How to create a nested form for a has_many through association using simple_form and nested form?

Question

I have a rails app that has an album and song model with a has many through relationship. I'm trying to add songs to albums using the simple_form and nested_form gems. If I use simple_form, it's easy to create the association, but I'm having trouble getting it to work with nested_form. It seems that this should work: ``` <%= f.fields_for :songs do |song_form| %> <%= song_form.association :songs %> <%= song_form.link_to_remove "Remove this song" %> <% end %>

<%= f.link_to_add "Add a song", :songs %>

``` But I get this error: `RuntimeError in Albums#new Association :songs not found`. The association works fine if I just use simple_form. What would the correct syntax be? Or are these gems incompatible? If the two gems are not compatible, then how would you add and remove songs from albums using just nested_form? /views/albums/_form https://gist.github.com/leemcalilly/51e7c5c7e6c4788ad000 /models/album https://gist.github.com/leemcalilly/9a16f43106c788ab6877 /models/song https://gi…

Accepted Answer

The form builder `song_form` represents a `Song` object, not an `Album`, this is why the association is not found. In the block following `fields_for`, you can manually create the form for a song. And like @david mentioned in his comment, you should use `simple_fields_for` instead of `fields_for` to get all simple_form methods available. Which results in: ``` <%= f.simple_fields_for :songs do |song_form| %> <%= song_form.input :artwork %> <%= song_form.input :track %> ... <%= song_form.link_to_remove "Remove this song" %> <% end %> ```

How to create a nested form for a has_many through association using simple_form and nested form?

Solution

Problem