How to always pre-populate nested form attributes with the Reform gem?

Question

I have a Financing model with has_many: :professional_investments.

To edit the Financing, the main form has a nested form for the professional_investments.

I decided to display a fixed list of 8 professional_investments for now, as the Cocoon gem does not play well with Trailblazer's Reform.

I use two Reform form objects: a FinancingForm, and a nested ProfessionalInvestmentForm:

class FinancingForm < Reform::Form
  collection :professional_investments,
    form: ProfessionalInvestmentForm,
    prepopulator: :prepopulate_professional_investments,
    populate_if_empty: :populate_professional_investments!,
    skip_if: :professional_investment_blank?

  def prepopulate_professional_investments(options)
    [8 - professional_investments.size, 0].max.times do
      professional_investments << ProfessionalInvestment.new
    end
  end

  def populate_professional_investments!(fragment:, **)
    ProfessionalInvestment.new unless professional_investment_blank?(fragment: fragment)
  end

  def professional_investment_blank?(fragment:, **)
    fragment['professional_investor_id'].blank? && fragment['amount'].to_d.zero?
  end
end

In the controller, I create the form object, and pre-populate it:

class FinancingsController < ApplicationController
  def edit
    @financing_form = FinancingForm.new(@financing)
    @financing_form.prepopulate!
  end

  def update
    @financing_form = FinancingForm.new(@financing)
    @financing_form.prepopulate!
    if @financing_form.validate(financing_params)
      @financing_form.save
    end
  end
end

It works, except that blank ProfessionalInvestment are saved as well in the collection, as if the skip_if: parameter had no effect.

If I don't call @financing_form.prepopulate! in update, the blank records are not saved, as intended. But then, if there are validation errors, only the existing records are displayed, not the full pre-populated 8 items list.

How to prevent these blank records from being saved, while still displaying the whole pre-populated nested list in the update action?

How to always pre-populate nested form attributes with the Reform gem?

0 Answers0