Ecto custom type in Phoenix Form?

Question

I'm using an Ecto custom type in one of my Phoenix application's schemas, like described here (specifically, making use of Postgres Ranges to specify a range of times, like "between 12:00-4:00"). I'm able to insert/retrieve from the database without a problem, but I'm having trouble coming up with a good way to present a form for the user using changesets and Phoenix forms.

So with a schema looks like this (TimeRange is the custom type):

  @primary_key false
  @foreign_key_type :binary_id
  schema "person_messaging_settings" do
    field :can_receive_email, :boolean, null: false
    field :can_receive_sms, :boolean, null: false
    field :allowed_hours, MyApp.Ecto.TimeRange
    belongs_to :person, Person
    timestamps()
  end

I can use inputs_for for the belongs_to association, and ideally I could do something like this in my EEX template:

<%= form_for @changeset, Routes.settings_path(@conn, :update), fn f -> %>

  <!-- other field values -->

  <%= inputs_for f, :allowed_hours, fn ah -> %>
    <%= time_select ah, :upper %>
    <%= time_select ah, :lower %>
  <% end %>
<% end %>

But this complains because inputs_for is strictly for associations.

zwippie zwippie · Accepted Answer · 2019-03-16T01:17:11

Here's a raw untested idea with virtual fields.

Schema file:

schema "person_messaging_settings" do
  # ...
  field :allowed_hours_from, :time, virtual: true
  field :allowed_hours_to, :time, virtual: true
end

def changeset do
  record
  |> cast(attrs, [..., :allowed_hours_from, :allowed_hours_to])
  |> set_allowed_hours()
  |> validate_required([..., :allowed_hours])
end

defp set_allowed_hours(changeset) do
  case {get_field(changeset, :allowed_hours_from), get_field(changeset, :allowed_hours_to)} do
    {nil, nil} -> changeset
    {nil, _}   -> changeset
    {_, nil}   -> changeset
    {from, to} -> put_change(changeset, :allowed_hours, "#{from}-#{to}")
  end
end

And the form:

<%= form_for @changeset, Routes.settings_path(@conn, :update), fn f -> %>

  <!-- other field values -->

  <%= time_select f, :allowed_hours_from %>
  <%= time_select f, :allowed_hours_to %>
<% end %>

Although I don't know how you would populate the two time_selects when editing a saved timerange (decomposing the :allowed_hours). Perhaps somebody else does. Or you render a regular html input with the correct name and value.

Edit 3... Or would this work?

<%= time_select f, :allowed_hours_from, value: something(f.data.allowed_hours) %>

Ecto custom type in Phoenix Form?

1 Answers