class Erector::HtmlWidget

A Widget is the center of the Erector universe.

To create a widget, extend Erector::Widget and implement the content method. Inside this method you may call any of the tag methods like span or p to emit HTML/XML tags.

You can also define a widget on the fly by passing a block to new. This block will get executed when the widget’s content method is called. See the userguide for important details about the scope of this block when run –

To render a widget from the outside, instantiate it and call its to_html method.

A widget’s new method optionally accepts an options hash. Entries in this hash are converted to instance variables.

You can add runtime input checking via the needs macro. See needs. This mechanism is meant to ameliorate development-time confusion about exactly what parameters are supported by a given widget, avoiding confusing runtime NilClass errors.

To call one widget from another, inside the parent widget’s content method, instantiate the child widget and call the widget method. This assures that the same output stream is used, which gives better performance than using capture or to_html. It also preserves the indentation and helpers of the enclosing class.

In this documentation we’ve tried to keep the distinction clear between methods that emit text and those that return text. “Emit” means that it writes to the output stream; “return” means that it returns a string like a normal method and leaves it up to the caller to emit that string if it wants.

This class extends AbstractWidget and includes several modules, so be sure to check all of those places for API documentation for the various methods of Widget:

Also read the API Cheatsheet in the user guide at

Public Instance Methods

to_html(options = {}) click to toggle source

alias for AbstractWidget#render

# File lib/erector/html_widget.rb, line 198
def to_html(options = {})
  raise "Erector::Widget#to_html takes an options hash, not a symbol. Try calling \"to_html(:content_method_name=> :#{options})\"" if options.is_a? Symbol
to_s(*args) click to toggle source

alias for to_html @deprecated Please use {to_html} instead

# File lib/erector/html_widget.rb, line 205
def to_s(*args)
  unless defined? @@already_warned_to_s
    $stderr.puts "Erector::Widget#to_s is deprecated. Please use #to_html instead. Called from #{caller.first}"
    @@already_warned_to_s = true