improvement: add optimized path for casting embeds when they are simple

improvement: add `include_embedded_source_by_default?` config to optimize embeds
improvement: support `:fields` constraint on `:struct` type, enabling persistence

benchmarks/embedded_resources.exs

@@ -1,9 +1,17 @@
+defmodule Domain do
+  use Ash.Domain, validate_config_inclusion?: false
+
+  resources do
+    allow_unregistered? true
+  end
+end
+
 defmodule Embed do
   use Ash.Resource, data_layer: :embedded
 
   attributes do
     # uuid_primary_key :id
-    attribute :name, :string
+    attribute :name, :string, public?: true
   end
 
   actions do
@@ -17,8 +25,21 @@ defmodule Resource do
 
   attributes do
     uuid_primary_key :id
-    attribute :embeds, {:array, Embed}
-    attribute :maps, {:array, :map}
+    attribute :embeds, {:array, Embed}, public?: true
+    attribute :structs, {:array, :struct} do
+      public? true
+      constraints [
+        items: [
+          instance_of: Embed,
+          fields: [
+            name: [
+              type: :string
+            ]
+          ]
+        ]
+      ]
+    end
+    attribute :maps, {:array, :map}, public?: true
   end
 
   actions do
@@ -27,16 +48,20 @@ defmodule Resource do
   end
 end
 
-defmodule Domain do
-  use Ash.Domain
-
-  resources do
-    resource Resource
-  end
-end
-
 embeds_input = 1..100 |> Enum.map(&%{name: "Embed #{&1}"})
 
+resource_embeds_input =
+  1..100
+  |> Enum.map(fn _ -> %{embeds: embeds_input} end)
+
+resource_maps_input =
+  1..100
+  |> Enum.map(fn _ -> %{maps: embeds_input} end)
+
+resource_structs_input =
+  1..100
+  |> Enum.map(fn _ -> %{structs: embeds_input} end)
+
 Resource
 |> Ash.Changeset.for_create(:create, %{embeds: embeds_input, maps: embeds_input})
 |> Ash.create!()
@@ -44,14 +69,14 @@ Resource
 Benchee.run(
   %{
     embeds: fn ->
-      Resource
-      |> Ash.Changeset.for_create(:create, %{embeds: embeds_input})
-      |> Ash.create!()
+      Ash.bulk_create!(resource_embeds_input, Resource, :create)
     end,
     maps: fn ->
-      Resource
-      |> Ash.Changeset.for_create(:create, %{maps: embeds_input})
-      |> Ash.create!()
+      Ash.bulk_create!(resource_maps_input, Resource, :create)
+    end,
+    structs: fn ->
+      Ash.bulk_create!(resource_structs_input, Resource, :create)
     end
-  }
+  },
+    memory_time: 2
 )

documentation/tutorials/get-started.md

@@ -236,7 +236,7 @@ defmodule Helpdesk.Support.Ticket do
 end
 ```
 
-Next, add your domain to your `config.exs`
+Next, add your domain to your `config.exs`, and configure some backwards compatibility configuration.
 
 Run the following to create your `config.exs` if it doesn't already exist
 
@@ -252,6 +252,8 @@ and add the following contents to it.
 import Config
 
 config :helpdesk, :ash_domains, [Helpdesk.Support]
+
+config :include_embedded_source_by_default?, true
 ```
 
 ### Try our first resource out

lib/ash/embeddable_type.ex

@@ -1,6 +1,12 @@
 defmodule Ash.EmbeddableType do
   @moduledoc false
 
+  @include_source_by_default Application.compile_env(
+                               :ash,
+                               :include_embedded_source_by_default?,
+                               true
+                             )
+
   @embedded_resource_array_constraints [
     sort: [
       type: :any,
@@ -56,6 +62,12 @@ defmodule Ash.EmbeddableType do
       type: :atom,
       doc: "The read action to use when reading the embed. The primary is used by default."
     ],
+    include_source?: [
+      type: :boolean,
+      default: @include_source_by_default,
+      doc:
+        "Whether to include the source changeset in the context. Defaults to the value of `config :ash, :include_embedded_source_by_default`, or `true`. In 4.x, the default will be `false`."
+    ],
     __source__: [
       type: :any,
       hide: true,
@@ -144,6 +156,11 @@ defmodule Ash.EmbeddableType do
   defmacro single_embed_implementation(opts) do
     # credo:disable-for-next-line Credo.Check.Refactor.LongQuoteBlocks
     quote generated: true, location: :keep, bind_quoted: [opts: opts] do
+      @include_source_by_default Application.compile_env(
+                                   :ash,
+                                   :include_embedded_source_by_default?,
+                                   true
+                                 )
       alias Ash.EmbeddableType.ShadowDomain
 
       def storage_type(_), do: :map
@@ -199,56 +216,156 @@ defmodule Ash.EmbeddableType do
 
       def cast_input_array(value, constraints) when is_list(value) do
         action =
-          constraints[:create_action] ||
-            Ash.Resource.Info.primary_action!(__MODULE__, :create).name
+          case constraints[:create_action] do
+            nil ->
+              Ash.Resource.Info.primary_action!(__MODULE__, :create)
+
+            action ->
+              Ash.Resource.Info.action(__MODULE__, action)
+          end
 
         {structs, values} =
           value
           |> Stream.with_index()
           |> Enum.split_with(&is_struct(elem(&1, 0), __MODULE__))
 
-        {context, opts} =
-          case constraints[:__source__] do
-            %Ash.Changeset{context: context} = source ->
-              {Map.put(context, :__source__, source),
-               Ash.Context.to_opts(context[:private] || %{})}
+        if Enum.empty?(values) do
+          {:ok, Enum.map(structs, &elem(&1, 0))}
+        else
+          skip_unknown_inputs = List.wrap(constraints[:skip_unknown_inputs])
 
-            _ ->
-              {%{}, []}
-          end
+          # This is a simplified, tight-loop version of resource creation
+          if !constraints[:include_source?] &&
+               Enum.empty?(action.changes) &&
+               Enum.empty?(Ash.Resource.Info.changes(__MODULE__, action.type)) &&
+               Enum.empty?(Ash.Resource.Info.validations(__MODULE__, action.type)) &&
+               Enum.empty?(Ash.Resource.Info.notifiers(__MODULE__)) &&
+               Enum.empty?(Ash.Resource.Info.relationships(__MODULE__)) do
+            Enum.reduce_while(values, {:ok, []}, fn {value, index}, {:ok, results} ->
+              Enum.reduce_while(value, {:ok, index, %{__struct__: __MODULE__}}, fn {key, value},
+                                                                                   {:ok, index,
+                                                                                    acc} ->
+                case Ash.Resource.Info.attribute(__MODULE__, key) do
+                  nil ->
+                    {:cont, {:ok, acc}}
 
-        values
-        |> Stream.map(&elem(&1, 0))
-        |> Ash.bulk_create(
-          __MODULE__,
-          action,
-          Keyword.merge(opts,
-            domain: ShadowDomain,
-            context: context,
-            sorted?: true,
-            skip_unknown_inputs: skip_unknown_inputs(constraints),
-            return_records?: true,
-            return_errors?: true,
-            batch_size: 1_000_000_000
-          )
-        )
-        |> case do
-          %{status: :success, records: records} ->
-            Enum.reduce(structs, {:ok, records}, fn {struct, index}, {:ok, records} ->
-              {:ok, List.insert_at(records, index, struct)}
-            end)
-
-          %{errors: errors} ->
-            errors =
-              Enum.map(errors, fn
-                %Ash.Changeset{context: %{bulk_create: %{index: index}}, errors: errors} ->
-                  Ash.Error.set_path(Ash.Error.to_ash_error(errors), index)
-
-                other ->
-                  Ash.Error.to_ash_error(other)
+                  attribute ->
+                    if attribute.name in action.accept do
+                      with value <- Ash.Type.Helpers.handle_indexed_maps(attribute.type, value),
+                           {:ok, casted} <-
+                             Ash.Type.cast_input(attribute.type, value, attribute.constraints),
+                           {:ok, casted} <-
+                             Ash.Type.apply_constraints(
+                               attribute.type,
+                               casted,
+                               attribute.constraints
+                             ) do
+                        {:cont, {:ok, index, Map.put(acc, key, casted)}}
+                      else
+                        {:error, error} ->
+                          {:halt, {:error, index, error}}
+                      end
+                    else
+                      if Enum.any?(skip_unknown_inputs, &(&1 == :* || &1 == key)) do
+                        {:cont, {:ok, index, acc}}
+                      else
+                        {:halt,
+                         {:error, index,
+                          Ash.Error.Invalid.NoSuchInput.exception(
+                            resource: __MODULE__,
+                            action: action.name,
+                            input: key,
+                            inputs: Ash.Resource.Info.action_inputs(__MODULE__, action.name)
+                          )}}
+                      end
+                    end
+                end
               end)
+              |> case do
+                {:ok, index, result} ->
+                  __MODULE__
+                  |> Ash.Resource.Info.attributes()
+                  |> Stream.filter(
+                    &(&1.name not in action.allow_nil_input &&
+                        (&1.allow_nil? == false || &1.name in action.require_attributes))
+                  )
+                  |> Enum.reduce_while({:ok, result}, fn attr, {:ok, result} ->
+                    if is_nil(Map.get(result, attr.name)) do
+                      {:halt,
+                       {:error,
+                        Ash.Error.Changes.Required.exception(
+                          resource: __MODULE__,
+                          field: attr.name,
+                          type: :attribute
+                        )}}
+                    else
+                      {:cont, {:ok, result}}
+                    end
+                  end)
+                  |> case do
+                    {:ok, result} ->
+                      {:cont, {:ok, [result | results]}}
 
-            {:error, Ash.Error.to_ash_error(errors)}
+                    {:error, error} ->
+                      {:halt, {:error, index, error}}
+                  end
+
+                {:error, index, error} ->
+                  {:halt, {:error, index, error}}
+              end
+            end)
+            |> case do
+              {:ok, values} ->
+                {:ok, Enum.reverse(values)}
+
+              {:error, index, error} ->
+                {:error, Ash.Error.set_path(Ash.Error.to_ash_error(error), index)}
+            end
+          else
+            {context, opts} =
+              case constraints[:__source__] do
+                %Ash.Changeset{context: context} = source ->
+                  {Map.put(context, :__source__, source),
+                   Ash.Context.to_opts(context[:private] || %{})}
+
+                _ ->
+                  {%{}, []}
+              end
+
+            values
+            |> Stream.map(&elem(&1, 0))
+            |> Ash.bulk_create(
+              __MODULE__,
+              action.name,
+              Keyword.merge(opts,
+                domain: ShadowDomain,
+                context: context,
+                sorted?: true,
+                skip_unknown_inputs: skip_unknown_inputs(constraints),
+                return_records?: true,
+                return_errors?: true,
+                batch_size: 1_000_000_000
+              )
+            )
+            |> case do
+              %{status: :success, records: records} ->
+                Enum.reduce(structs, {:ok, records}, fn {struct, index}, {:ok, records} ->
+                  {:ok, List.insert_at(records, index, struct)}
+                end)
+
+              %{errors: errors} ->
+                errors =
+                  Enum.map(errors, fn
+                    %Ash.Changeset{context: %{bulk_create: %{index: index}}, errors: errors} ->
+                      Ash.Error.set_path(Ash.Error.to_ash_error(errors), index)
+
+                    other ->
+                      Ash.Error.to_ash_error(other)
+                  end)
+
+                {:error, Ash.Error.to_ash_error(errors)}
+            end
+          end
         end
       end
 
@@ -806,7 +923,11 @@ defmodule Ash.EmbeddableType do
       end
 
       def include_source(constraints, changeset) do
-        Keyword.put(constraints, :__source__, changeset)
+        if Keyword.get(constraints, :include_source?, @include_source_by_default) do
+          Keyword.put(constraints, :__source__, changeset)
+        else
+          constraints
+        end
       end
 
       def prepare_change_array(_old_values, nil, _constraints) do

lib/ash/type/decimal_comp.ex

@@ -1 +0,0 @@
-

lib/ash/type/map.ex

@@ -107,8 +107,8 @@ defmodule Ash.Type.Map do
 
   @impl true
   def cast_atomic(new_value, constraints) do
-    if constraints[:keys] do
-      {:not_atomic, "Keywords do not support atomic updates when using the `keys` constraint"}
+    if constraints[:fields] do
+      {:not_atomic, "Maps do not support atomic updates when using the `fields` constraint"}
     else
       {:atomic, new_value}
     end

lib/ash/type/struct.ex

@@ -1,19 +1,79 @@
 defmodule Ash.Type.Struct do
-  @moduledoc """
-  Represents a struct.
-
-  This cannot be loaded from a database, it can only be used to cast input.
-
-  Use the `instance_of` constraint to specify that it must be an instance of a specific struct.
-  """
-  use Ash.Type
-
   @constraints [
     instance_of: [
       type: :atom,
       doc: "The module the struct should be an instance of"
+    ],
+    preserve_nil_values?: [
+      type: :boolean,
+      default: false,
+      doc:
+        "If set to true, when storing, nil values will be kept. Otherwise, nil values will be omitted."
+    ],
+    fields: [
+      type: :keyword_list,
+      keys: [
+        *: [
+          type: :keyword_list,
+          keys: [
+            type: [
+              type: Ash.OptionsHelpers.ash_type(),
+              required: true
+            ],
+            allow_nil?: [
+              type: :boolean,
+              default: true
+            ],
+            constraints: [
+              type: :keyword_list,
+              default: []
+            ]
+          ]
+        ]
+      ],
+      doc: """
+      The types of the fields in the struct, and their constraints.
+
+      For example:
+
+          fields:  [
+            amount: [
+              type: :integer,
+              constraints: [
+                max: 10
+              ]
+            ],
+            currency: [
+              type: :string,
+              allow_nil?: false,
+              constraints: [
+                max_length: 3
+              ]
+            ]
+          ]
+
+      allow_nil? is true by default
+      """
     ]
   ]
+  @moduledoc """
+  Represents a struct.
+
+  Use the `instance_of` constraint to specify that it must be an instance of a specific struct.
+
+  This cannot be loaded from a database unless the `instance_of` constraint is provided.
+  If not, it can only be used to cast input, i.e for arguments.
+
+  ## Constraints
+
+  #{Spark.Options.docs(@constraints)}
+  """
+
+  def field_types(value) do
+    {:ok, value}
+  end
+
+  use Ash.Type
 
   @impl true
   def constraints, do: @constraints
@@ -22,77 +82,227 @@ defmodule Ash.Type.Struct do
   def storage_type(_), do: :map
 
   @impl true
+  def matches_type?(v, constraints) do
+    if instance_of = constraints[:instance_of] do
+      is_struct(v, instance_of)
+    else
+      is_struct(v)
+    end
+  end
+
+  @impl true
+  def cast_input("", _), do: {:ok, nil}
+
   def cast_input(nil, _), do: {:ok, nil}
 
-  def cast_input(%struct{} = value, constraints) do
-    case constraints[:instance_of] do
-      nil ->
-        {:ok, value}
-
-      ^struct ->
-        {:ok, value}
+  def cast_input(value, constraints) when is_binary(value) do
+    case Jason.decode(value) do
+      {:ok, value} ->
+        cast_input(value, constraints)
 
       _ ->
         :error
     end
   end
 
+  def cast_input(value, _) when is_map(value), do: {:ok, value}
   def cast_input(_, _), do: :error
 
-  @impl true
-  def matches_type?(v, _) do
-    is_struct(v)
-  end
-
-  @impl Ash.Type
-  def load(record, load, _constraints, %{domain: domain} = context) do
-    opts = Ash.Context.to_opts(context, domain: domain)
-
-    Ash.load(record, load, opts)
-  end
-
-  @impl Ash.Type
-  def merge_load(left, right, constraints, context) do
-    instance_of = constraints[:instance_of]
-    left = Ash.Query.load(instance_of, left)
-    right = Ash.Query.load(instance_of, right)
-
-    if left.valid? do
-      {:ok, Ash.Query.merge_query_load(left, right, context)}
-    else
-      {:error, Ash.Error.to_ash_error(left.errors)}
-    end
-  end
-
-  @impl Ash.Type
-  def get_rewrites(merged_load, calculation, path, constraints) do
-    instance_of = constraints[:instance_of]
-
-    if instance_of && Ash.Resource.Info.resource?(instance_of) do
-      merged_load = Ash.Query.load(instance_of, merged_load)
-      Ash.Actions.Read.Calculations.get_all_rewrites(merged_load, calculation, path)
-    else
-      []
-    end
-  end
-
-  @impl Ash.Type
-  def rewrite(value, rewrites, _constraints) do
-    Ash.Actions.Read.Calculations.rewrite(rewrites, value)
-  end
-
-  @impl Ash.Type
-  def can_load?(constraints) do
-    instance_of = constraints[:instance_of]
-
-    instance_of && Ash.Resource.Info.resource?(instance_of)
-  end
-
   @impl true
   def cast_stored(nil, _), do: {:ok, nil}
+
+  def cast_stored(value, constraints) when is_map(value) do
+    if fields = constraints[:fields] do
+      if constraints[:instance_of] do
+        nil_values = constraints[:store_nil_values?]
+
+        Enum.reduce_while(fields, {:ok, %{}}, fn {key, config}, {:ok, acc} ->
+          case Map.fetch(value, key) do
+            {:ok, value} ->
+              case Ash.Type.cast_stored(config[:type], value, config[:constraints] || []) do
+                {:ok, value} ->
+                  if is_nil(value) && !nil_values do
+                    {:cont, {:ok, acc}}
+                  else
+                    {:cont, {:ok, Map.put(acc, key, value)}}
+                  end
+
+                other ->
+                  {:halt, other}
+              end
+
+            :error ->
+              {:cont, {:ok, acc}}
+          end
+        end)
+      else
+        :error
+      end
+    else
+      :error
+    end
+  end
+
   def cast_stored(_, _), do: :error
 
   @impl true
   def dump_to_native(nil, _), do: {:ok, nil}
+
+  def dump_to_native(value, constraints) when is_map(value) do
+    if fields = constraints[:fields] do
+      if constraints[:instance_of] do
+        Enum.reduce_while(fields, {:ok, %{}}, fn {key, config}, {:ok, acc} ->
+          case Map.fetch(value, key) do
+            {:ok, value} ->
+              case Ash.Type.dump_to_native(config[:type], value, config[:constraints] || []) do
+                {:ok, value} ->
+                  {:cont, {:ok, Map.put(acc, key, value)}}
+
+                other ->
+                  {:halt, other}
+              end
+
+            :error ->
+              {:cont, {:ok, acc}}
+          end
+        end)
+      else
+        :error
+      end
+    else
+      :error
+    end
+  end
+
   def dump_to_native(_, _), do: :error
+
+  @impl true
+  def cast_atomic(new_value, constraints) do
+    if constraints[:fields] do
+      {:not_atomic, "Structs do not support atomic updates when using the `keys` constraint"}
+    else
+      {:atomic, new_value}
+    end
+  end
+
+  @impl true
+  def apply_constraints(value, constraints) do
+    with {:ok, value} <- handle_fields(value, constraints) do
+      handle_instance_of(value, constraints)
+    end
+  end
+
+  defp handle_fields(value, constraints) do
+    case Keyword.fetch(constraints, :fields) do
+      {:ok, fields} when is_list(fields) ->
+        check_fields(value, fields)
+
+      _ ->
+        {:ok, value}
+    end
+  end
+
+  defp handle_instance_of(value, constraints) do
+    case Keyword.fetch(constraints, :instance_of) do
+      {:ok, struct} ->
+        cond do
+          is_struct(value, struct) ->
+            {:ok, value}
+
+          is_struct(value) ->
+            :error
+
+          value ->
+            if constraints[:fields] do
+              {:ok, struct(struct, value)}
+            else
+              keys = Map.keys(value)
+
+              cond do
+                Enum.all?(keys, &is_atom/1) ->
+                  {:ok, struct(struct, value)}
+
+                Enum.all?(keys, &is_binary/1) ->
+                  {:ok, Map.delete(struct.__struct__, :__struct__)}
+                  |> Enum.reduce({:ok, struct(struct)}, fn {key, _value}, {:ok, acc} ->
+                    case Map.fetch(value, to_string(key)) do
+                      {:ok, val} ->
+                        {:ok, Map.put(acc, key, val)}
+
+                      :error ->
+                        {:ok, acc}
+                    end
+                  end)
+              end
+            end
+        end
+
+      :error ->
+        if is_struct(value) do
+          {:ok, value}
+        else
+          :error
+        end
+    end
+  end
+
+  defp check_fields(value, fields) do
+    Enum.reduce(fields, {:ok, %{}}, fn
+      {field, field_constraints}, {:ok, checked_value} ->
+        case fetch_field(value, field) do
+          {:ok, field_value} ->
+            check_field(checked_value, field, field_value, field_constraints)
+
+          :error ->
+            if field_constraints[:allow_nil?] == false do
+              {:error, [[message: "field must be present", field: field]]}
+            else
+              {:ok, checked_value}
+            end
+        end
+
+      {_, _}, {:error, errors} ->
+        {:error, errors}
+    end)
+  end
+
+  defp check_field(result, field, field_value, field_constraints) do
+    case Ash.Type.cast_input(
+           field_constraints[:type],
+           field_value,
+           field_constraints[:constraints] || []
+         ) do
+      {:ok, field_value} ->
+        case Ash.Type.apply_constraints(
+               field_constraints[:type],
+               field_value,
+               field_constraints[:constraints] || []
+             ) do
+          {:ok, nil} ->
+            if field_constraints[:allow_nil?] == false do
+              {:error, [[message: "value must not be nil", field: field]]}
+            else
+              {:ok, Map.put(result, field, nil)}
+            end
+
+          {:ok, field_value} ->
+            {:ok, Map.put(result, field, field_value)}
+
+          {:error, errors} ->
+            {:error, Enum.map(errors, fn error -> Keyword.put(error, :field, field) end)}
+        end
+
+      :error ->
+        {:error, [[message: "invalid value", field: field]]}
+    end
+  end
+
+  defp fetch_field(map, atom) when is_atom(atom) do
+    case Map.fetch(map, atom) do
+      {:ok, value} -> {:ok, value}
+      :error -> fetch_field(map, to_string(atom))
+    end
+  end
+
+  defp fetch_field(map, key), do: Map.fetch(map, key)
 end

lib/mix/tasks/install/ash.install.ex

@@ -53,6 +53,12 @@ defmodule Mix.Tasks.Ash.Install do
       :"Ash.Domain",
       @domain_default_section_order
     )
+    |> Igniter.Project.Config.configure(
+      "config.exs",
+      :ash,
+      [:include_embedded_source_by_default?],
+      true
+    )
     |> then(fn igniter ->
       if "--example" in argv do
         generate_example(igniter, argv)

test/actions/bulk/bulk_create_test.exs

@@ -989,19 +989,23 @@ defmodule Ash.Test.Actions.BulkCreateTest do
         |> Ash.create!()
 
       assert [_] =
-               [%{title: "title1", authorize?: true}, %{title: "title2", authorize?: true}]
+               [
+                 %{title: "title1", authorize?: true},
+                 %{title: "title2", authorize?: true},
+                 %{title: "title3", authorize?: true}
+               ]
                |> Ash.bulk_create!(
                  Post,
                  :create_with_policy,
                  tenant: org.id,
                  authorize?: true,
-                 batch_size: 1,
+                 batch_size: 2,
                  return_records?: true,
                  return_stream?: true
                )
                |> Enum.take(1)
 
-      assert Ash.count!(Post, authorize?: false) == 1
+      assert Ash.count!(Post, authorize?: false) == 2
     end
 
     test "by returning notifications, you get the notifications in the stream" do

test/type/struct_test.exs

@@ -0,0 +1,188 @@
+defmodule Type.StructTest do
+  use ExUnit.Case, async: true
+
+  alias Ash.Test.Domain, as: Domain
+
+  defmodule Metadata do
+    defstruct [:foo, :bar]
+  end
+
+  defmodule Post do
+    @moduledoc false
+    use Ash.Resource, domain: Domain, data_layer: Ash.DataLayer.Ets
+
+    ets do
+      private?(true)
+    end
+
+    actions do
+      default_accept :*
+      defaults [:read, :destroy, create: :*, update: :*]
+    end
+
+    attributes do
+      uuid_primary_key :id
+
+      attribute :metadata, :struct do
+        public? true
+
+        constraints instance_of: Metadata,
+                    fields: [
+                      foo: [type: :string, allow_nil?: false],
+                      bar: [type: :integer, constraints: [min: 0]]
+                    ]
+      end
+    end
+  end
+
+  test "it handles valid maps" do
+    changeset =
+      Post
+      |> Ash.Changeset.for_create(:create, %{
+        metadata: %{
+          foo: "bar",
+          bar: 1
+        }
+      })
+
+    assert changeset.valid?
+  end
+
+  test "allow_nil? is true by default" do
+    changeset =
+      Post
+      |> Ash.Changeset.for_create(:create, %{
+        metadata: %{
+          foo: "bar",
+          bar: "2"
+        }
+      })
+
+    assert changeset.valid?
+
+    assert changeset.attributes == %{
+             metadata: %Metadata{foo: "bar", bar: 2}
+           }
+  end
+
+  test "cast result has only atom keys" do
+    changeset =
+      Post
+      |> Ash.Changeset.for_create(:create, %{
+        metadata: %{
+          "bar" => nil,
+          foo: "bar"
+        }
+      })
+
+    assert changeset.valid?
+
+    assert changeset.attributes == %{
+             metadata: %Metadata{foo: "bar", bar: nil}
+           }
+  end
+
+  test "keys that can be nil don't need to be there" do
+    changeset =
+      Post
+      |> Ash.Changeset.for_create(:create, %{
+        metadata: %{
+          foo: "bar"
+        }
+      })
+
+    assert changeset.valid?
+  end
+
+  test "keys that can not be nil need to be there" do
+    changeset =
+      Post
+      |> Ash.Changeset.for_create(:create, %{
+        metadata: %{bar: 1}
+      })
+
+    refute changeset.valid?
+
+    assert [
+             %Ash.Error.Changes.InvalidAttribute{
+               field: :foo,
+               message: "field must be present",
+               private_vars: nil,
+               value: %{bar: 1},
+               bread_crumbs: [],
+               vars: [],
+               path: [:metadata]
+             }
+           ] = changeset.errors
+  end
+
+  test "constraints of field types are checked" do
+    changeset =
+      Post
+      |> Ash.Changeset.for_create(:create, %{
+        metadata: %{foo: "hello", bar: -1}
+      })
+
+    refute changeset.valid?
+
+    assert [
+             %Ash.Error.Changes.InvalidAttribute{
+               field: :bar,
+               message: "must be more than or equal to %{min}",
+               private_vars: nil,
+               value: %{bar: -1, foo: "hello"},
+               bread_crumbs: [],
+               vars: [min: 0],
+               path: [:metadata]
+             }
+           ] = changeset.errors
+  end
+
+  test "extra fields are removed" do
+    changeset =
+      Post
+      |> Ash.Changeset.for_create(
+        :create,
+        %{
+          metadata: %{
+            "foo" => "bar",
+            extra: "field"
+          }
+        }
+      )
+
+    assert changeset.valid?
+
+    assert changeset.attributes == %{
+             metadata: %Metadata{foo: "bar"}
+           }
+  end
+
+  test "values are casted before checked" do
+    changeset =
+      Post
+      |> Ash.Changeset.for_create(
+        :create,
+        %{
+          metadata: %{
+            "foo" => "",
+            bar: "2"
+          }
+        }
+      )
+
+    refute changeset.valid?
+
+    assert [
+             %Ash.Error.Changes.InvalidAttribute{
+               field: :foo,
+               message: "value must not be nil",
+               private_vars: nil,
+               value: %{:bar => "2", "foo" => ""},
+               bread_crumbs: [],
+               vars: [],
+               path: [:metadata]
+             }
+           ] = changeset.errors
+  end
+end