I may be going about this the wrong way but I can’t seem to figure out a good way to handle input for “tags” in a blog post. I’ve looked at using .inputs_for but I don’t want to create an input field for every tag. Ideally, it would just be a single text input that spits the value on spaces and transforms those into “tag” structs. Maybe this would be better to do outside a form?

I’ve been messing with it for hours and this doesn’t seem like it should be that difficult. Hopefully someone can point out an easier way I’m missing. Here is what I have right now (back to square one because the handful of things I tried hadn’t worked).

form_component.ex

#...
  @impl true
  def render(assigns) do
    ~H"""
    <div>
      <.header>
        <%= @title %>
        <:subtitle>by <%= @post.author %></:subtitle>
      </.header>

      <.simple_form
        :let={form}
        for={@form}
        id="post-form"
        as={"post_form"}
        phx-target={@myself}
        phx-change="validate"
        phx-submit="save"
      >
        <.input field={@form[:title]} type="text" label="Title" />
        <.input field={@form[:tags]} type="text" label="Tags"/> # <<<< This doesn't work, of course.
        <.input field={@form[:author]} type="hidden" />
        <.input field={@form[:body]} type="textarea" label="Body" />
        <:actions>
          <.button phx-disable-with="Saving...">Save Post</.button>
        </:actions>
      </.simple_form>
    </div>
    """
  end
# ...

post.ex

defmodule Personal.Blog.Post do
  use Ecto.Schema
  import Ecto.Changeset

  schema "posts" do
    field :author, :string
    field :body, :string
    field :title, :string
    field :views, :integer, default: 0
    many_to_many(:tags, Personal.Blog.Tag, join_through: "post_tags",  on_replace: :delete)

    timestamps(type: :utc_datetime)
  end

  @doc false
  def changeset(post, attrs) do
    post
    |> cast(attrs, [:title, :author, :body, :views])
    |> validate_required([:title, :author, :body, :views])
  end
end

tag.ex

defmodule Personal.Blog.Tag do
  use Ecto.Schema
  import Ecto.Changeset

  schema "tags" do
    field :name, :string, default: ""
    many_to_many(:posts, Personal.Blog.Post, join_through: "post_tags", on_replace: :delete)

    timestamps(type: :utc_datetime)
  end

  @doc false
  def changeset(tag, attrs) do
    tag
    |> cast(attrs, [:name])
    |> validate_required([:name])
  end
end

post_tag.ex

defmodule Personal.Blog.PostTag do
  use Ecto.Schema
  import Ecto.Changeset

  schema "post_tags" do
    belongs_to(:posts, Personal.Blog.Post)
    belongs_to(:tags, Personal.Blog.Tag)

    timestamps(type: :utc_datetime)
  end

  @doc false
  def changeset(post_tag, attrs) do
    post_tag
    |> cast(attrs, [:post_id, :tag_id])
    |> validate_required([:post_id, :tag_id])
  end
end