In Rails how do I display only the value of a hash item within an array?

Question

I'm new to ruby/rails and trying to build a simple Projects / Tags app where Projects and Tags are associated as has_and_belongs_to_many to each other. It's basically a simple list of projects that have tags associated, and those tags in turn can be re-used by multiple projects.

I've been loading tags into projects like this:

my_project = Project.create(:name => "My Project")
my_tag = Tag.create(:content => "My Tag")
my_project.tags << my_tag

All appears well until I try to load the info into my View. I have a list of projects, each with a small table below that lists the associated tags:

<table>
 <% @projects.each do |project| %>
   <table>
     <tr>
       <td width="300"><%= project.name %></td>
       <td width="100"><%= link_to 'Edit project', edit_project_path(project) %></td>
       <td width="100"><%= link_to 'Nuke project', project, :confirm => 'Are you sure?', :method => :delete %></td>
     </tr>
   </table>
   <table>
     <tr>
       <td><%= project.tags %></td>
     </tr>
   </table>
 <% end %>
</table>

The View output I get is:

[1] My Project               Edit Project      Nuke Project
[2] [#<Tag id: 1, content: "My Tag", created_at: "2012-03-27 19:27:26", updated_at: "2012-03-27 19:27:26">, #<Tag id: 2, content: "My Other Tag", created_at: "2012-03-27 19:41:04", updated_at: "2012-03-27 19:41:04">]

In line [2] How do I go about only displaying the values of :content and not the entire hash? Also - is this how I should associate tags with projects?

Would be great if anyone could point me in the right direction. Much appreciated!!

Thanks! Jason

Answer 1

Well project.tags will return an array, so you need to loop over each item and display it. For example try:

project.tags.map {|tag| tag.content}.to_sentence

Map loops through each tag, and we're displaying the content of each tag, finaly outputting it to a sentence.

There are numerous other ways to do that. Have a look at the array methods for more info.

About the other question, has_and_belongs_to_many is fine, but for more flexibility try using has_many :through, as explained here . And here is the reasoning behind that.

Answer 2

如果您使用的是Rails 3.2，则可以使用pluck方法仅提取内容

<%= project.tags.pluck(:content).join(",") %>