Associations basics

Select/Multiselect widget

Ordered associations

For has_many/has_and_belongs_to_many/has_many :through

Orderable can be enabled on filtering multiselect fields, allowing selected options to be moved up/down.

RailsAdmin will handle ordering in and out of the form.

RailsAdmin.config do |config|
  config.model Player do
    edit do
      field :fans do
        orderable true
      end
    end
  end
end

You'll need to handle ordering in your model with a position column for example. See here for a comprehensive ActiveRecord example with a has_many :through association.

Important

You must specify attr_accessible for the singular-form _ids setter method of your associated model, e.g., a has_one association. This setter method comes automatically with ActiveRecord when you create a has_many association, but not for a has_one association.

For Rails 3, in the example above you would specify this at the top of your model:

attr_accessible :fan_ids

For Rails 4 and above you need to define setters and getters for has_one associations.

If you fail to do this, the multiselect widget will simply not appear on your page.

Editing records

You can edit related objects by double-clicking on any visible item in the widget.

Querying and searching by association columns

You can configure which columns from associated records show up as available filters or get searched in the general search box. See List#fields-searching for more details.

Limit/filter associated records

See associations scoping for more informations on how to limit and filter proposed associated records.

Inverse_of: Avoiding edit association spaghetti issues

If you set the :inverse_of option on your relations, RailsAdmin will automatically populate the inverse relationship in the modal creation window. (link next to :belongs_to and :has_many multiselect widgets)

It will also hide the inverse relation on nested forms. As a good practice, you should always set :inverse_of options to all your associations, even if these are useless to ActiveRecord (in combination with :through and :as). RailsAdmin will take advantage of them. But it will bomb 'Unknown key: inverse_of' on HABTMs, you'll need to set them manually:

Simply set it directly into your configuration:

config.model Team do
  field :categories do
    inverse_of :teams
  end
end

Readonly

:readonly options are automatically inferred from associations and won't be editable in forms.

Nested form

If you have accepts_nested_attributes_for set up in your model but don't want the association to be a nested form in your model:

config.model Team do
  field :players do
    nested_form false
  end
end

More here

Disabling inline creation and edition

In some cases you may want to disable the addition or edition of an association, the simplest way to do so is by using the inline_add and inline_edit options:

config.model Player do
  field :team do
    inline_add false
    inline_edit false
  end
end

Eager load

Associations can be configured to be eager-loaded to prevent N+1 queries. belongs_to associations are eager-loaded by default, but you can configure additional eager-loads like:

config.model Team do
  field :players do
    eager_load true
  end
end

or passing a custom value:

config.model Team do
  field :players do
    eager_load players: :draft
  end
end