Question

I’m creating a custom controller generator that derives from Rails::Generators::NamedBase that creates both a controller and views given a particular model name (e.g. Person). I also want to create a _form.html.haml partial that builds a form based on the model’s attributes (I’m using simple_form btw).

What I have so far is:

<% attributes = file_name.capitalize.constantize.columns.map { |c| [Rails::Generator::GeneratedAttribute.new(c.name, c.type)]} %>
- simple_form_for [:admin,@<%=file_name%>] do |f|
  = render 'shared/error_summary', :object => f.object
  .inputs
  <%- attributes.each do |attribute| -%>
    = f.<%= attribute.reference? ? :association : :input %> :<%= attribute.name %>
  <%- end -%>  
  .actions
    = f.button :submit

I’m getting an “uninitialized constant Rails::Generator (NameError)” exception. Not sure what I need to require or if my approach above is even right.

Any help would be awesome.

Thanks -wg

Answer 1

I suspect the problem is that you are missing an s after Generator. The correct method call is:

Rails::Generators::GeneratedAttribute.new

Instead of creating your attributes variable inside your template, it is better to create it inside your generator class in the initialize method. This method looks like this as a skeleton:

  def initialize(*args, &block)
    super

    # Call Rails::Generators::GeneratedAttribute.new here

  end

If you are getting your user to pass in the desired attributes in the form column_name:column_type then you can do the following:

class FooGenerator < Rails::Generators::NamedBase
  argument :model_attributes, type: :array, default: [], banner: "model:attributes"

  def initialize(*args, &block)
    super

    @attributes = []

    model_attributes.each do |attribute|
      @attributes << Rails::Generators::GeneratedAttribute.new(*attribute.split(":")) if attribute.include?(":")
    end
  end
end

You might want to also handle the possibility that no attributes are passed in somehow. This will depend on your needs however so I can’t guide you on that without more information. Sorry!

A good model standard to follow is the nifty_generators source.