Dynamically creation of checkboxes

Question

I want to dynamically create checkboxes in a form with the use of an array with users. The value that should be saved to the array (param[:project][:members]) should contain of the user_id's from all the clicked check boxes with users.

I have been looking around a lot but haven't yet found what I look for.

What code should I write for the checkboxes?

Form in view:

<%= form_for @project do |f| %>
    <div class="text_field">
        <%= f.label :title%>
        <%= f.text_field :title%>
    </div>
    <div class="text_field">
        <%= f.label :description%>
        <%= f.text_field :description%>
    </div>
    <div class="dropdown">
        <%= f.label :start_date%>
        <%= f.date_select :start_date %>
    </div>
    <div class="dropdown">
        <%= f.label :end_date%>
        <%= f.date_select :end_date %>
    </div>
    <div class="checkboxes">
        <% @users.each do |user| %>
            // <%= check_box_tag "users[]", user.id %> <--- ???
        <% end %>
    </div>
    <div class="submit">
        <%= f.submit "Spara" %>
    </div>
<% end %>

controller:

def new
  @project = Project.new
  @users = (current_user.blank? ? User.all : User.find(:all, :conditions => ["id != ?", current_user.id]))
end

rendered html:

[ ] Jules Smith    // user_id: 1
[X] Carl Jones     // user_id: 2 
[X] Lily Stevens   // user_id: 3

// param[:project][:members] // <-- 2, 3 (user_id's)

Babur Ussenakunov · Accepted Answer · 2013-02-10 12:33:24Z

2

<% @users.each do |user| %>
    <%= check_box_tag "project[members][]", user.id, checked_or_not, :id => "user_#{user.id}" %> 
    <%= label_tag "user_#{user.id}", user.name_login_or_smth_else %>
<% end %>

Replace checked_or_not with code that indicates that user.id is already in members array. For example if you setup has_and_belongs_to_many relation between projects and users like this:

class Project < ActiveRecord::Base
    has_and_belongs_to_many :members, :class_name => 'User'
end

then form would be:

<% @users.each do |user| %>
    <%= check_box_tag "project[member_ids][]", user.id, @project.member_ids.include?(user.id), :id => "user_#{user.id}" %> 
    <%= label_tag "user_#{user.id}", user.name_login_or_smth_else %>
<% end %>

UPDATE:

Second argument of check_box_tag user.id is the value of checkbox, third @project.member_ids.include?(user.id) is checkbox checked or not. You can read more about it here.

has_and_belongs_to_many adds collection_ids method that returns array of all associated objects’ ids. Since we want to name association members we are setting up association with class_name option:

has_and_belongs_to_many :members, :class_name => 'User'

and collection_ids method becomes member_ids. So @project.member_ids.include?(user.id) sets checkbox checked if members already include user and not checked otherwise.

From another your question I can assume that you setup association like this:

has_and_belongs_to_many :users

Then it will add user_ids method and in form you should use

check_box_tag "project[user_ids][]", user.id, @project.user_ids.include?(user.id)

You can read here for details.

edited Feb 10, 2013 at 12:33

answered Feb 10, 2013 at 10:23

Babur Ussenakunov

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2 Comments

holyredbeard Over a year ago

Thanks a lot for the answer. However, when trying out the code I get the following error: undefined method `member_ids' for... Do you know why? Could you maybe explain "user.id, @project.member_ids.include?(user.id)" for me?

Babur Ussenakunov Over a year ago

Have you setup has_and_belongs_to_many association and checked that is correct and working? I updated my answer.

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