Default value of `attrs` of `Context.update_*`?

Phoenix Forum Questions / Help
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1

I am using mix phx.gen.html, and I noticed following code:

  def create_tag(attrs \\ %{}) do
    %Tag{}
    |> Tag.changeset(attrs)
    |> Repo.insert()
  end

  def update_tag(%Tag{} = tag, attrs) do
    tag
    |> Tag.changeset(attrs)
    |> Repo.update()
  end

  def change_tag(%Tag{} = tag, attrs \\ %{}) do
    Tag.changeset(tag, attrs)
  end

attrs argument of create_tag and change_tag has a default value %{}.

But, attrs argument of update_tag doesn’t. Why doesn’t it have the default value ? Is it removed on purpose?

1 Like
2

Creating an entity without explicit user input it something, which you might want to allow. Your entity/changeset might be able to supply enough defaults for it to be created. But updating without something to update doesn’t really make sense – at least not if your update_* is a “pure” function without pulling changes in via some side-effects.

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