[codex] support polymorphic embeds

lib/field.ex

@@ -24,6 +24,8 @@ defmodule Strukt.Field do
     :field,
     :embeds_one,
     :embeds_many,
+    :polymorphic_embeds_one,
+    :polymorphic_embeds_many,
     :timestamps
   ]
 
@@ -41,6 +43,20 @@ defmodule Strukt.Field do
     for {type, meta, args} <- fields, do: parse(type, meta, args)
   end
 
+  defp parse(type, meta, [name, opts])
+       when type in [:polymorphic_embeds_one, :polymorphic_embeds_many] do
+    {validations, options} = Keyword.split(opts, @validation_opts)
+
+    %__MODULE__{
+      name: name,
+      type: type,
+      meta: meta,
+      value_type: PolymorphicEmbed,
+      options: options,
+      validations: validations
+    }
+  end
+
   defp parse(type, meta, [name, value_type]) when type in @supported_field_types,
     do: %__MODULE__{name: name, type: type, meta: meta, value_type: value_type}
 
@@ -93,6 +109,16 @@ defmodule Strukt.Field do
   def to_ast(%__MODULE__{type: :timestamps, meta: meta, options: options}),
     do: {:timestamps, meta, options}
 
+  def to_ast(%__MODULE__{
+        type: type,
+        name: name,
+        meta: meta,
+        options: options,
+        block: nil
+      })
+      when type in [:polymorphic_embeds_one, :polymorphic_embeds_many],
+      do: {type, meta, [name, options]}
+
   def to_ast(%__MODULE__{
         type: type,
         name: name,

lib/params.ex

@@ -78,11 +78,90 @@ defmodule Strukt.Params do
            cardinality: cardinality
          )}
 
+      {:parameterized, {PolymorphicEmbed, _opts}} ->
+        {field,
+         transform_polymorphic(module, field, value, get_struct_field_value(struct, field))}
+
+      {:array, {:parameterized, {PolymorphicEmbed, _opts}}} ->
+        {field,
+         transform_polymorphic(module, field, value, get_struct_field_value(struct, field),
+           cardinality: :many
+         )}
+
       _type ->
         {field, value}
     end
   end
 
+  defp transform_polymorphic(module, field, params, struct, opts \\ [])
+
+  # Keep nil as-is so required validation and PolymorphicEmbed's own handling can run later.
+  defp transform_polymorphic(_module, _field, nil, _struct, _opts), do: nil
+
+  # Struct params have already been cast by the caller, so leave them untouched.
+  defp transform_polymorphic(_module, _field, %_{} = params, _struct, _opts), do: params
+
+  # For polymorphic_embeds_many, transform each map using the matching current embed by index.
+  # Non-map structs in the list are preserved by the clause above.
+  defp transform_polymorphic(module, field, params, struct, cardinality: :many)
+       when is_list(params) do
+    current = List.wrap(struct)
+
+    params
+    |> Enum.with_index()
+    |> Enum.map(fn
+      {%_{} = param, _index} ->
+        param
+
+      {param, index} ->
+        transform_polymorphic(module, field, param, Enum.at(current, index))
+    end)
+  end
+
+  # Map params need the selected polymorphic module before source-field mapping can be applied.
+  # If the type cannot be inferred, keep the params unchanged and let cast_polymorphic_embed/3
+  # produce the configured error/raise/nilify behavior.
+  defp transform_polymorphic(module, field, params, struct, _opts) when is_map(params) do
+    case PolymorphicEmbed.get_polymorphic_module(module, field, params) do
+      nil ->
+        params
+
+      embedded_module ->
+        type_field_name = polymorphic_type_field_name(module, field)
+        type = get_params_field_value(params, type_field_name, nil)
+        struct = polymorphic_struct_for_module(struct, embedded_module)
+
+        embedded_module
+        |> transform(params, struct)
+        |> maybe_put_polymorphic_type(type_field_name, type)
+    end
+  rescue
+    _ -> params
+  end
+
+  # Leave invalid shapes alone so the eventual cast can report the type error.
+  defp transform_polymorphic(_module, _field, params, _struct, _opts), do: params
+
+  defp polymorphic_struct_for_module(struct, module) when is_struct(struct, module), do: struct
+  defp polymorphic_struct_for_module(_struct, _module), do: nil
+
+  # The type marker must be restored after source-field mapping, otherwise PolymorphicEmbed
+  # cannot infer which embedded schema to cast.
+  defp polymorphic_type_field_name(module, field) do
+    case module.__schema__(:type, field) do
+      {:parameterized, {PolymorphicEmbed, opts}} ->
+        opts.type_field_name
+
+      {:array, {:parameterized, {PolymorphicEmbed, opts}}} ->
+        opts.type_field_name
+    end
+  end
+
+  defp maybe_put_polymorphic_type(params, _type_field_name, nil), do: params
+
+  defp maybe_put_polymorphic_type(params, type_field_name, type),
+    do: Map.put(params, type_field_name, type)
+
   defp get_params_field_value(nil, _field, _struct), do: nil
 
   defp get_params_field_value(params, field, struct) when is_list(params) do

lib/strukt.ex

@@ -54,6 +54,8 @@ defmodule Strukt do
     :field,
     :embeds_one,
     :embeds_many,
+    :polymorphic_embeds_one,
+    :polymorphic_embeds_many,
     :belongs_to,
     :has_many,
     :has_one,
@@ -283,7 +285,12 @@ defmodule Strukt do
         {node, meta, elements} ->
           kvs =
             Keyword.merge(
-              [type: t, value_type: f.value_type, default: f.options[:default]],
+              [
+                type: t,
+                value_type: f.value_type,
+                default: f.options[:default],
+                types: f.options[:types]
+              ],
               f.validations
             )
 
@@ -297,6 +304,12 @@ defmodule Strukt do
     # Get a list of embeds valid for `cast_embed/3`
     cast_embed_fields = for %{type: t} = f <- fields, t in [:embeds_one, :embeds_many], do: f.name
 
+    # Get a list of polymorphic embeds valid for `PolymorphicEmbed.cast_polymorphic_embed/3`
+    cast_polymorphic_embed_fields =
+      for %{type: t} = f <- fields, t in [:polymorphic_embeds_one, :polymorphic_embeds_many] do
+        f.name
+      end
+
     # Expand fields back to their final AST form
     fields_ast =
       fields
@@ -321,6 +334,7 @@ defmodule Strukt do
 
         use Ecto.Schema
         import Ecto.Changeset, except: [change: 2]
+        import PolymorphicEmbed, only: [polymorphic_embeds_one: 2, polymorphic_embeds_many: 2]
 
         @behaviour unquote(__MODULE__)
         @before_compile unquote(__MODULE__)
@@ -358,6 +372,7 @@ defmodule Strukt do
         @schema_name Macro.underscore(__MODULE__)
         @validated_fields unquote(validated_fields)
         @cast_embed_fields unquote(Macro.escape(cast_embed_fields))
+        @cast_polymorphic_embed_fields unquote(Macro.escape(cast_polymorphic_embed_fields))
 
         # Ensure primary key can be cast, if applicable
         case Module.get_attribute(__MODULE__, :primary_key) do
@@ -444,12 +459,13 @@ defmodule Strukt do
         def change(entity_or_changeset, params) do
           case entity_or_changeset do
             %Ecto.Changeset{} = cs ->
-              cs
-              |> Ecto.Changeset.change(params)
-              |> validate()
+              entity = Ecto.Changeset.apply_changes(cs)
+              formed_params = Strukt.Params.transform(__MODULE__, params, entity)
+              changeset(cs, formed_params, cs.action)
 
             %__MODULE__{} = entity ->
-              changeset(entity, params, :update)
+              formed_params = Strukt.Params.transform(__MODULE__, params, entity)
+              changeset(entity, formed_params, :update)
           end
         end
 
@@ -493,7 +509,7 @@ defmodule Strukt do
           caller: __MODULE__,
           info: @validated_fields,
           fields: @cast_fields,
-          embeds: @cast_embed_fields
+          embeds: @cast_embed_fields ++ @cast_polymorphic_embed_fields
         })
 
       Code.eval_quoted(typespec_ast, [], __ENV__)
@@ -535,6 +551,28 @@ defmodule Strukt do
         cast(entity, params, @cast_fields)
         |> Map.put(:action, action)
         |> __cast_embeds__(@cast_embed_fields)
+        |> __cast_polymorphic_embeds__(@cast_polymorphic_embed_fields)
+        |> validate()
+      end
+
+      def changeset(%Ecto.Changeset{data: %__MODULE__{}} = changeset, params, action)
+          when action in [:insert, :update, :delete, nil] do
+        params =
+          case params do
+            %__MODULE__{} ->
+              Map.from_struct(params)
+
+            m when is_map(m) ->
+              m
+
+            other ->
+              Enum.into(other, %{})
+          end
+
+        cast(changeset, params, @cast_fields)
+        |> Map.put(:action, action)
+        |> __cast_embeds__(@cast_embed_fields)
+        |> __cast_polymorphic_embeds__(@cast_polymorphic_embed_fields)
         |> validate()
       end
 
@@ -574,6 +612,33 @@ defmodule Strukt do
         end
       end
 
+      defp __cast_polymorphic_embeds__(changeset, []), do: changeset
+
+      if length(@cast_polymorphic_embed_fields) > 0 do
+        defp __cast_polymorphic_embeds__(%Ecto.Changeset{params: params} = changeset, [
+               field | fields
+             ]) do
+          f = to_string(field)
+
+          changeset =
+            case Map.get(params, f) do
+              nil ->
+                changeset
+
+              %_{} = entity ->
+                Ecto.Changeset.put_change(changeset, field, entity)
+
+              [%_{} | _] = entities ->
+                Ecto.Changeset.put_change(changeset, field, entities)
+
+              _other ->
+                PolymorphicEmbed.cast_polymorphic_embed(changeset, field)
+            end
+
+          __cast_polymorphic_embeds__(changeset, fields)
+        end
+      end
+
       @doc """
       Applies the changes in the changset if the changeset is valid, returning the
       updated data. The action must be one of `:insert`, `:update`, or `:delete` and
@@ -592,7 +657,7 @@ defmodule Strukt do
       @doc "Deserialize this type from a JSON string or iodata"
       @spec from_json(binary | iodata) :: {:ok, t} | {:error, reason :: term}
       def from_json(input) do
-        with {:ok, map} <- Jason.decode(input, keys: :atoms!, strings: :copy) do
+        with {:ok, map} <- Jason.decode(input, strings: :copy) do
           {:ok, Ecto.embedded_load(__MODULE__, map, :json)}
         end
       end

lib/typespec.ex

@@ -82,6 +82,19 @@ defmodule Strukt.Typespec do
 
         {name, %{type: :embeds_many, value_type: type}} ->
           {name, List.wrap(compose_call(type, :t, []))}
+
+        {name, %{type: :polymorphic_embeds_one, types: types} = meta} ->
+          required? = Map.get(meta, :required) == true
+          type_name = polymorphic_type_name(types)
+
+          if required? do
+            {name, type_name}
+          else
+            {name, nilable(type_name)}
+          end
+
+        {name, %{type: :polymorphic_embeds_many, types: types}} ->
+          {name, List.wrap(polymorphic_type_name(types))}
       end)
 
     # Join all fields together
@@ -104,6 +117,24 @@ defmodule Strukt.Typespec do
 
   defp nilable(type_name), do: {:|, [], [type_name, nil]}
 
+  defp polymorphic_type_name(types) when is_list(types) do
+    types
+    |> Enum.map(fn
+      {_type, type_opts} when is_list(type_opts) ->
+        Keyword.fetch!(type_opts, :module)
+
+      {_type, module} ->
+        module
+    end)
+    |> Enum.map(&compose_call(&1, :t, []))
+    |> union()
+  end
+
+  defp polymorphic_type_name(_types), do: primitive(:any)
+
+  defp union([type]), do: type
+  defp union([type | types]), do: {:|, [], [type, union(types)]}
+
   defp type_to_type_name(:id), do: primitive(:non_neg_integer)
   defp type_to_type_name(:binary_id), do: primitive(:binary)
   defp type_to_type_name(:integer), do: primitive(:integer)

mix.exs

@@ -52,6 +52,7 @@ defmodule Strukt.MixProject do
   defp deps do
     [
       {:ecto, "~> 3.12"},
+      {:polymorphic_embed, "~> 5.0"},
       {:jason, "> 0.0.0", optional: true},
       {:ex_doc, "> 0.0.0", only: [:docs], runtime: false}
     ]

mix.lock

@@ -1,4 +1,5 @@
 %{
+  "attrs": {:hex, :attrs, "0.6.0", "25d738b47829f964a786ef73897d2550b66f3e7d1d7c49a83bc8fd81c71bed93", [:mix], [], "hexpm", "9c30ac15255c2ba8399263db55ba32c2f4e5ec267b654ce23df99168b405c82e"},
   "decimal": {:hex, :decimal, "2.3.0", "3ad6255aa77b4a3c4f818171b12d237500e63525c2fd056699967a3e7ea20f62", [:mix], [], "hexpm", "a4d66355cb29cb47c3cf30e71329e58361cfcb37c34235ef3bf1d7bf3773aeac"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.29", "149d50dcb3a93d9f3d6f3ecf18c918fb5a2d3c001b5d3305c926cddfbd33355b", [:mix], [], "hexpm", "4902af1b3eb139016aed210888748db8070b8125c2342ce3dcae4f38dcc63503"},
   "ecto": {:hex, :ecto, "3.13.4", "27834b45d58075d4a414833d9581e8b7bb18a8d9f264a21e42f653d500dbeeb5", [:mix], [{:decimal, "~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "5ad7d1505685dfa7aaf86b133d54f5ad6c42df0b4553741a1ff48796736e88b2"},
@@ -8,5 +9,6 @@
   "makeup_elixir": {:hex, :makeup_elixir, "0.16.0", "f8c570a0d33f8039513fbccaf7108c5d750f47d8defd44088371191b76492b0b", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "28b2cbdc13960a46ae9a8858c4bebdec3c9a6d7b4b9e7f4ed1502f8159f338e7"},
   "makeup_erlang": {:hex, :makeup_erlang, "0.1.1", "3fcb7f09eb9d98dc4d208f49cc955a34218fc41ff6b84df7c75b3e6e533cc65f", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "174d0809e98a4ef0b3309256cbf97101c6ec01c4ab0b23e926a9e17df2077cbb"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.2.3", "244836e6e3f1200c7f30cb56733fd808744eca61fd182f731eac4af635cc6d0b", [:mix], [], "hexpm", "c8d789e39b9131acf7b99291e93dae60ab48ef14a7ee9d58c6964f59efb570b0"},
+  "polymorphic_embed": {:hex, :polymorphic_embed, "5.0.6", "58d8c5fe3df3c0cf1e3b8990318cf93489360fbaea555d9520f0b50577ea7e5b", [:mix], [{:attrs, "~> 0.6", [hex: :attrs, repo: "hexpm", optional: false]}, {:ecto, "~> 3.12", [hex: :ecto, repo: "hexpm", optional: false]}, {:jason, "~> 1.4", [hex: :jason, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 4.1", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:phoenix_html_helpers, "~> 1.0", [hex: :phoenix_html_helpers, repo: "hexpm", optional: true]}, {:phoenix_live_view, "~> 0.20 or ~> 1.0", [hex: :phoenix_live_view, repo: "hexpm", optional: true]}], "hexpm", "99c7a7aed3d4b00bd08ce91c9b880deaa47b649904fca8b745f3a50b9b3b3835"},
   "telemetry": {:hex, :telemetry, "1.3.0", "fedebbae410d715cf8e7062c96a1ef32ec22e764197f70cda73d82778d61e7a2", [:rebar3], [], "hexpm", "7015fc8919dbe63764f4b4b87a95b7c0996bd539e0d499be6ec9d7f3875b79e6"},
 }