rails fields_for and nested attributes

Question

I have difficulty to understand how to use fields_for and nested attributes. In order to understand it better, I created a repo, which is not working. I read this, which is not helpful. I am using: Rails 4.0.1 Ruby 2.0.0-p247 Question: address form shown, why can not save to database? Why not work? `jack = Person.create(name: 'Jack')` `jack.address.create(street: '12w 33st') ` The main function is as below: ``` #model class Person < ActiveRecord::Base has_one :address accepts_nested_attributes_for :address end class Address < ActiveRecord::Base belongs_to :person end ``` view as below: ``` <%= form_for(@person) do |f| %> <% if @person.errors.any? %>

<%= pluralize(@person.errors.count, "error") %> prohibited this person from being saved:

<%= msg %>

<% end %>

<%= f.label :name %>
<%= f.text_field :name %>

<%= f.lab…

Accepted Answer

Try:

```
jack = Person.create(name: 'Jack')
jack.create_address(street: '12w 33st')
```

When there is only one associated address (`has_one :address`) you use `create_address`. When there are many associated addresses (`has_many :addresses`) you use `addresses.create`.

Also, in your view you will want `f.fields_for` instead of `fields_for`.

I would recommend checking out the RailsCasts for Nested Model Form to learn more.

Additional Info (to address comments below)

Also note that `create` will make a new object and attempt to save it in the database. `build` will just build the new object. In your PeopleController you'll want something like this:

```
def new
  @person = Person.new
  @person.build_address
end
```

Based on your need, you can determine whether you want this `build` to occur in other actions or in callbacks in the model. But this will get you started.

You'll also need to update the `person_params` to

```
def person_params
  params.require(:person).permit(:name, :age, :gender, address_attributes: [:id, :street, :zip_code])
end
```

rails fields_for and nested attributes

Solution

Problem