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Diffstat (limited to 'guides/source/form_helpers.md')
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1 files changed, 51 insertions, 30 deletions
diff --git a/guides/source/form_helpers.md b/guides/source/form_helpers.md index b8681d493a..4b6d8a93f0 100644 --- a/guides/source/form_helpers.md +++ b/guides/source/form_helpers.md @@ -67,7 +67,7 @@ To create this form you will use `form_tag`, `label_tag`, `text_field_tag`, and This will generate the following HTML: ```html -<form accept-charset="UTF-8" action="/search" method="get"> +<form accept-charset="UTF-8" action="/search" method="get"><div style="margin:0;padding:0;display:inline"><input name="utf8" type="hidden" value="✓" /></div> <label for="q">Search for:</label> <input id="q" name="q" type="text" /> <input name="commit" type="submit" value="Search" /> @@ -221,7 +221,7 @@ Upon form submission the value entered by the user will be stored in `params[:pe WARNING: You must pass the name of an instance variable, i.e. `:person` or `"person"`, not an actual instance of your model object. -Rails provides helpers for displaying the validation errors associated with a model object. These are covered in detail by the [Active Record Validations and Callbacks](./active_record_validations_callbacks.html#displaying-validation-errors-in-the-view) guide. +Rails provides helpers for displaying the validation errors associated with a model object. These are covered in detail by the [Active Record Validations](./active_record_validations.html#displaying-validation-errors-in-views) guide. ### Binding a Form to an Object @@ -290,7 +290,7 @@ The object yielded by `fields_for` is a form builder like the one yielded by `fo ### Relying on Record Identification -The Article model is directly available to users of the application, so — following the best practices for developing with Rails — you should declare it **a resource**: +The Article model is directly available to users of the application, so - following the best practices for developing with Rails - you should declare it **a resource**: ```ruby resources :articles @@ -381,7 +381,7 @@ Here you have a list of cities whose names are presented to the user. Internally ### The Select and Option Tags -The most generic helper is `select_tag`, which — as the name implies — simply generates the `SELECT` tag that encapsulates an options string: +The most generic helper is `select_tag`, which - as the name implies - simply generates the `SELECT` tag that encapsulates an options string: ```erb <%= select_tag(:city_id, '<option value="1">Lisbon</option>...') %> @@ -421,9 +421,9 @@ output: Whenever Rails sees that the internal value of an option being generated matches this value, it will add the `selected` attribute to that option. -TIP: The second argument to `options_for_select` must be exactly equal to the desired internal value. In particular if the value is the integer 2 you cannot pass "2" to `options_for_select` — you must pass 2. Be aware of values extracted from the `params` hash as they are all strings. +TIP: The second argument to `options_for_select` must be exactly equal to the desired internal value. In particular if the value is the integer 2 you cannot pass "2" to `options_for_select` - you must pass 2. Be aware of values extracted from the `params` hash as they are all strings. -WARNING: when `:inlude_blank` or `:prompt:` are not present, `:include_blank` is forced true if the select attribute `required` is true, display `size` is one and `multiple` is not true. +WARNING: when `:include_blank` or `:prompt` are not present, `:include_blank` is forced true if the select attribute `required` is true, display `size` is one and `multiple` is not true. You can add arbitrary attributes to the options using hashes: @@ -451,7 +451,7 @@ In most cases form controls will be tied to a specific database model and as you <%= select(:person, :city_id, [['Lisbon', 1], ['Madrid', 2], ...]) %> ``` -Notice that the third parameter, the options array, is the same kind of argument you pass to `options_for_select`. One advantage here is that you don't have to worry about pre-selecting the correct city if the user already has one — Rails will do this for you by reading from the `@person.city_id` attribute. +Notice that the third parameter, the options array, is the same kind of argument you pass to `options_for_select`. One advantage here is that you don't have to worry about pre-selecting the correct city if the user already has one - Rails will do this for you by reading from the `@person.city_id` attribute. As with other helpers, if you were to use the `select` helper on a form builder scoped to the `@person` object, the syntax would be: @@ -553,7 +553,7 @@ outputs (with actual option values omitted for brevity) which results in a `params` hash like ```ruby -{:person => {'birth_date(1i)' => '2008', 'birth_date(2i)' => '11', 'birth_date(3i)' => '22'}} +{'person' => {'birth_date(1i)' => '2008', 'birth_date(2i)' => '11', 'birth_date(3i)' => '22'}} ``` When this is passed to `Person.new` (or `update`), Active Record spots that these parameters should all be used to construct the `birth_date` attribute and uses the suffixed information to determine in which order it should pass these parameters to functions such as `Date.civil`. @@ -568,7 +568,7 @@ NOTE: In many cases the built-in date pickers are clumsy as they do not aid the ### Individual Components -Occasionally you need to display just a single date component such as a year or a month. Rails provides a series of helpers for this, one for each component `select_year`, `select_month`, `select_day`, `select_hour`, `select_minute`, `select_second`. These helpers are fairly straightforward. By default they will generate an input field named after the time component (for example "year" for `select_year`, "month" for `select_month` etc.) although this can be overridden with the `:field_name` option. The `:prefix` option works in the same way that it does for `select_date` and `select_time` and has the same default value. +Occasionally you need to display just a single date component such as a year or a month. Rails provides a series of helpers for this, one for each component `select_year`, `select_month`, `select_day`, `select_hour`, `select_minute`, `select_second`. These helpers are fairly straightforward. By default they will generate an input field named after the time component (for example "year" for `select_year`, "month" for `select_month` etc.) although this can be overridden with the `:field_name` option. The `:prefix` option works in the same way that it does for `select_date` and `select_time` and has the same default value. The first parameter specifies which value should be selected and can either be an instance of a Date, Time or DateTime, in which case the relevant component will be extracted, or a numerical value. For example @@ -605,7 +605,7 @@ The object in the `params` hash is an instance of a subclass of IO. Depending on ```ruby def upload uploaded_io = params[:person][:picture] - File.open(Rails.root.join('public', 'uploads', uploaded_io.original_filename), 'w') do |file| + File.open(Rails.root.join('public', 'uploads', uploaded_io.original_filename), 'wb') do |file| file.write(uploaded_io.read) end end @@ -664,7 +664,7 @@ Understanding Parameter Naming Conventions As you've seen in the previous sections, values from forms can be at the top level of the `params` hash or nested in another hash. For example in a standard `create` action for a Person model, `params[:person]` would usually be a hash of all the attributes for the person to create. The `params` hash can also contain arrays, arrays of hashes and so on. -Fundamentally HTML forms don't know about any sort of structured data, all they generate is name–value pairs, where pairs are just plain strings. The arrays and hashes you see in your application are the result of some parameter naming conventions that Rails uses. +Fundamentally HTML forms don't know about any sort of structured data, all they generate is name-value pairs, where pairs are just plain strings. The arrays and hashes you see in your application are the result of some parameter naming conventions that Rails uses. TIP: You may find you can try out examples in this section faster by using the console to directly invoke Racks' parameter parser. For example, @@ -830,23 +830,20 @@ Many apps grow beyond simple forms editing a single object. For example when cre ### Configuring the Model -Active Record provides model level support via the `accepts_nested_attributes_for` method: +Active Record provides model level support via the `accepts_nested_attributes_for` method: ```ruby class Person < ActiveRecord::Base has_many :addresses accepts_nested_attributes_for :addresses - - attr_accessible :name, :addresses_attributes end class Address < ActiveRecord::Base belongs_to :person - attr_accessible :kind, :street end ``` -This creates an `addresses_attributes=` method on `Person` that allows you to create, update and (optionally) destroy addresses. When using `attr_accessible` or `attr_protected` you must mark `addresses_attributes` as accessible as well as the other attributes of `Person` and `Address` that should be mass assigned. +This creates an `addresses_attributes=` method on `Person` that allows you to create, update and (optionally) destroy addresses. ### Building the Form @@ -884,19 +881,19 @@ end ```ruby { - :person => { - :name => 'John Doe', - :addresses_attributes => { - '0' => { - :kind => 'Home', - :street => '221b Baker Street', - }, - '1' => { - :kind => 'Office', - :street => '31 Spooner Street' - } - } + 'person' => { + 'name' => 'John Doe', + 'addresses_attributes' => { + '0' => { + 'kind' => 'Home', + 'street' => '221b Baker Street' + }, + '1' => { + 'kind' => 'Office', + 'street' => '31 Spooner Street' + } } + } } ``` @@ -906,7 +903,21 @@ If the associated object is already saved, `fields_for` autogenerates a hidden i ### The Controller -You do not need to write any specific controller code to use nested attributes. Create and update records as you would with a simple form. +As usual you need to +[whitelist the parameters](action_controller_overview.html#strong-parameters) in +the controller before you pass them to the model: + +```ruby +def create + @person = Person.new(person_params) + # ... +end + +private + def person_params + params.require(:person).permit(:name, addresses_attributes: [:id, :kind, :street]) + end +``` ### Removing Objects @@ -937,6 +948,16 @@ If the hash of attributes for an object contains the key `_destroy` with a value <% end %> ``` +Don't forget to update the whitelisted params in your controller to also include +the `_destroy` field: + +```ruby +def person_params + params.require(:person). + permit(:name, addresses_attributes: [:id, :kind, :street, :_destroy]) +end +``` + ### Preventing Empty Records It is often useful to ignore sets of fields that the user has not filled in. You can control this by passing a `:reject_if` proc to `accepts_nested_attributes_for`. This proc will be called with each hash of attributes submitted by the form. If the proc returns `false` then Active Record will not build an associated object for that hash. The example below only tries to build an address if the `kind` attribute is set. @@ -952,4 +973,4 @@ As a convenience you can instead pass the symbol `:all_blank` which will create ### Adding Fields on the Fly -Rather than rendering multiple sets of fields ahead of time you may wish to add them only when a user clicks on an 'Add new child' button. Rails does not provide any builtin support for this. When generating new sets of fields you must ensure the the key of the associated array is unique - the current javascript date (milliseconds after the epoch) is a common choice. +Rather than rendering multiple sets of fields ahead of time you may wish to add them only when a user clicks on an 'Add new address' button. Rails does not provide any builtin support for this. When generating new sets of fields you must ensure the key of the associated array is unique - the current JavaScript date (milliseconds after the epoch) is a common choice. |