granting-write-access-to-others

It's not enough just to allow others to view your projects, you need to allow some people to make changes, too. The goal of this part of the tutorial is to add a "Contributor" checkbox next to each person in the side-bar.

Implementing this is left as an exercise for the reader. The steps are:

1. Add a boolean `contributor` field to the `ProjectMembership` model.
2. Modify the permissions of stories and tasks so that users with `contributor=true` on their project membership have update permission for the project.
3. Use the `<editor>` tag to create an ajax editor for the `contributor` field in the ProjectMembership card.

That's all the hints we're going to give you for this one -- good luck!

Ok, one more hint, here's some associations that might be handy in the Project model:

    has_many :contributor_memberships, :class_name => "ProjectMembership", :scope => :contributor
    has_many :contributors, :through => :contributor_memberships, :source => :user
{: .ruby}

And a helper method that might come in handy when implementing your permission methods:

    def accepts_changes_from?(user)
       user.administrator? || user == owner || user.in?(contributors)
    end
{: .ruby}

app/models/project.rb

@@ -19,14 +19,22 @@ class Project < ActiveRecord::Base
 
   belongs_to :owner, :class_name => "User", :creator => true, :inverse_of => :projects
 
+  has_many :contributor_memberships, :class_name => "ProjectMembership", :scope => :contributor
+  has_many :contributors, :through => :contributor_memberships, :source => :user
+
+  # permission helper
+  def accepts_changes_from?(user)
+    user.administrator? || user == owner || user.in?(contributors)
+  end
+
   # --- Permissions --- #
 
   def create_permitted?
     owner_is? acting_user
   end
 
   def update_permitted?
-    acting_user.administrator? || (owner_is?(acting_user) && !owner_changed?)
+    accepts_changes_from?(acting_user) && !owner_changed?
   end
 
   def destroy_permitted?

app/models/project_membership.rb

@@ -3,6 +3,7 @@ class ProjectMembership < ActiveRecord::Base
   hobo_model # Don't put anything above this
 
   fields do
+    contributor :boolean, :default => false
     timestamps
   end
   attr_accessible 

app/views/taglibs/front_site.dryml

@@ -31,3 +31,12 @@
     <field-list: fields="description, users"/>
   </old-form>
 </extend>
+
+<extend tag="card" for="ProjectMembership">
+  <old-card merge>
+    <body:>
+      <span>Contributor?</span>
+      <editor:contributor/>
+    </body:>
+  </old-card>
+</extend>

db/migrate/20130109032331_project_contributors.rb

@@ -0,0 +1,9 @@
+class ProjectContributors < ActiveRecord::Migration
+  def self.up
+    add_column :project_memberships, :contributor, :boolean, :default => false
+  end
+
+  def self.down
+    remove_column :project_memberships, :contributor
+  end
+end

db/schema.rb

@@ -11,13 +11,14 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20130109030838) do
+ActiveRecord::Schema.define(:version => 20130109032331) do
 
   create_table "project_memberships", :force => true do |t|
     t.datetime "created_at"
     t.datetime "updated_at"
     t.integer  "project_id"
     t.integer  "user_id"
+    t.boolean  "contributor", :default => false
   end
 
   add_index "project_memberships", ["project_id"], :name => "index_project_memberships_on_project_id"