Returns <select> and <option> tags for the collection of existing return values of method for object‘s class. The value returned from calling method on the instance object will be selected. If calling method returns nil, no selection is made without including :prompt or :include_blank in the options hash.

The :value_method and :text_method parameters are methods to be called on each member of collection. The return values are used as the value attribute and contents of each <option> tag, respectively.

Example object structure for use with this method:

  class Post < ActiveRecord::Base
    belongs_to :author
  end
  class Author < ActiveRecord::Base
    has_many :posts
    def name_with_initial
      "#{first_name.first}. #{last_name}"
    end
  end

Sample usage (selecting the associated Author for an instance of Post, @post):

  collection_select(:post, :author_id, Author.all, :id, :name_with_initial, {:prompt => true})

If @post.author_id is already 1, this would return:

  <select name="post[author_id]">
    <option value="">Please select</option>
    <option value="1" selected="selected">D. Heinemeier Hansson</option>
    <option value="2">D. Thomas</option>
    <option value="3">M. Clark</option>
  </select>

Returns <select>, <optgroup> and <option> tags for the collection of existing return values of method for object‘s class. The value returned from calling method on the instance object will be selected. If calling method returns nil, no selection is made without including :prompt or :include_blank in the options hash.

Parameters:

• object - The instance of the class to be used for the select tag
• method - The attribute of object corresponding to the select tag
• 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 the value 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.

Example object structure for use with this method:

  class Continent < ActiveRecord::Base
    has_many :countries
    # attribs: id, name
  end
  class Country < ActiveRecord::Base
    belongs_to :continent
    # attribs: id, name, continent_id
  end
  class City < ActiveRecord::Base
    belongs_to :country
    # attribs: id, name, country_id
  end

Sample usage:

  grouped_collection_select(:city, :country_id, @continents, :countries, :name, :id, :name)

Possible output:

  <select name="city[country_id]">
    <optgroup label="Africa">
      <option value="1">South Africa</option>
      <option value="3">Somalia</option>
    </optgroup>
    <optgroup label="Europe">
      <option value="7" selected="selected">Denmark</option>
      <option value="2">Ireland</option>
    </optgroup>
  </select>

Returns a string of <option> tags, like options_for_select, but wraps them with <optgroup> tags.

Parameters:

• grouped_options - Accepts a nested array or hash of strings. The first value serves as the <optgroup> label while the second value must be an array of options. The second value can be a nested array of text-value pairs. See options_for_select for more info.

   Ex. ["North America",[["United States","US"],["Canada","CA"]]]
  

• selected_key - A value equal to the value attribute for one of the <option> tags, which will have the selected attribute set. Note: It is possible for this value to match multiple options as you might have the same option in multiple groups. Each will then get selected="selected".
• prompt - set to true or a prompt string. When the select element doesn’t have a value yet, this prepends an option with a generic prompt — "Please select" — or the given prompt string.

Sample usage (Array):

  grouped_options = [
   ['North America',
     [['United States','US'],'Canada']],
   ['Europe',
     ['Denmark','Germany','France']]
  ]
  grouped_options_for_select(grouped_options)

Sample usage (Hash):

  grouped_options = {
   'North America' => [['United States','US], 'Canada'],
   'Europe' => ['Denmark','Germany','France']
  }
  grouped_options_for_select(grouped_options)

Possible output:

  <optgroup label="Europe">
    <option value="Denmark">Denmark</option>
    <option value="Germany">Germany</option>
    <option value="France">France</option>
  </optgroup>
  <optgroup label="North America">
    <option value="US">United States</option>
    <option value="Canada">Canada</option>
  </optgroup>

Note: Only the <optgroup> and <option> tags are returned, so you still have to wrap the output in an appropriate <select> tag.

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 the value 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, name
  end
  class Country < ActiveRecord::Base
    belongs_to :continent
    # attribs: id, name, continent_id
  end

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.

Accepts a container (hash, array, enumerable, your type) and returns a string of option tags. Given a container where the elements respond to first and last (such as a two-element array), the "lasts" serve as option values and the "firsts" as option text. Hashes are turned into this form automatically, so the keys become "firsts" and values become lasts. If selected is specified, the matching "last" or element will get the selected option-tag. selected may also be an array of values to be selected when using a multiple select.

Examples (call, result):

  options_for_select([["Dollar", "$"], ["Kroner", "DKK"]])
    <option value="$">Dollar</option>\n<option value="DKK">Kroner</option>

  options_for_select([ "VISA", "MasterCard" ], "MasterCard")
    <option>VISA</option>\n<option selected="selected">MasterCard</option>

  options_for_select({ "Basic" => "$20", "Plus" => "$40" }, "$40")
    <option value="$20">Basic</option>\n<option value="$40" selected="selected">Plus</option>

  options_for_select([ "VISA", "MasterCard", "Discover" ], ["VISA", "Discover"])
    <option selected="selected">VISA</option>\n<option>MasterCard</option>\n<option selected="selected">Discover</option>

If you wish to specify disabled option tags, set selected to be a hash, with :disabled being either a value or array of values to be disabled. In this case, you can use :selected to specify selected option tags.

Examples:

  options_for_select(["Free", "Basic", "Advanced", "Super Platinum"], :disabled => "Super Platinum")
    <option value="Free">Free</option>\n<option value="Basic">Basic</option>\n<option value="Advanced">Advanced</option>\n<option value="Super Platinum" disabled="disabled">Super Platinum</option>

  options_for_select(["Free", "Basic", "Advanced", "Super Platinum"], :disabled => ["Advanced", "Super Platinum"])
    <option value="Free">Free</option>\n<option value="Basic">Basic</option>\n<option value="Advanced" disabled="disabled">Advanced</option>\n<option value="Super Platinum" disabled="disabled">Super Platinum</option>

  options_for_select(["Free", "Basic", "Advanced", "Super Platinum"], :selected => "Free", :disabled => "Super Platinum")
    <option value="Free" selected="selected">Free</option>\n<option value="Basic">Basic</option>\n<option value="Advanced">Advanced</option>\n<option value="Super Platinum" disabled="disabled">Super Platinum</option>

NOTE: Only the option tags are returned, you have to wrap this call in a regular HTML select tag.

Returns a string of option tags that have been compiled by iterating over the collection and assigning the the result of a call to the value_method as the option value and the text_method as the option text. Example:

  options_from_collection_for_select(@people, 'id', 'name')

This will output the same HTML as if you did this:

  <option value="#{person.id}">#{person.name}</option>

This is more often than not used inside a select_tag like this example:

  select_tag 'person', options_from_collection_for_select(@people, 'id', 'name')

If selected is specified as a value or array of values, the element(s) returning a match on value_method will be selected option tag(s).

If selected is specified as a Proc, those members of the collection that return true for the anonymous function are the selected values.

selected can also be a hash, specifying both :selected and/or :disabled values as required.

Be sure to specify the same class as the value_method when specifying selected or disabled options. Failure to do this will produce undesired results. Example:

  options_from_collection_for_select(@people, 'id', 'name', '1')

Will not select a person with the id of 1 because 1 (an Integer) is not the same as ‘1’ (a string)

  options_from_collection_for_select(@people, 'id', 'name', 1)

should produce the desired results.

Create a select tag and a series of contained option tags for the provided object and method. The option currently held by the object will be selected, provided that the object is available. See options_for_select for the required format of the choices parameter.

Example with @post.person_id => 1:

  select("post", "person_id", Person.all.collect {|p| [ p.name, p.id ] }, { :include_blank => true })

could become:

  <select name="post[person_id]">
    <option value=""></option>
    <option value="1" selected="selected">David</option>
    <option value="2">Sam</option>
    <option value="3">Tobias</option>
  </select>

This can be used to provide a default set of options in the standard way: before rendering the create form, a new model instance is assigned the default options and bound to @model_name. Usually this model is not saved to the database. Instead, a second model object is created when the create request is received. This allows the user to submit a form page more than once with the expected results of creating multiple records. In addition, this allows a single partial to be used to generate form inputs for both edit and create forms.

By default, post.person_id is the selected option. Specify :selected => value to use a different selection or :selected => nil to leave all options unselected. Similarly, you can specify values to be disabled in the option tags by specifying the :disabled option. This can either be a single value or an array of values to be disabled.

Returns a string of option tags for pretty much any time zone in the world. Supply a TimeZone name as selected to have it marked as the selected option tag. You can also supply an array of TimeZone objects as priority_zones, so that they will be listed above the rest of the (long) list. (You can use TimeZone.us_zones as a convenience for obtaining a list of the US time zones, or a Regexp to select the zones of your choice)

The selected parameter must be either nil, or a string that names a TimeZone.

By default, model is the TimeZone constant (which can be obtained in Active Record as a value object). The only requirement is that the model parameter be an object that responds to all, and returns an array of objects that represent time zones.

NOTE: Only the option tags are returned, you have to wrap this call in a regular HTML select tag.

Return select and option tags for the given object and method, using time_zone_options_for_select to generate the list of option tags.

In addition to the :include_blank option documented above, this method also supports a :model option, which defaults to TimeZone. This may be used by users to specify a different time zone model object. (See time_zone_options_for_select for more information.)

You can also supply an array of TimeZone objects as priority_zones, so that they will be listed above the rest of the (long) list. (You can use TimeZone.us_zones as a convenience for obtaining a list of the US time zones, or a Regexp to select the zones of your choice)

Finally, this method supports a :default option, which selects a default TimeZone if the object‘s time zone is nil.

Examples:

  time_zone_select( "user", "time_zone", nil, :include_blank => true)

  time_zone_select( "user", "time_zone", nil, :default => "Pacific Time (US & Canada)" )

  time_zone_select( "user", 'time_zone', TimeZone.us_zones, :default => "Pacific Time (US & Canada)")

  time_zone_select( "user", 'time_zone', [ TimeZone['Alaska'], TimeZone['Hawaii'] ])

  time_zone_select( "user", 'time_zone', /Australia/)

  time_zone_select( "user", "time_zone", TZInfo::Timezone.all.sort, :model => TZInfo::Timezone)