kostonstyle
Hi all
Look at the following code from https://hexdocs.pm/ecto/Ecto.Changeset.html#cast/4 about cast function:
iex> changeset = cast(post, %{title: "Hello"}, [:title])
iex> new_changeset = cast(changeset, %{title: "Foo", body: "Bar"}, [:body])
iex> new_changeset.params
%{"title" => "Foo", "body" => "Bar"}
Why the title is going to changed to Foo? On second line, it tells only the body field is going to be change!
Thanks
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benwilson512
That isn’t what the
[:body]list means. It means "Cast the:bodyparameter into the changeset. If there is already changes casted into the changeset, it’s just added to that. This is covered in the docs you linked:Also Liked
Olshansk
While elixir does let you chain changesets so you can leverage piping, the docs are incorrect.
The second cast specified that :body is the only value that can be updated based on the params provided, so :title will be ignored. This makes sense functionally which leads me to believe that it is a simple typo.
I added a PR for this here: Update changeset.ex by Olshansk · Pull Request #1958 · elixir-ecto/ecto · GitHub