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redirect_from: /docs/3-index-pages/index-as-table.html

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
  selectable_column
  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
  selectable_column
  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
  selectable_column
  column "Title" do |post|
    link_to post.title, admin_post_path(post)
  end
end

Defining Actions

To setup links to View, Edit and Delete a resource, use the actions method:

index do
  selectable_column
  column :title
  actions
end

You can also append custom links to the default links:

index do
  selectable_column
  column :title
  actions do |post|
    item "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|
    item "View", admin_post_path(post)
  end
end

Or append custom action with custom html via arbre:

index do
  column :title
  actions do |post|
    a "View", href: admin_post_path(post)
  end
end

In case you prefer to list actions links in a dropdown menu:

index do
  selectable_column
  column :title
  actions dropdown: true do |post|
    item "Preview", admin_preview_post_path(post)
  end
end

In addition, you can insert the position of the row in the greater collection by using the index_column special command:

index do
  selectable_column
  index_column
  column :title
end

index_column take an optional offset parameter to allow a developer to set the starting number for the index (default is 1).

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.

By default, this is the column on the resource’s table that the attribute corresponds to.
Otherwise, any attribute that the resource collection responds to can be used.

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

It’s also possible to sort by PostgreSQL’s hstore column key. You should set sortable
option to a column->'key' value:

index do
  column :keywords, sortable: "meta->'keywords'"
end

Custom sorting

It is also possible to use database specific expressions and options for sorting by column

order_by(:title) do |order_clause|
   if order_clause.order == 'desc'
     [order_clause.to_sql, 'NULLS LAST'].join(' ')
   else
     [order_clause.to_sql, 'NULLS FIRST'].join(' ')
   end
end

index do
  column :title
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
    super.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
  column :secret_data if can? :manage, Post
end

Custom row class

In order to add special class to table rows pass the proc object as a :row_class option
of the index method.

index row_class: ->elem { 'active' if elem.active? } do
  # columns
end