CODEWITHSUNDEEP
ruby-on-railsrubyformsactiveadmin
Leo
Leo

Reputation: 2103

How to create a form for new resources joined by has_many relationship in Active Admin

I have a simple situation in my database. Author has_many Books.

With Active Admin I want to give users the ability to add new authors with their new books.

What I have right now looks like this:

ActiveAdmin.register Author do
  menu false

  actions :new, :create

  permit_params :books

  form do |f|
    f.has_many :books, new_record: true do |book|
      books.inputs 'book' do
        book.input :title
      end
    end
  end
end

however, when I go to the new action I'm getting the error 

undefined method new_record? for nil:NilClass

pointing to 

f.has_many :books, new_record: true do |book|

Do I need to override new and initialize new objects? What if I want to add multiple books dynamically? Is there a default solution for such a scenario?

Upvotes: 1

Views: 640

Answers (3)

Rafayet Monon
Rafayet Monon

Reputation: 1179

First you have to tell the Author model to accept attributes of Books. You have to do it in the model/author.rb. Add the line -

 accepts_nested_attributes_for :books, :allow_destroy => true

Then you have permit the params in active admin model the right way to accept books attributes.

books_attributes: [:title]

Then you can add the form like below where activeadmin will dynamically handle creating new object or deleting one.

f.has_many :book do |b|
  b.inputs 'Books' do
    b.input :title
  end
end

Upvotes: 0

Piers C
Piers C

Reputation: 2978

Yes. If you want your form to display inputs for a blank book without the user needing to click 'Add book' (default behavior) then pre-populate a book in new:

controller do
  def new
    build_resource
    resource.books << Book.new
    new!
  end

I'm not sure what you mean by "multiple books dynamically" but the default JavaScript and 'Add' button should handle that.

As commented, you do need accepts_nested_attributes_for :books in the model and extend your permit_params.

Upvotes: 2

Paulo Felipe Souza
Paulo Felipe Souza

Reputation: 386

The first thing I could guess just from what you said is that you need to permite user params as well as books. The database needs to INSERT INTO user the same way needs INSERT INTO books. As Rails is a great framework and says "Convention over configuration", the only way we might give to you an apropriated answer is cheking your repository.

However "new_record?" method is always running when you try to INSERT INTO your database new data. You don't see it because it doesn't show nothing UNTIL you try INSERTING new datas without run another database migration. In newest Rails version the migration is running as rails db:migrate. Old Rails versions use rake db:migrate.

As I said, checking your repo is the best way to give you an appropriated answer. Cheers

Upvotes: -1

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