Deep Dive into Nested Forms- Overview

Deep Dive into Nested Forms- Overview

In this video lecture, we take a detailed tour through the process of building nested forms: building the form itself using HTML and Rails helper methods, structuring our params hash in a way that makes sense, and ensuring that there are writer methods on our models that receive the data from the params hash—via the controller—and instantiate objects with that data

Objectives

• Describe forms, params, and writer methods as a game of catch

• Use form_for to have Rails generate HTML for us

• Understand what an ActionView::Helpers::FormBuilder object is and what it “knows” about

• Call #local_methods on a FormBuilder object to see all of the methods that are available to it

• Understand that every key in the params hash should correspond to a writer method

• Know what functionality we get for “free” from our association macros, and what functionality we will need to build out ourselves (with custom writers)

• Recognize that the convention is #something_attributes= because there will already be a writer method for #something=, and we don’t want to overwrite that

• Practice building forms in HTML before using the Rails helpers, so that you can be really specific about what exactly you are creating

• Understand that the accepts_nested_attributes_for macro also generates a custom writer, but is much less extensible than building that custom writer yourself

• Instantiate objects in the controller so that fields_for inputs will show up in the view

• Set attributes on objects instantiated in the controller so that the form can introspect on those objects’ attributes and dynamically set labels

Video

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