Module | ActionView::Helpers::ActiveRecordHelper |
In: |
vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb
|
The Active Record Helper makes it easier to create forms for records kept in instance variables. The most far-reaching is the form method that creates a complete form for all the basic content types of the record (not associations or aggregations, though). This is a great way of making the record quickly available for editing, but likely to prove lackluster for a complicated real-world form. In that case, it‘s better to use the input method and the specialized form methods in classes/ActionView/Helpers/FormHelper.html
Returns a string containing the error message attached to the method on the object if one exists. This error message is wrapped in a DIV tag, which can be extended to include a prepend_text and/or append_text (to properly explain the error), and a css_class to style it accordingly. object should either be the name of an instance variable or the actual object. As an example, let‘s say you have a model @post that has an error message on the title attribute:
<%= error_message_on "post", "title" %> # => <div class="formError">can't be empty</div> <%= error_message_on @post, "title" %> # => <div class="formError">can't be empty</div> <%= error_message_on "post", "title", "Title simply ", " (or it won't work).", "inputError" %> # => <div class="inputError">Title simply can't be empty (or it won't work).</div>
# File vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb, line 105 105: def error_message_on(object, method, prepend_text = "", append_text = "", css_class = "formError") 106: if (obj = (object.respond_to?(:errors) ? object : instance_variable_get("@#{object}"))) && 107: (errors = obj.errors.on(method)) 108: content_tag("div", "#{prepend_text}#{errors.is_a?(Array) ? errors.first : errors}#{append_text}", :class => css_class) 109: else 110: '' 111: end 112: end
Returns a string with a DIV containing all of the error messages for the objects located as instance variables by the names given. If more than one object is specified, the errors for the objects are displayed in the order that the object names are provided.
This DIV can be tailored by the following options:
To specify the display for one object, you simply provide its name as a parameter. For example, for the @user model:
error_messages_for 'user'
To specify more than one object, you simply list them; optionally, you can add an extra :object_name parameter, which will be the name used in the header message:
error_messages_for 'user_common', 'user', :object_name => 'user'
If the objects cannot be located as instance variables, you can add an extra :object paremeter which gives the actual object (or array of objects to use):
error_messages_for 'user', :object => @question.user
NOTE: This is a pre-packaged presentation of the errors with embedded strings and a certain HTML structure. If what you need is significantly different from the default presentation, it makes plenty of sense to access the object.errors instance yourself and set it up. View the source of this method to see how easy it is.
# File vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb, line 152 152: def error_messages_for(*params) 153: options = params.extract_options!.symbolize_keys 154: if object = options.delete(:object) 155: objects = [object].flatten 156: else 157: objects = params.collect {|object_name| instance_variable_get("@#{object_name}") }.compact 158: end 159: count = objects.inject(0) {|sum, object| sum + object.errors.count } 160: unless count.zero? 161: html = {} 162: [:id, :class].each do |key| 163: if options.include?(key) 164: value = options[key] 165: html[key] = value unless value.blank? 166: else 167: html[key] = 'errorExplanation' 168: end 169: end 170: options[:object_name] ||= params.first 171: options[:header_message] = "#{pluralize(count, 'error')} prohibited this #{options[:object_name].to_s.gsub('_', ' ')} from being saved" unless options.include?(:header_message) 172: options[:message] ||= 'There were problems with the following fields:' unless options.include?(:message) 173: error_messages = objects.sum {|object| object.errors.full_messages.map {|msg| content_tag(:li, msg) } }.join 174: 175: contents = '' 176: contents << content_tag(options[:header_tag] || :h2, options[:header_message]) unless options[:header_message].blank? 177: contents << content_tag(:p, options[:message]) unless options[:message].blank? 178: contents << content_tag(:ul, error_messages) 179: 180: content_tag(:div, contents, html) 181: else 182: '' 183: end 184: end
Returns an entire form with all needed input tags for a specified Active Record object. For example, if @post has attributes named title of type VARCHAR and body of type TEXT then
form("post")
would yield a form like the following (modulus formatting):
<form action='/posts/create' method='post'> <p> <label for="post_title">Title</label><br /> <input id="post_title" name="post[title]" size="30" type="text" value="Hello World" /> </p> <p> <label for="post_body">Body</label><br /> <textarea cols="40" id="post_body" name="post[body]" rows="20"></textarea> </p> <input name="commit" type="submit" value="Create" /> </form>
It‘s possible to specialize the form builder by using a different action name and by supplying another block renderer. For example, if @entry has an attribute message of type VARCHAR then
form("entry", :action => "sign", :input_block => Proc.new { |record, column| "#{column.human_name}: #{input(record, column.name)}<br />" })
would yield a form like the following (modulus formatting):
<form action="/entries/sign" method="post"> Message: <input id="entry_message" name="entry[message]" size="30" type="text" /><br /> <input name="commit" type="submit" value="Sign" /> </form>
It‘s also possible to add additional content to the form by giving it a block, such as:
form("entry", :action => "sign") do |form| form << content_tag("b", "Department") form << collection_select("department", "id", @departments, "id", "name") end
The following options are available:
# File vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb, line 75 75: def form(record_name, options = {}) 76: record = instance_variable_get("@#{record_name}") 77: 78: options = options.symbolize_keys 79: options[:action] ||= record.new_record? ? "create" : "update" 80: action = url_for(:action => options[:action], :id => record) 81: 82: submit_value = options[:submit_value] || options[:action].gsub(/[^\w]/, '').capitalize 83: 84: contents = form_tag({:action => action}, :method =>(options[:method] || 'post'), :enctype => options[:multipart] ? 'multipart/form-data': nil) 85: contents << hidden_field(record_name, :id) unless record.new_record? 86: contents << all_input_tags(record, record_name, options) 87: yield contents if block_given? 88: contents << submit_tag(submit_value) 89: contents << '</form>' 90: end
Returns a default input tag for the type of object returned by the method. For example, if @post has an attribute title mapped to a VARCHAR column that holds "Hello World":
input("post", "title") # => <input id="post_title" name="post[title]" size="30" type="text" value="Hello World" />
# File vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb, line 21 21: def input(record_name, method, options = {}) 22: InstanceTag.new(record_name, method, self).to_tag(options) 23: end