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 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 specialized to include both a prepend_text and append_text to properly introduce the error and a css_class to style it accordingly. Examples (post has an error message "can’t be empty" on the title attribute):
<%= 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>
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# File vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb, line 85
85: def error_message_on(object, method, prepend_text = "", append_text = "", css_class = "formError")
86: if errors = instance_eval("@#{object}").errors.on(method)
87: "<div class=\"#{css_class}\">#{prepend_text + (errors.is_a?(Array) ? errors.first : errors) + append_text}</div>"
88: end
89: end
Returns a string with a div containing all the error messages for the object located as an instance variable by the name of object_name. This div can be tailored by the following options:
- header_tag - Used for the header of the error div (default: h2)
- id - The id of the error div (default: errorExplanation)
- class - The class of the error div (default: errorExplanation)
[ show source ]
# File vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb, line 97
97: def error_messages_for(object_name, options = {})
98: options = options.symbolize_keys
99: object = instance_eval "@#{object_name}"
100: unless object.errors.empty?
101: content_tag("div",
102: content_tag(
103: options[:header_tag] || "h2",
104: "#{pluralize(object.errors.count, "error")} prohibited this #{object_name.to_s.gsub("_", " ")} from being saved"
105: ) +
106: content_tag("p", "There were problems with the following fields:") +
107: content_tag("ul", object.errors.full_messages.collect { |msg| content_tag("li", msg) }),
108: "id" => options[:id] || "errorExplanation", "class" => options[:class] || "errorExplanation"
109: )
110: end
111: end
Returns an entire form with input tags and everything for a specified Active Record object. Example (post is a new record that has a title using VARCHAR and a body using TEXT):
form("post") =>
<form action='/post/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" wrap="virtual">
Back to the hill and over it again!
</textarea>
</p>
<input 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. Example (entry is a new record that has a message attribute using VARCHAR):
form("entry", :action => "sign", :input_block =>
Proc.new { |record, column| "#{column.human_name}: #{input(record, column.name)}<br />" }) =>
<form action='/post/sign' method='post'>
Message:
<input id="post_title" name="post[title]" size="30" type="text" value="Hello World" /><br />
<input 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
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# File vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb, line 59
59: def form(record_name, options = nil)
60: options = (options || {}).symbolize_keys
61: record = instance_eval("@#{record_name}")
62:
63: options[:action] ||= record.new_record? ? "create" : "update"
64: action = url_for(:action => options[:action])
65:
66: submit_value = options[:submit_value] || options[:action].gsub(/[^\w]/, '').capitalize
67:
68: id_field = record.new_record? ? "" : InstanceTag.new(record_name, "id", self).to_input_field_tag("hidden")
69:
70: formtag = %(<form action="#{action}" method="post">#{id_field}) + all_input_tags(record, record_name, options)
71: yield formtag if block_given?
72: formtag + %(<input type="submit" value="#{submit_value}" /></form>)
73: end
Returns a default input tag for the type of object returned by the method. Example (title is a VARCHAR column and holds "Hello World"):
input("post", "title") =>
<input id="post_title" name="post[title]" size="30" type="text" value="Hello World" />
[ show source ]
# File vendor/rails/actionpack/lib/action_view/helpers/active_record_helper.rb, line 20
20: def input(record_name, method)
21: InstanceTag.new(record_name, method, self).to_tag
22: end