Allow to add metadata to an event

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mobilizon/events/event_metadata.ex

@@ -0,0 +1,45 @@
+defmodule Mobilizon.Events.EventMetadata do
+  @moduledoc """
+  Participation stats on event
+  """
+
+  use Ecto.Schema
+  import Ecto.Changeset
+  import EctoEnum
+
+  defenum(EventMetadataTypeEnum, string: 0, integer: 1, boolean: 2)
+
+  @type t :: %__MODULE__{
+          key: String.t(),
+          value: String.t()
+        }
+
+  @required_attrs [
+    :key,
+    :value
+  ]
+
+  @optional_attrs [
+    :title,
+    :type
+  ]
+
+  @attrs @required_attrs ++ @optional_attrs
+
+  @primary_key false
+  @derive Jason.Encoder
+  embedded_schema do
+    field(:key, :string)
+    field(:title, :string)
+    field(:value, :string)
+    field(:type, EventMetadataTypeEnum, default: :string)
+  end
+
+  @doc false
+  @spec changeset(t, map) :: Ecto.Changeset.t()
+  def changeset(%__MODULE__{} = event_metadata, attrs) do
+    event_metadata
+    |> cast(attrs, @attrs)
+    |> validate_required(@required_attrs)
+  end
+end