I found creating search forms in Rails a little awkward because most of the built in Rails form elements expect to work with attributes of an object, whereas for a search form I just needed to pass a set of attributes. The solution was simple – create a temporary object to hold search attributes. <\/p>\n
When I first create the class I now use to solve this issue, I just intended to use it for search forms, but I now find I’m using it for other things such as organising the data returned by custom SQL calls.<\/p>\n
Here is the class definition. I’ll add a couple of other blog entries to describe how I use it.<\/p>\n
\r\n# An object used to store data\r\n# Attributes can be generated both on initiation and later\r\n\r\n# Usage\r\n# t = TempObject.new('one')\r\n# t.one = \"Hi!\"\r\n# puts t.one ---> \"Hi!\"\r\n# t.create_attribute('two')\r\n# t.two = \"Hello again\"\r\n# puts t.two ---> \"Hello again\"\r\nclass TempObject\r\n \r\n def initialize(*attribute_names)\r\n @attribute_names = Array.new\r\n attribute_names.flatten.each do |a| \r\n create_attribute(a)\r\n end\r\n end\r\n \r\n # Creates a new attribute with a name defined by name\r\n # The example below generates two methods: the setter 'two=' and the getter two\r\n #\r\n # t = TempObject.new\r\n # t.create_attribute('two')\r\n # t.two = \"Hello\"\r\n # puts t.two ---> \"Hello\"\r\n def create_attribute(name)\r\n name = name.to_sym\r\n self.class.send(:attr_accessor, name)\r\n @attribute_names << name\r\n end\r\n \r\n # Returns a list of the attributes added to this object\r\n def attribute_names\r\n @attribute_names\r\n end\r\n \r\n # Allows data to be loaded into the attributes from a Hash.\r\n # t = TempObject.new(:one, :two)\r\n # t.load_data({:one => 1, 'two' => 2, :three => 3})\r\n # puts t.one ---> 1\r\n # puts t.three ---> error no method\r\n def load_data(data = nil)\r\n if data\r\n @attribute_names.each do |a|\r\n if value = data[a.to_sym] or value = data[a.to_s]\r\n instance_variable_set(\"@#{a}\", value)\r\n end\r\n end\r\n end\r\n end\r\n \r\n # Allows a new object to be created from a hash in one step\r\n # All data in hash will be used to populate new object\r\n # t = TempObject.new_and_load_all({:one => 1, :two => 2})\r\n # puts t.one ---> 1\r\n def self.new_and_load_all(data)\r\n if data.kind_of?(Hash) and data.length > 0\r\n object = self.new(data.keys)\r\n object.load_data(data)\r\n end\r\n return object\r\n end\r\n\r\n # Takes an array of hashes (for example from a connection.select_all\r\n # and returns an array of TempOjects created from the hashes\r\n def self.create_from_array_of_hashes(array)\r\n array.collect{|hash| TempObject.new_and_load_all(hash)}\r\n end\r\n \r\n def report\r\n report_data = Array.new\r\n for attribute in attribute_names\r\n value = send(attribute)\r\n value = value.strftime(\"%a %d-%b-%y %H:%M\") if value.kind_of? Time\r\n report_data << \"#{attribute.to_s.capitalize} : #{value}\" if value\r\n end\r\n return report_data\r\n end\r\n\r\nend\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"I found creating search forms in Rails a little awkward because most of the built in Rails form elements expect to work with attributes of an object, whereas for a search form I just needed to pass a set of … Continue reading