Rails nested attributes with no creation if nested attributes are blank

Question

I have a nested attributes between:

class InventoryItem < ApplicationRecord
  belongs_to :location
  accepts_nested_attributes_for :location
end

class Location < ApplicationRecord
  has_many :inventory_items
  has_many :bins
  accepts_nested_attributes_for :bins
end

class Bin < ApplicationRecord
  belongs_to :location
end

The inventory_item form:

  <%= form.fields_for :location do |location| %>
    <div class="field">
      <%= location.label :location_name %>
      <%= location.text_field :name %>
    </div>
      <%= location.fields_for :bins do |bin| %>
        <div class="field">
          <%= bin.label :bin_name %>
          <%= bin.text_field :name %>
      </div>
      <% end %>
    </div>
  <% end %>

And in the inventory_item controller:

  def new
    @inventory_item = InventoryItem.new
    @inventory_item.build_location.bins.build
  end

  def inventory_item_params
    params.require(:inventory_item).permit(:location_id, location_attributes:[:name, bins_attributes:[:name]])
  end

The form:

My issue is that I can create an InventoryItem with a Location and Bin name blank and it creates a new Location and Bin and the corresponding association between InventoryItem and a blank Location. I want that when Location name or Bin name are blank in the form a new Location, a new Bin and the association will not be created.

Thanks in advance

Deepesh · Accepted Answer · 2021-07-16 11:53:50Z

2

You can add a validation like this:

accepts_nested_attributes_for :location, reject_if: proc { |l| l[:name].blank? }

or you can also create a method in the InventoryItem model when to reject and call like this:

accepts_nested_attributes_for :location, reject_if: :reject_method?

def reject_method(attributes)
  attributes['name'].blank?
end

Read more about the syntax here: https://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html

answered Jul 16, 2021 at 11:53

Deepesh

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7 Comments

John Fadria Over a year ago

Thanks @deepesh, my problem now is that Location must exist

Deepesh Over a year ago

You can add validates_presence_of :location to check that on the InventoryItem model

John Fadria Over a year ago

Sorry @deepesh with this validation I optain two errors now. Location must exist and Location can't be blank If is blank I want to create the InventoryItem without a Location

Deepesh Over a year ago

Location can't be blank is from the validation we have added above, the must exist is from the belongs_to association.

Deepesh Over a year ago

stackoverflow.com/questions/38983666/…

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