Fix merging of embed fields

lib/ecto_discriminator/schema.ex

@@ -315,7 +315,7 @@ defmodule EctoDiscriminator.Schema do
       {field_type, meta, [name, existing_type | existing_rest]} ->
         # otherwise in case of conflict and matching types, merge options
         if Macro.expand(type, __ENV__) == Macro.expand(existing_type, __ENV__) do
-          rest = merge_rest_options(existing_rest, List.first(rest) || [])
+          rest = merge_rest_options(existing_rest, rest)
           add_duplicate_meta({field_type, meta, [name, type | rest]})
         else
           new
@@ -349,11 +349,19 @@ defmodule EctoDiscriminator.Schema do
     update_in(ast, [Access.elem(1)], &Keyword.put(&1, :duplicate, true))
   end
 
-  defp merge_rest_options(rest, opts) when is_list(opts) do
+  defp merge_rest_options(rest, opts) do
+    {opts, opts_rest} =
+      case opts do
+        [op | rest] -> {op, rest}
+        op -> {op, []}
+      end
+
+    opts = List.wrap(opts)
+
     case rest do
       [] when opts == [] -> []
       [] -> [opts]
-      [existing] -> [Keyword.merge(existing, opts)]
+      [existing | _] -> [Keyword.merge(existing, opts) | opts_rest]
     end
   end
 

test/ecto_discriminator/discriminator_changeset_test.exs

@@ -30,7 +30,7 @@ defmodule EctoDiscriminator.DiscriminatorChangesetTest do
           source: "asdf",
           is_special: true,
           type: SomeTable.Qux,
-          content: %{length: 7}
+          content: %{text: "abc"}
         })
         |> Ecto.Changeset.apply_action!(:insert)
 

test/ecto_discriminator/schema_test.exs

@@ -437,7 +437,7 @@ defmodule EctoDiscriminator.SchemaTest do
       SomeTable.Quux.changeset(%SomeTable.Quux{}, %{
         title: :a,
         source: "qux",
-        content: %{length: 3},
+        content: %{quux_text: "abc"},
         is_special: false,
         is_last: true
       })

test/support/some_table/quux.ex

@@ -12,11 +12,22 @@ defmodule EctoDiscriminator.SomeTable.Quux do
     # make sure field types can contain calls on module attributes
     field :title, Ecto.Enum, values: Keyword.keys(@values)
     field :is_last, :boolean, virtual: true
+
+    embeds_one :content, Content, primary_key: false, on_replace: :update do
+      field :quux_text, :string
+    end
   end
 
   def changeset(struct, params \\ %{}) do
     struct
     |> cast_base(params)
     |> cast(params, [:title])
+    |> cast_embed(:content, required: true, with: &content_changeset/2)
+  end
+
+  def content_changeset(struct, params \\ %{}) do
+    struct
+    |> cast(params, [:quux_text])
+    |> validate_required([:quux_text])
   end
 end

test/support/some_table/qux.ex

@@ -8,12 +8,23 @@ defmodule EctoDiscriminator.SomeTable.Qux do
   # make sure base schemas can be referenced using alias
   schema Foo do
     field :is_special, :boolean
+
+    embeds_one :content, Content, primary_key: false, on_replace: :update do
+      field :text, :string
+    end
   end
 
   def changeset(struct, params \\ %{}) do
     struct
     |> cast_base(params)
     |> cast(params, [:is_special])
+    |> cast_embed(:content, required: true, with: &content_changeset/2)
     |> validate_required([:is_special])
   end
+
+  def content_changeset(struct, params \\ %{}) do
+    struct
+    |> cast(params, [:text])
+    |> validate_required([:text])
+  end
 end

test/support/some_table_pk.ex

@@ -13,7 +13,10 @@ defmodule EctoDiscriminator.SomeTablePk do
     # make sure field types can contain aliases and module attributes
     field :title, Enum, values: @values
 
-    belongs_to :not_pk, EctoDiscriminator.SomeTable, foreign_key: :type, references: :type, define_field: false
+    belongs_to :not_pk, EctoDiscriminator.SomeTable,
+      foreign_key: :type,
+      references: :type,
+      define_field: false
   end
 
   def changeset(struct, params \\ %{}) do