, :id, :name) do |b| %>
<%= b.check_box %>
<%= b.label %>
<% end %>
</div>
or Confusion # 2:
This is a nested form but how do I get the toppings in check boxes from the Topping model and same as above, how do I code this in my controller to add records in the join table.
<div class="form-group">
<%= f.fields_for :toppings do |builder| %>
<%= builder.check_box %> // confused what I would even do next
<% end %>
</div>
...
<%= f.submit %>
<% end %>
</div>
First lets setup a indirect many to many relationship though the pizza_toppings table.
class Pizza < ActiveRecord::Base
has_many :pizza_toppings
has_many :toppings, through: :pizza_toppings
end
class Topping < ActiveRecord::Base
has_many :pizza_toppings
has_many :pizzas, through: :pizza_toppings
end
class PizzaTopping < ActiveRecord::Base
belongs_to :pizza
belongs_to :topping
end
What this accomplishes is that it lets you associate any number of pizzas with any number of toppings and ActiveRecord will handle joining for you:
#pizza = Pizza.find_by(name: 'Vesuvio')
#pizza.toppings
# => Topping( name: cheese ) ...
#pizza.toppings << Topping.find_by(name: 'Ham')
# inserts a record into the pizza_toppings table
# you can also do the inverse
#topping = Topping.find_by(name: 'Anchovies')
#topping.pizzas
# => Pizza( name: 'Napoli' )
To setup one to any or many to many relations via a checkbox you can use the collection_check_boxes helper.
<% form_for(#pizza) do |f| %>
<% f.collection_check_boxes(:topping_ids, Topping.all, :id, :name) %>
<% end %>
When you give a model a has_many association it gets a _ids setter which takes an array of ids and adds / removes associations, in this case ActiveRecord is also smart enough to know that it should setup the association through the join table when you use the through option.
The checkboxes generated by collection_check_boxes give you just that - an array in the params containing the ids of the selected toppings.
Note that you don't need to use fields_for here unless you intend to let users create pizzas and toppings on the same page. Also make sure you whitelist the topping_ids param.
def pizza_params
params.require(:pizza).permit(:name, topping_ids: [])
end
And now you got me all hungry.
First things first, if you are using a join table then you need to organise your relations differently, it makes no sense to use a join table with a belongs_to relationship, what you want to do is organise your relations so that a Pizza has_many :toppings, and a Topping has_many :pizzas and use the through: :pizza_toppings key.
Now onto your first confusion,
If you are using checkboxes the most you can hope to receive is the value of that checkbox, most likely the ids, this is then down to you to instantiate the records once you have the array of ids, perhaps something along the lines of selected_toppings = Topping.where(id: params[:topping_ids]) which will instantiate a collection of the toppings that were selected.
Also if you have your relations set up properly there is no need to explicitly create PizzaTopping records, this is a join table, and in my opinion I prefer to handle everything using the relations, something along the lines of pizza.toppings << selected_toppings should do the trick to set it all up.
Confusion two:
I dont think what you are looking for is a nested form, because you are not actually creating toppings, you just want a list of the toppings to relate to a pizza. Nested forms are when you want to create/edit and then write the attributes of a relation, your toppings are already preset, so just simply make checkboxes in the form normally with the values of your toppings ids.
Hope this helps!
I am making my own custom view that I need to make the process of creating associated models less painful for my users. I want to display all of the models associated pieces in-line, with controls to edit them. This is quite easy to roll my own for the basic fields, but I'd rather use a form_filtering_select partial for the inline model's associations, but I can't find any documentation to do this.
You can use Nested Form
Consider a User class which returns an array of Project instances from the projects reader method and responds to the projects_attributes= writer method:
class User
def projects
[#project1, #project2]
end
def projects_attributes=(attributes)
# Process the attributes hash
end
end
Note that the projects_attributes= writer method is in fact required for fields_for to correctly identify :projects as a collection, and the correct indices to be set in the form markup.
When projects is already an association on User you can use accepts_nested_attributes_for to define the writer method for you:
class User < ActiveRecord::Base
has_many :projects
accepts_nested_attributes_for :projects
end
This model can now be used with a nested fields_for. The block given to the nested fields_for call will be repeated for each instance in the collection:
<%= nested_form_for #user do |user_form| %>
...
<%= user_form.fields_for :projects do |project_fields| %>
<% if project_fields.object.active? %>
Name: <%= project_fields.text_field :name %>
<% end %>
<% end %>
...
<% end %>
Here goes the Reference for details.
There's a cool gem out there that does pretty much what you want. It's called Nested Form Fields. It allows you to edit records (along with their has_many associations) on a single page. The cool thing about it is that it even uses jQuery to dynamically add/remove form fields without a page reload. Checkout out the gems docs for proper usage. Hope that helps!
When I use form_for :model the data is saved when I submit the form.
However when I use form_tag, the data is lost after the form is processed.
I need to use form_tag because I have two models in one form.
Is there a way to save form data with form_tag?
You are making two incorrect assumptions in your question. First, form_tag is not necessary or even recommended for multiple-model forms; Second, form_tag doesn't do anything fundamentally different from form_for, you are most likely not formatting the field names correctly for your controller.
In order to create a form with nested models, you need to use the fields_for helper in conjunction with form_for. The relationship needs to be defined first in the model with accepts_nested_attributes_for. Since you have not given us any information about your models, I will give you a made-up example:
class Person < ActiveRecord::Base
has_one :address
accepts_nested_attributes_for :address
end
class Address < ActiveRecord::Base
belongs_to :person
end
This tells ActiveRecord that the Person model can accept attributes for Address, and will pass along the attributes to the correct model to be created.
<% form_for :person do |p| %>
<% p.fields_for :address do |a| %>
use the a form builder to create
fields for the address model here
<% end %>
<% end %>
chaining the fields_for helper from the p form builder lets the helpers generate attributes in the correct format.
More information: Nested Model Forms
Pretty much the same way as before except you'll need to build the params. You can look at your log to see how params are being sent.
eg.
def create
#silly_hat = SillyHat.new( :name => params[:name], :size => params[:size], :colour => params[:colour] )
if #silly_hat.save
...
To simplify things, I have 3 tables :
Person
has_many :abilities, through => :stats
Ability
has_many :people, through => :stats
Stats
belongs_to :people
belongs_to :abilities
Stats has an extra attribute called 'rating'.
What I'd like to do is make an edit person form that always lists all the abilities currently in the database, and lets me assign each one a rating.
For the life of me, I can't figure out how to do this. I managed to get it to work when creating a new user with something like this:
(from the people controller)
def new
#character = Character.new
#abilities = Ability.all
#abilities.each do |ability|
#person.stats.build(:ability_id => ability.id )
end
end
From the people form:
<% for #ability in #abilities do %>
<%= fields_for "person[stats_attributes]" do |t| %>
<div class="field">
<%= t.label #ability.name %>
<%= t.hidden_field :ability_id, :value => #ability.id, :index => nil %>
<%= t.text_field :rating, :index => nil %>
</div>
<% end %>
<% end %>
This successfully gives me a list of abilities with ratings boxes next to them, and lets me save them if i'm making a new user.
The problem is that if I then load up the edit form (using the same form partial), it doesn't bring back the ratings, and if I save, even with the exact same ratings, it creates duplicate entries in the stats table, instead of updating it.
I realize I'm a terrible programmer and I'm probably doing this the wrong way, but how do I get the edit form to recall the current ratings assigned to each ability for that user, and secondly how do i get it to update the rating instead of duplicating it if the combination of person and ability already exists?
Shouldn't that be
Character
has_many :stats
has_many :abilities, through => :stats
Ability
has_many :stats
has_many :characters, through => :stats
Stat
belongs_to :character
belongs_to :ability
?
Also, is it Person or Character? You refer variously to both. (I'm going to go with Character in my answer)
I think you've fallen foul of the "I'll try to make a simplified version of my schema in order to attempt to illustrate a problem but instead make things more complex and muddle the issue by screwing it up so it doesn't make sense" syndrome. Anyway, there's a couple of issues i can see:
1) first thing is that you're adding all the possible abilities to a character as soon as they're created. This is silly - they should start out with no abilities by default and then you create join table records (stats) for the ones they do have (by ticking checkboxes in the form).
2) A simple way to manipulate join records like this is to leverage the "ability_ids=" method that the has_many :abilities macro gives you - referred to as "collection_ids=" in the api http://railsbrain.com/api/rails-2.3.2/doc/index.html?a=M001885&name=has_many
In other words, if you say
#character.ability_ids = [1,12,30]
then that will make joins between that character and abilities 1, 12 and 30 and delete any other joins between that character and abilities not in the above list. Combine this with the fact that form field names ending in [] put their values into an array, and you can do the following:
#controller
def new
#character = Character.new
#abilities = Ability.all
end
#form
<% #abilities.each do |ability| %>
<div class="field">
<%= t.label #ability.name %>
<%= check_box_tag "character[ability_ids][]" %>
</div>
<% end %>
#subsequent controller (create action)
#character = Character.new(params[:character]) #totally standard code
Notice that there's no mention of stats here at all. We specify the associations we want between characters and abilities and let rails handle the joins.
Railscasts episodes 196 and 197 show how to edit several models in one form. Example shown there looks similar to what you're trying to do so it might help you out (same episodes on ascicasts: 196, 197).
Here's my Schema
class Menu < ActiveRecord::Base
belongs_to :menuable, :polymorphic => true
end
class Page < ActiveRecord::Base
has_one :menu, :as => :menuable
end
class Links < ActiveRecord::Base
has_one :menu, :as => :menuable
end
I want to link to a polymorphic class in the Menu view using link_to, e.g.
<%= link_to menu.name, menu.menuable %>
This works, but this retrieves the menuable object from the database, when all I wanted is to generate a link. You can imagine if my menu is large, this will really bog down my application.
When I decared the menuable field as polymorphic, Rails created menuable_type and menuable_id. What can I use to generate a link to the polymorphic page, short of writing a helper function with a giant switch statement (e.g. if I have a large number of menuable 'subclasses'?)
It's been long since the question was asked but I had the same problem recently and the solution was to use polymorphic_url. You need to find the name of the route you need to create a link to, for example "fast_car_path" and make it out of your *_type and *_id from polymorphic table. For example, you have a list of comments and want to make the link to the cars that they belong to. So if *_type = FastCar we have
#comments.each do |comment|
link_to polymorphic_url(comment.commentable_type.tableize.singularize, :id => comment.commentable_id)
which will generate "fast_car_path" without downloading the cars from database.
I am a noob in rails and I dont know how good that advice is, but I hope it will be helpful for somebody.
You could do something like this:
def my_menu_url(menu)
"/#{menu.menuable_type.tableize}/#{menu.menuable_id}"
end
if you use the rails convention for naming the controllers that correspondent to your models.
But don't do it. You work around the routing mechanism of rails and that's simply bad practice.
You should use the :include option in your finders to eager load your menuables:
Menu.all :include => :menuable
In the case this isn't enough you may use some sort of caching.
Another approach could be to use url_for[menu.menuable, menu]. So, the link tag would look like so: <%= link_to menu.name, url_for([menu.menuable, menu]) %>.
you could use polymorphic routes for this
https://api.rubyonrails.org/classes/ActionDispatch/Routing/PolymorphicRoutes.html
<%= link_to menu.name, polymorphic_path(menu.menuable) %>
it will generate html like this
menu.name