Index as a Table
By default, the index page is a table with each of the models content columns and links to show, edit and delete the object. There are many ways to customize what gets displayed.
Defining Columns
To display an attribute or a method on a resource, simply pass a symbol into the column method:
index do
column :title
end
For association columns we make an educated guess on what to display by calling the following methods in the following order:
:display_name, :full_name, :name, :username, :login, :title, :email, :to_s
This can be customized in config/initializers/active_admin.rb.
If the default title does not work for you, pass it as the first argument:
index do
column "My Custom Title", :title
end
Sometimes that just isn't enough and you need to write some view-specific code. For example, say we wanted a "Title" column that links to the posts admin screen.
column
accepts a block that will be rendered for each of the objects in the collection.
The block is called once for each resource, which is passed as an argument to the block.
index do
column "Title" do |post|
link_to post.title, admin_post_path(post)
end
end
To setup links to View, Edit and Delete a resource, use the actions
method:
index do
column :title
actions
end
You can also append custom links to the default links:
index do
column :title
actions do |post|
link_to "Preview", admin_preview_post_path(post), :class => "member_link"
end
end
Or forego the default links entirely:
index do
column :title
actions :defaults => false do |post|
link_to "View", admin_post_path(post)
end
end
Sorting
When a column is generated from an Active Record attribute, the table is sortable by default. If you are creating a custom column, you may need to give Active Admin a hint for how to sort the table.
If a column is defined using a block, you must pass the key to turn on sorting. The key is the attribute which gets used to sort objects using Active Record.
index do
column "Title", :sortable => :title do |post|
link_to post.title, admin_post_path(post)
end
end
You can turn off sorting on any column by passing false:
index do
column :title, :sortable => false
end
Associated Sorting
You're normally able to sort columns alphabetically, but by default you can't sort by associated objects. Though with a few simple changes, you can.
Assuming you're on the Books index page, and Book has_one Publisher:
controller do
def scoped_collection
resource_class.includes(:publisher) # prevents N+1 queries to your database
end
end
Then it's simple to sort by any Publisher attribute from within the index table:
index do
column :publisher, sortable: 'publishers.name'
end
Showing and Hiding Columns
The entire index block is rendered within the context of the view, so you can easily do things that show or hide columns based on the current context.
For example, if you were using CanCan:
index do
column :title, :sortable => false
if can? :manage, Post
column :some_secret_data
end
end