diff --git a/.gitignore b/.gitignore
index 44fba26034..943c1c1b7b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,13 @@
+# Intellij
+.idea/
+installer/phx_new.iml
+installer/templates/phx_single/phx_single.iml
+installer/templates/phx_umbrella/apps/app_name/app_name.iml
+installer/templates/phx_umbrella/apps/app_name_web/app_name_web.iml
+installer/templates/phx_umbrella/phx_umbrella.iml
+integration_test/phoenix_integration.iml
+phoenix.iml
+
 /_build/
 /deps/
 /doc/
diff --git a/lib/mix/phoenix/custom_generator_behavior.ex b/lib/mix/phoenix/custom_generator_behavior.ex
new file mode 100644
index 0000000000..39024583ef
--- /dev/null
+++ b/lib/mix/phoenix/custom_generator_behavior.ex
@@ -0,0 +1,82 @@
+defmodule Mix.Phoenix.CustomGeneratorBehaviour do
+  @moduledoc """
+  This module defines the behavior for custom generators.
+  Implement modules that implement this behavior and use with mix phx.gen.live,phx.gen.schema,phx.gen.context to
+  extend default generators with project specific types and form components.
+
+  For example if using a postgres user type enums you can use type_for_migration/1 to return the user type as an atom and
+  type_and_opts_for_schema/1 to return an Ecto.Enum, values: [] string
+  by implementing a custom generator along the lines of MyProject.CustomEnumGenerator passed to mix phx.gen.schema as
+  "field:MyProject.CustomEnumGenerator:custom_user_type:list:of:allowed:values"
+  """
+
+  @doc """
+  Unpack custom generator and it's options.
+  Return {key, {:custom, __MODULE__, unpacked_options | nil}}
+  """
+  @callback validate_attr!(attrs :: tuple) :: {name :: atom, {:custom, provider :: atom, opts :: any}} | {term, term}
+
+  @doc """
+  return the string that will be used to populate schema field e.g. a string like "Ecto.Enum, values: [:a,:b,:c]"
+  """
+  @callback type_and_opts_for_schema(attrs :: any) :: String.t()
+
+  @doc """
+  return the ecto migration field type term. e.g. {:enum, [:a,:b,:c]}
+  """
+  @callback type_for_migration(opts :: any) :: term
+
+  @doc """
+  return the default value for the field type used by live view and ecto tests.
+  """
+  @callback type_to_default(key :: atom, opts :: any, action :: atom) :: any
+
+  @doc """
+  return the input/live component used to display this custom field type in a live view form.
+  """
+  @callback live_form_input(key :: atom, opts :: any) :: String.t() | nil
+
+  @doc """
+  used for unpacking a complex type that requires serialization from one or more form params.
+  For example if your live_form_input routes to a live component that uses a hidden input field containing json that needs
+  to be unpacked before passing to the module's changeset.
+  return params if no special processing required.
+  """
+  @callback hydrate_form_input(key :: atom, params :: Map.t, opts :: any) :: Map.t
+
+
+  @doc """
+  Pass to behavior provider. @see validate_attr!/1
+  """
+  def validate_attr!(provider, attrs) do
+    apply(provider, :validate_attr!, [attrs])
+  end
+
+  @doc """
+  Pass to behavior provider. @see type_and_opts_for_schema/1
+  """
+  def type_and_opts_for_schema(provider, opts) do
+    apply(provider, :type_and_opts_for_schema, [opts])
+  end
+
+  @doc """
+  Pass to behavior provider. @see type_for_migration/1
+  """
+  def type_for_migration(provider, opts) do
+    apply(provider, :type_for_migration, [opts])
+  end
+
+  @doc """
+  Pass to behavior provider. @see `type_to_default/3`
+  """
+  def type_to_default(provider, key, opts, action) do
+    apply(provider, :type_to_default, [key, opts, action])
+  end
+
+  @doc """
+  Pass to behavior provider. @see live_form_input/2
+  """
+  def live_form_input(provider, key, opts) do
+    apply(provider, :live_form_input, [key, opts])
+  end
+end
diff --git a/lib/mix/phoenix/schema.ex b/lib/mix/phoenix/schema.ex
index f77af333c2..528863e9a3 100644
--- a/lib/mix/phoenix/schema.ex
+++ b/lib/mix/phoenix/schema.ex
@@ -247,6 +247,7 @@ defmodule Mix.Phoenix.Schema do
   end
 
   def type_for_migration({:enum, _}), do: :string
+  def type_for_migration({:custom, provider, opts}), do: Mix.Phoenix.CustomGeneratorBehaviour.type_for_migration(provider, opts)
   def type_for_migration(other), do: other
 
   def format_fields_for_schema(schema) do
@@ -265,7 +266,7 @@ defmodule Mix.Phoenix.Schema do
 
   def type_and_opts_for_schema({:enum, opts}),
     do: ~s|Ecto.Enum, values: #{inspect(Keyword.get(opts, :values))}|
-
+  def type_and_opts_for_schema({:custom, provider, opts}), do: Mix.Phoenix.CustomGeneratorBehaviour.type_and_opts_for_schema(provider, opts)
   def type_and_opts_for_schema(other), do: inspect(other)
 
   def maybe_redact_field(true), do: ", redact: true"
@@ -352,6 +353,9 @@ defmodule Mix.Phoenix.Schema do
       :naive_datetime_usec ->
         NaiveDateTime.add(build_utc_naive_datetime_usec(), -@one_day_in_seconds)
 
+      {:custom, provider, opts} ->
+        Mix.Phoenix.CustomGeneratorBehaviour.type_to_default(provider, key, opts, :create)
+
       _ ->
         "some #{key}"
     end
@@ -375,6 +379,8 @@ defmodule Mix.Phoenix.Schema do
       :utc_datetime_usec -> build_utc_datetime_usec()
       :naive_datetime -> build_utc_naive_datetime()
       :naive_datetime_usec -> build_utc_naive_datetime_usec()
+      {:custom, provider, opts} ->
+        Mix.Phoenix.CustomGeneratorBehaviour.type_to_default(provider, key, opts, :update)
       _ -> "some updated #{key}"
     end
   end
@@ -436,12 +442,21 @@ defmodule Mix.Phoenix.Schema do
   defp validate_attr!({_name, type} = attr) when type in @valid_types, do: attr
   defp validate_attr!({_name, {:enum, _vals}} = attr), do: attr
   defp validate_attr!({_name, {type, _}} = attr) when type in @valid_types, do: attr
-
-  defp validate_attr!({_, type}) do
-    Mix.raise(
-      "Unknown type `#{inspect(type)}` given to generator. " <>
-        "The supported types are: #{@valid_types |> Enum.sort() |> Enum.join(", ")}"
-    )
+  defp validate_attr!({name, {type, opts}}) do
+    if Kernel.function_exported?(:"Elixir.#{type}", :validate_attr!, 1) do
+      Mix.Phoenix.CustomGeneratorBehaviour.validate_attr!(:"Elixir.#{type}", {name, :"Elixir.#{type}", opts})
+    else
+      Mix.raise("Unknown type `#{inspect(type)}` given to generator. " <>
+                "The supported types are: #{@valid_types |> Enum.sort() |> Enum.join(", ")}")
+    end
+  end
+  defp validate_attr!({name, type}) do
+    if Kernel.function_exported?(:"Elixir.#{type}", :validate_attr!, 1) do
+      Mix.Phoenix.CustomGeneratorBehaviour.validate_attr!(:"Elixir.#{type}", {name, :"Elixir.#{type}", []})
+    else
+      Mix.raise("Unknown type `#{inspect(type)}` given to generator. " <>
+                "The supported types are: #{@valid_types |> Enum.sort() |> Enum.join(", ")}")
+    end
   end
 
   defp partition_attrs_and_assocs(schema_module, attrs) do
diff --git a/lib/mix/tasks/phx.gen.live.ex b/lib/mix/tasks/phx.gen.live.ex
index 825b27190a..57e65059aa 100644
--- a/lib/mix/tasks/phx.gen.live.ex
+++ b/lib/mix/tasks/phx.gen.live.ex
@@ -326,9 +326,12 @@ defmodule Mix.Tasks.Phx.Gen.Live do
         />
         """
 
+      {key, {:custom, provider, opts}} ->
+        Mix.Phoenix.CustomGeneratorBehaviour.live_form_input(provider, key, opts)
+
       {key, _} ->
         ~s(<.input field={@form[#{inspect(key)}]} type="text" label="#{label(key)}" />)
-    end)
+    end) |> Enum.reject(&is_nil/1)
   end
 
   defp default_options({:array, :string}),
diff --git a/priv/templates/phx.gen.live/form_component.ex b/priv/templates/phx.gen.live/form_component.ex
index 52cf6e85b4..65fb8509a1 100644
--- a/priv/templates/phx.gen.live/form_component.ex
+++ b/priv/templates/phx.gen.live/form_component.ex
@@ -40,6 +40,18 @@ defmodule <%= inspect context.web_module %>.<%= inspect Module.concat(schema.web
 
   @impl true
   def handle_event("validate", %{"<%= schema.singular %>" => <%= schema.singular %>_params}, socket) do
+    <%=
+    Enum.filter(schema.types,
+        fn
+          {_, {:custom, _, _}} -> true
+          _ -> false
+        end)
+    |> Enum.map_join("\n    ",
+        fn
+           {key, {:custom, provider, opts}} ->
+                   "#{ schema.singular }_params = #{inspect provider}.hydrate_form_input(#{inspect key}, #{ schema.singular }_params, #{inspect opts, limit: :infinity})"
+        end)
+    %>
     changeset =
       socket.assigns.<%= schema.singular %>
       |> <%= inspect context.alias %>.change_<%= schema.singular %>(<%= schema.singular %>_params)
@@ -49,6 +61,18 @@ defmodule <%= inspect context.web_module %>.<%= inspect Module.concat(schema.web
   end
 
   def handle_event("save", %{"<%= schema.singular %>" => <%= schema.singular %>_params}, socket) do
+    <%=
+    Enum.filter(schema.types,
+        fn
+          {_, {:custom, _, _}} -> true
+          _ -> false
+        end)
+    |> Enum.map_join("\n    ",
+        fn
+           {key, {:custom, provider, opts}} ->
+                   "#{ schema.singular }_params = #{inspect provider}.hydrate_form_input(#{inspect key}, #{ schema.singular }_params, #{inspect opts, limit: :infinity})"
+        end)
+    %>
     save_<%= schema.singular %>(socket, socket.assigns.action, <%= schema.singular %>_params)
   end
 
diff --git a/test/mix/tasks/phx.gen.live_test.exs b/test/mix/tasks/phx.gen.live_test.exs
index 20108f396d..dc5e046d73 100644
--- a/test/mix/tasks/phx.gen.live_test.exs
+++ b/test/mix/tasks/phx.gen.live_test.exs
@@ -1,10 +1,38 @@
 Code.require_file "../../../installer/test/mix_helper.exs", __DIR__
 
+
+defmodule Phoenix.Test.LiveCustomGen do
+  @behaviour Mix.Phoenix.CustomGeneratorBehaviour
+  def validate_attr!({name, __MODULE__, opts}) do
+    {name, {:custom, __MODULE__, opts}}
+  end
+  def type_and_opts_for_schema(_opts) do
+    ~s|:custom_schema_type|
+  end
+  def type_for_migration(_opts) do
+    :custom_ecto_type
+  end
+  def type_to_default(key, _opts, :create) do
+    "Special #{key}"
+  end
+  def type_to_default(key, _opts, :update) do
+    "Special Updated #{key}"
+  end
+  def live_form_input(key, _opts) do
+    "[SPECIAL INPUT HANDLER: #{key}]"
+  end
+  def hydrate_form_input(_key, params, _opts), do: params
+end
+
+
 defmodule Mix.Tasks.Phx.Gen.LiveTest do
   use ExUnit.Case
   import MixHelper
   alias Mix.Tasks.Phx.Gen
 
+  @moduletag feature: :gen
+  @moduletag gen: :live
+
   setup do
     Mix.Task.clear()
     :ok
@@ -29,6 +57,142 @@ defmodule Mix.Tasks.Phx.Gen.LiveTest do
     end)
   end
 
+
+  describe "custom schema generator support" do
+    test "generate", config  do
+      in_tmp_live_project config.test, fn ->
+        Gen.Live.run(~w(Blog Post posts title:Phoenix.Test.LiveCustomGen slug:unique votes:integer cost:decimal
+                      tags:array:text popular:boolean drafted_at:datetime
+                      status:enum:unpublished:published:deleted
+                      published_at:utc_datetime
+                      published_at_usec:utc_datetime_usec
+                      deleted_at:naive_datetime
+                      deleted_at_usec:naive_datetime_usec
+                      alarm:time
+                      alarm_usec:time_usec
+                      secret:uuid:redact announcement_date:date alarm:time
+                      metadata:map
+                      weight:float user_id:references:users))
+
+        assert_file "lib/phoenix/blog/post.ex"
+        assert_file "lib/phoenix/blog.ex"
+        assert_file "test/phoenix/blog_test.exs"
+
+        assert_file "lib/phoenix_web/live/post_live/index.ex", fn file ->
+          assert file =~ "defmodule PhoenixWeb.PostLive.Index"
+        end
+
+        assert_file "lib/phoenix_web/live/post_live/show.ex", fn file ->
+          assert file =~ "defmodule PhoenixWeb.PostLive.Show"
+        end
+
+        assert_file "lib/phoenix_web/live/post_live/form_component.ex", fn file ->
+          assert file =~ "defmodule PhoenixWeb.PostLive.FormComponent"
+        end
+
+        assert [path] = Path.wildcard("priv/repo/migrations/*_create_posts.exs")
+        assert_file path, fn file ->
+          assert file =~ "create table(:posts)"
+          assert file =~ "add :title, :custom_ecto_type"
+          assert file =~ "create unique_index(:posts, [:slug])"
+        end
+
+        assert_file "lib/phoenix_web/live/post_live/index.html.heex", fn file ->
+          assert file =~ ~S|~p"/posts"|
+        end
+
+        assert_file "lib/phoenix_web/live/post_live/show.html.heex", fn file ->
+          assert file =~ ~S|~p"/posts"|
+        end
+
+        assert_file "lib/phoenix_web/live/post_live/form_component.ex", fn file ->
+          assert file =~ ~s(<.simple_form)
+          assert file =~ ~s([SPECIAL INPUT HANDLER: title])
+          assert file =~ ~s(<.input field={@form[:votes]} type="number")
+          assert file =~ ~s(<.input field={@form[:cost]} type="number" label="Cost" step="any")
+          assert file =~ """
+                         <.input
+                           field={@form[:tags]}
+                           type="select"
+                           multiple
+                 """
+          assert file =~ ~s(<.input field={@form[:popular]} type="checkbox")
+          assert file =~ ~s(<.input field={@form[:drafted_at]} type="datetime-local")
+          assert file =~ ~s(<.input field={@form[:published_at]} type="datetime-local")
+          assert file =~ ~s(<.input field={@form[:deleted_at]} type="datetime-local")
+          assert file =~ ~s(<.input field={@form[:announcement_date]} type="date")
+          assert file =~ ~s(<.input field={@form[:alarm]} type="time")
+          assert file =~ ~s(<.input field={@form[:secret]} type="text" label="Secret" />)
+          refute file =~ ~s(<field={@form[:metadata]})
+          assert file =~ """
+                         <.input
+                           field={@form[:status]}
+                           type="select"
+                 """
+          assert file =~ ~s|Ecto.Enum.values(Phoenix.Blog.Post, :status)|
+
+          assert file =~ ~s|post_params = Phoenix.Test.LiveCustomGen.hydrate_form_input(:title, post_params, [])|
+
+          refute file =~ ~s(<.input field={@form[:user_id]})
+        end
+
+        assert_file "test/phoenix_web/live/post_live_test.exs", fn file ->
+          assert file =~ ~r"@invalid_attrs.*popular: false"
+          assert file =~ ~S|~p"/posts"|
+          assert file =~ ~S|~p"/posts/new"|
+          assert file =~ ~S|~p"/posts/#{post}"|
+          assert file =~ ~S|~p"/posts/#{post}/show/edit"|
+        end
+
+        send self(), {:mix_shell_input, :yes?, true}
+        Gen.Live.run(~w(Blog Comment comments title:string))
+        assert_received {:mix_shell, :info, ["You are generating into an existing context" <> _]}
+
+        assert_file "lib/phoenix/blog/comment.ex"
+        assert_file "test/phoenix_web/live/comment_live_test.exs", fn file ->
+          assert file =~ "defmodule PhoenixWeb.CommentLiveTest"
+        end
+
+        assert [path] = Path.wildcard("priv/repo/migrations/*_create_comments.exs")
+        assert_file path, fn file ->
+          assert file =~ "create table(:comments)"
+          assert file =~ "add :title, :string"
+        end
+
+        assert_file "lib/phoenix_web/live/comment_live/index.ex", fn file ->
+          assert file =~ "defmodule PhoenixWeb.CommentLive.Index"
+        end
+
+        assert_file "lib/phoenix_web/live/comment_live/show.ex", fn file ->
+          assert file =~ "defmodule PhoenixWeb.CommentLive.Show"
+        end
+
+        assert_file "lib/phoenix_web/live/comment_live/form_component.ex", fn file ->
+          assert file =~ "defmodule PhoenixWeb.CommentLive.FormComponent"
+        end
+
+        assert_receive {:mix_shell, :info, ["""
+
+        Add the live routes to your browser scope in lib/phoenix_web/router.ex:
+
+            live "/comments", CommentLive.Index, :index
+            live "/comments/new", CommentLive.Index, :new
+            live "/comments/:id/edit", CommentLive.Index, :edit
+
+            live "/comments/:id", CommentLive.Show, :show
+            live "/comments/:id/show/edit", CommentLive.Show, :edit
+        """]}
+
+        assert_receive({:mix_shell, :info, ["""
+
+        You must update :phoenix_live_view to v0.18 or later and
+        :phoenix_live_dashboard to v0.7 or later to use the features
+        in this generator.
+        """]})
+      end
+    end
+  end
+
   test "invalid mix arguments", config do
     in_tmp_live_project config.test, fn ->
       assert_raise Mix.Error, ~r/Expected the context, "blog", to be a valid module name/, fn ->
diff --git a/test/mix/tasks/phx.gen.schema_test.exs b/test/mix/tasks/phx.gen.schema_test.exs
index ea267f9274..feed83b7b5 100644
--- a/test/mix/tasks/phx.gen.schema_test.exs
+++ b/test/mix/tasks/phx.gen.schema_test.exs
@@ -3,17 +3,89 @@ Code.require_file "../../../installer/test/mix_helper.exs", __DIR__
 defmodule Phoenix.DupSchema do
 end
 
+defmodule Phoenix.Test.CustomGen do
+  @behaviour Mix.Phoenix.CustomGeneratorBehaviour
+  def validate_attr!({name, __MODULE__, opts}) do
+    {name, {:custom, __MODULE__, opts}}
+  end
+  def type_and_opts_for_schema(_opts) do
+    ~s|:custom_schema_type|
+  end
+  def type_for_migration(_opts) do
+    :custom_ecto_type
+  end
+  def type_to_default(key, _opts, :create) do
+    "Special #{key}"
+  end
+  def type_to_default(key, _opts, :update) do
+    "Special Updated #{key}"
+  end
+  def live_form_input(key, _opts) do
+    "[SPECIAL INPUT HANDLER: #{key}]"
+  end
+  def hydrate_form_input(_key, params, _opts), do: params
+end
+
 defmodule Mix.Tasks.Phx.Gen.SchemaTest do
   use ExUnit.Case
   import MixHelper
   alias Mix.Tasks.Phx.Gen
   alias Mix.Phoenix.Schema
 
+  @moduletag feature: :gen
+  @moduletag gen: :schema
+
   setup do
     Mix.Task.clear()
     :ok
   end
 
+  describe "custom schema generator support" do
+
+
+    test "build with custom gen extension" do
+      in_tmp_project "build", fn ->
+        schema = Gen.Schema.build(~w(Blog.Post posts title:Phoenix.Test.CustomGen:option:list tags:map), [])
+
+        assert %Schema{
+                 alias: Post,
+                 module: Phoenix.Blog.Post,
+                 repo: Phoenix.Repo,
+                 migration?: true,
+                 migration_defaults: %{title: ""},
+                 plural: "posts",
+                 singular: "post",
+                 human_plural: "Posts",
+                 human_singular: "Post",
+                 attrs: [title: {:custom, Phoenix.Test.CustomGen, :"option:list"}, tags: :map],
+                 types: %{title: {:custom, Phoenix.Test.CustomGen, :"option:list"}, tags: :map},
+                 optionals: [:tags],
+                 route_helper: "post",
+                 defaults: %{title: "", tags: ""},
+               } = schema
+        assert String.ends_with?(schema.file, "lib/phoenix/blog/post.ex")
+      end
+    end
+
+    test "generates schema with custom gen extension", config do
+      in_tmp_project config.test, fn ->
+        Gen.Schema.run(~w(Blog.CustomPost custom_blog_posts title:Phoenix.Test.CustomGen))
+
+        assert [migration] = Path.wildcard("priv/repo/migrations/*_create_custom_blog_posts.exs")
+        assert_file migration, fn file ->
+          assert file =~ "defmodule Phoenix.Repo.Migrations.CreateCustomBlogPosts do"
+          assert file =~ "create table(:custom_blog_posts) do"
+          assert file =~ "add :title, :custom_ecto_type"
+        end
+
+        assert_file "lib/phoenix/blog/custom_post.ex", fn file ->
+          assert file =~ "defmodule Phoenix.Blog.CustomPost do"
+          assert file =~ "field :title, :custom_schema_type"
+        end
+      end
+    end
+  end
+
   test "build" do
     in_tmp_project "build", fn ->
       schema = Gen.Schema.build(~w(Blog.Post posts title:string tags:map), [])