In many applications you have some kind of belongs-to or many-to-many associations.
Like a blog post which has many categories, and each category has many blog posts.

It is straightforward to figure out how to make a <.input type="select"> for an Enum,
such as

<.input
          field={@form[:status]}
          type="select"
          label="Status"
          options={Ecto.Enum.values(Post, :status)}
/>

The same approach fails when trying to add a similar dropdown field to select the categories

<.input
          field={@form[:categories]}
          type="select"
          label="Categories"
          options={get_categories()}
/>

with ** (Protocol.UndefinedError) protocol Phoenix.HTML.Safe not implemented for %Category{...

Since this is a common pattern, I would suggest to add some paragraph into guides/client/form-bindings.md to explain the prefered way to solve this.