Build_assoc problem

Questions / Help
1

This is my function which i am using to build an association with a tag (which is just a string) and a post.

defp save_to_tag_database(tag, post_id) do
    tag_params = %{tag: tag |> String.trim} 
    post = Repo.get!(Post, post_id)
    changeset = post
    |> build_assoc(:tags)
    |>  Tag.changeset(tag_params)
    |> Repo.insert
end

It ends up saving the tag but not the post_id

My schema is that each tag belongs_to :posts, Project.Post and each post has_many :tags, Project.Tag

My migration file current has table(:tags) :post_id, :integer, it used to be :post_id, references(:posts)

I have been trying to do this for a while now but can’t figure it out.

2

Figured it out thanks to the help of gjaldon!

3

Great! Would you mind sharing, for anyone else who might end up reading this in the future with a similar problem? :slight_smile:

1 Like
4

Essentially what happened was that I didn’t include :post_id in my cast. Ended up making it like cast(params, [:tag, :post_id]). Also my belong_to :posts, Project.Post was wrong. It should be belongs_to :post, Project.Post. All in all I won’t forget these little mistakes anymore!

1 Like
5

Thanks, saved me an hour of work :slight_smile: