Setting up to invoke form helpers from Rails console

Question

I'd like to experiment with using form helpers inside the Rails console, but my simple minded approach of doing extend ActionView::Helpers::FormHelper didn't work. For example, subsequently calling form_for resulted in the error NoMethodError: undefined method 'dom_class' for main:Object. Using include produces the same results.

Is there an "easy" way to enable me to call form helpers from the console? I'd prefer to do this without any dependency on controller or view files, if possible.

Answer 1

Peter, I'm happy to solve your problem.

For simple view helpers, it's very easy

> app.helper.link_to 'root', app.root_path
# <a href = ....> # as expected

However your specific case is not that easy as form_for needs view_context and then a controller instance to work.

# Get a controller instance at first. Must do it.
# Without this step `app.controller` is nil
> app.get app.root_path

# Use an instance variable but not variable!
> @user = User.last

# Get the view
# Note you need to take the trouble to define url manually
# because console can only reach path through app instance
> app.controller.view_context.form_for(@user, url: app.user_path(@user)){|f| f.input :name}
# Job done

Answer 2

You need to use include, not extend:

irb(main):007:0> include ActionView::Helpers::FormHelper
=> Object
irb(main):008:0> form_for
ArgumentError: wrong number of arguments (0 for 1)