From 8f2f221b4fc4d82f5c2d633d228b1b1cfffc972c Mon Sep 17 00:00:00 2001
From: yunmikun <a.paramonenko@elonsoft.ru>
Date: Wed, 17 Jun 2020 13:32:47 +0300
Subject: [PATCH] Add base64-encoded images support

When casting an image in base64-encoded format it will be casted to a
binary image with generated file name.
---
 lib/waffle_ecto/schema.ex | 17 +++++++++++++++++
 test/schema_test.exs      | 12 ++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/lib/waffle_ecto/schema.ex b/lib/waffle_ecto/schema.ex
index 5c7f7d0..c7077ce 100644
--- a/lib/waffle_ecto/schema.ex
+++ b/lib/waffle_ecto/schema.ex
@@ -104,6 +104,18 @@ defmodule Waffle.Ecto.Schema do
       when is_binary(filename) and is_binary(binary) ->
         [{field, {upload, scope}} | fields]
 
+      {field, data = "data:image/" <> _}, fields ->
+        encoded_image = String.replace(data, ~r/^data\:image\/.*;base64,/, "")
+
+        case Base.decode64(encoded_image) do
+          {:ok, binary_image} ->
+            upload = %{filename: unique_file_name(data), binary: binary_image}
+            [{field, {upload, scope}} | fields]
+
+          _ ->
+            fields
+        end
+
       # If casting a binary (path), ensure we've explicitly allowed paths
       {field, path}, fields when is_binary(path) ->
         path = String.trim(path)
@@ -124,6 +136,11 @@ defmodule Waffle.Ecto.Schema do
     end)
   end
 
+  defp unique_file_name("data:image/" <> rest) do
+    extension = String.replace(rest, ~r/;base64,.*/, "")
+    "#{Ecto.UUID.generate()}.#{extension}"
+  end
+
   def convert_params_to_binary(params) do
     Enum.reduce(params, nil, fn
       {key, _value}, nil when is_binary(key) ->
diff --git a/test/schema_test.exs b/test/schema_test.exs
index 8211036..03bb818 100644
--- a/test/schema_test.exs
+++ b/test/schema_test.exs
@@ -175,4 +175,16 @@ defmodule WaffleTest.Ecto.Schema do
              )
            )
   end
+
+  test_with_mock "casting base64-encoded data struct attachments", DummyDefinition,
+    store: fn {%{filename: _, binary: _}, %TestUser{}} ->
+      {:ok, "file.png"}
+    end do
+    cs = TestUser.changeset(%TestUser{}, %{
+      "avatar" => "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg=="
+    })
+
+    assert cs.valid?
+    assert %{avatar: %{file_name: "file.png", updated_at: _}} = cs.changes
+  end
 end