jQuery.form_params.js

;(function($){
	$.fn.extend({
		/**
		 * @parent dom
		 * @download http://jmvcsite.heroku.com/pluginify?plugins[]=jquery/dom/form_params/form_params.js
		 * @plugin jquery/dom/form_params
		 * @test jquery/dom/form_params/qunit.html
		 * 
		 * Returns an object of name-value pairs that represents values in a form.  
		 * It is able to nest values whose element's name has square brackets.
		 * 
		 * When convert is set to true strings that represent numbers and booleans will
		 * be converted and empty string will not be added to the object. 
		 * 
		 * Example html:
		 * @codestart html
		 * <form>
		 *   <input name="foo[bar]" value='2'/>
		 *   <input name="foo[ced]" value='4'/>
		 * </form>
		 * @codeend
		 * Example code:
		 * 
		 *     $('form').formParams() //-> { foo:{bar:'2', ced: '4'} }
		 * 
		 * 
		 * @demo jquery/dom/form_params/form_params.html
		 * 
		 * @param {Object} [params] If an object is passed, the form will be repopulated
		 * with the values of the object based on the name of the inputs within
		 * the form
		 * @param {Boolean} [convert=false] True if strings that look like numbers 
		 * and booleans should be converted and if empty string should not be added 
		 * to the result. Defaults to false.
		 * @return {Object} An object of name-value pairs.
		 */
		formParams: function( params ) {
			var convert;
			var keyBreaker = /[^\[\]]+/g;

			// Quick way to determine if something is a boolean
			if ( !! params === params ) {
				convert = params;
				params = null;
			}

			return params ? setParams( params ) : getParams( convert );

			function setParams( params ) {
				// Find all the inputs
				this.find("[name]").each(function() {
					var name = $(this).attr("name");
					var parts = name.match( keyBreaker );
					var value;
					for (var i = 0; i < parts.length; i++) {
						value = typeof value === 'object' ? value[parts[i]] : params[parts[i]];
					};

					var $this;

					// Don't do all this work if there's no value
					if ( value !== undefined ) {
						$this = $(this);

						// Nested these if statements for performance
						if ( $this.is(":radio") ) {
							if ( $this.val() == value ) {
								$this.attr("checked", true);
							}
						} else if ( $this.is(":checkbox") ) {
							// Convert single value to an array to reduce
							// complexity
							value = $.isArray( value ) ? value : [value];
							if ( $.inArray( $this.val(), value ) > -1) {
								$this.attr("checked", true);
							}
						} else {
							$this.val( value );
						}
					}
				});
				return this;
			}

			function getParams( convert ) {
				var convertValue = function( value ) {
						if ( $.isNumeric( value )) {
							return parseFloat( value );
						} else if ( value === 'true') {
							return true;
						} else if ( value === 'false' ) {
							return false;
						} else if ( value === '' ) {
							return undefined;
						}
						return value;
					},
					nestData = function( elem, type, data, parts, value, seen ) {
						var name = parts.shift();

						if ( parts.length ) {
							if ( ! data[ name ] ) {
								data[ name ] = {};
							}
							// Recursive call
							nestData( elem, type, data[ name ], parts, value, seen );
						} else {

							// Handle same name case, as well as "last checkbox checked"
							// case
							if ( name in seen && type != "radio" && ! $.isArray( data[ name ] )) {
								if ( name in data ) {
									data[ name ] = [ data[name] ];
								} else {
									data[ name ] = [];
								}
							} else {
								seen[ name ] = true;
							}

							// Finally, assign data
							if ( ( type == "radio" || type == "checkbox" ) && ! elem.is(":checked") ) {
								return
							}

							if ( ! data[ name ] ) {
								data[ name ] = value;
							} else {
								data[ name ].push( value );
							}
						}
					};
				var data = {},
					// This is used to keep track of the checkbox names that we've
					// already seen, so we know that we should return an array if
					// we see it multiple times. Fixes last checkbox checked bug.
					seen = {},
					current;


				this.find("[name]").each(function() {
					var $this    = $(this),
						type     = $this.attr("type"),
						name     = $this.attr("name"),
						value    = $this.val(),
						parts;

					// Don't accumulate submit buttons and nameless elements
					if ( type == "submit" || ! name ) {
						return;
					}

					// Figure out name parts
					parts = name.match( keyBreaker );
					if ( ! parts.length ) {
						parts = [name];
					}

					// Convert the value
					if ( convert ) {
						value = convertValue( value );
					}

					// Assign data recursively
					nestData( $this, type, data, parts, value, seen );

				});

				return data;
			}

		}
	});
})(jQuery);