Module | ActionView::Helpers::FormOptionsHelper
In: | lib/action_view/helpers/form_options_helper.rb

Provides a number of methods for turning different kinds of containers into a set of option tags.

## Options

The `collection_select`, `country_select`, `select`, and `time_zone_select` methods take an `options` parameter, a hash.

- `:include_blank` - set to true or a prompt string if the first option element of the select element is a blank. Useful if there is not a default value required for the select element.

For example,

      select("post", "category", Post::CATEGORIES, {:include_blank => true})

could become:

      <select name="post[category]">
        <option></option>
        <option>joke</option>
        <option>poem</option>
      </select>

Another common case is a select tag for an `belongs_to`-associated object.

Example with @post.person_id => 2:

      select("post", "person_id", Person.find(:all).collect {|p| [ p.name, p.id ] }, {:include_blank => 'None'})

could become:

      <select name="post[person_id]">
        <option value="">None</option>
        <option value="1">David</option>
        <option value="2" selected="selected">Sam</option>
        <option value="3">Tobias</option>
      </select>

- `: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.

Example:

      select("post", "person_id", Person.find(:all).collect {|p| [ p.name, p.id ] }, {:prompt => 'Select Person'})

could become:

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

Like the other form helpers, `select` can accept an `:index` option to manually set the ID used in the resulting output. Unlike other helpers, `select` expects this option to be in the `html_options` parameter.

Example:

      select("album[]", "genre", %w[rap rock country], {}, { :index => nil })

becomes:

      <select name="album[][genre]" id="album__genre">
        <option value="rap">rap</option>
        <option value="rock">rock</option>
        <option value="country">country</option>
      </select>

### Methods

collection_select option_groups_from_collection_for_select options_for_select options_from_collection_for_select select time_zone_options_for_select time_zone_select

### Included Modules

ERB::Util

### Public Instance methods

collection_select(object, method, collection, value_method, text_method, options = {}, html_options = {})

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.find(: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>

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 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.

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.

options_for_select(container, selected = nil)

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>

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

options_from_collection_for_select(collection, value_method, text_method, selected = nil)

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. If `selected` is specified, the element returning a match on `value_method` will get the selected option tag.

Example (call, result). Imagine a loop iterating over each `person` in `@project.people` to generate an input tag:

      options_from_collection_for_select(@project.people, "id", "name")
        <option value="#{person.id}">#{person.name}</option>

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

select(object, method, choices, options = {}, html_options = {})

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.find(: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.

time_zone_options_for_select(selected = nil, priority_zones = nil, model = ::ActiveSupport::TimeZone)

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.

time_zone_select(object, method, priority_zones = nil, options = {}, html_options = {})

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)

[Validate]