二级下拉选择框option_groups_from_collection_for_select
class Group < ActiveRecord::Base has_and_belongs_to_many :users # attribs: id, nameendclass User < ActiveRecord::Base has_and_belongs_to_many :groups # attribs: id, nameendclass Delivery < ActiveRecord::Base belongs_to :recipient, :class_name => "User", :foreign_key => :recipient_id # attribs: id, name, recipient_idend?
option_groups_from_collection_for_select(Group.all, :users, :name, :id, :name, @delivery.recipient_id)
?
效果：
金工组-------------------group_name
? ?用户1------------------user_name
铆焊组
? ?用户2
? ?用户3
?
api说明：option_groups_from_collection_for_select(collection, group_method, group_label_method, option_key_method, option_value_method, selected_key = nil)Returns a string of?<option>?tags, like?options_from_collection_for_select, but groups them by?<optgroup>?tags based on the object relationships of the arguments.
Parameters:
collection?- An array of objects representing the?<optgroup>?tags.
group_method?- The name of a method which, when called on a member of?collection, returns an array of child objects representing the?<option>tags.
group_label_method+ - The name of a method which, when called on a member of?collection, returns a string to be used as the?label?attribute for its?<optgroup>?tag.
option_key_method?- The name of a method which, when called on a child object of a member of?collection, returns a value to be used as thevalue?attribute for its?<option>?tag.
option_value_method?- The name of a method which, when called on a child object of a member of?collection, returns a value to be used as the contents of its?<option>?tag.
selected_key?- A value equal to the?value?attribute for one of the?<option>?tags, which will have the?selected?attribute set. Corresponds to the return value of one of the calls to?option_key_method. If?nil, no selection is made. Can also be a hash if disabled values are to be specified.
Example object structure for use with this method:
class Continent < ActiveRecord::Base has_many :countries # attribs: id, nameendclass Country < ActiveRecord::Base belongs_to :continent # attribs: id, name, continent_idend
Sample usage:
option_groups_from_collection_for_select(@continents, :countries, :name, :id, :name, 3)
Possible output:
<optgroup label="Africa"> <option value="1">Egypt</option> <option value="4">Rwanda</option> ...</optgroup><optgroup label="Asia"> <option value="3" selected="selected">China</option> <option value="12">India</option> <option value="5">Japan</option> ...</optgroup>
Note:?Only the?<optgroup>?and?<option>?tags are returned, so you still have to wrap the output in an appropriate?<select>?tag.
