fixes thechangelog#191: support the avatar upload by an image URL

    This commit will add the support to upload the avatar
    of a person by providing the image URL.
    That feature is available from the admin website.

lib/changelog/arc_ecto/schema.ex

@@ -0,0 +1,75 @@
+defmodule Changelog.Arc.Ecto.Schema do
+  defmacro __using__(_) do
+    quote do
+      import Changelog.Arc.Ecto.Schema
+    end
+  end
+
+  defmacro cast_attachments(changeset_or_data, params, allowed, options \\ []) do
+    quote bind_quoted: [changeset_or_data: changeset_or_data,
+                        params: params,
+                        allowed: allowed,
+                        options: options] do
+
+      # If given a changeset, apply the changes to obtain the underlying data
+      scope = case changeset_or_data do
+        %Ecto.Changeset{} -> Ecto.Changeset.apply_changes(changeset_or_data)
+        %{__meta__: _} -> changeset_or_data
+      end
+
+      # Cast supports both atom and string keys, ensure we're matching on both.
+      allowed = Enum.map(allowed, fn key ->
+        case key do
+          key when is_binary(key) -> key
+          key when is_atom(key) -> Atom.to_string(key)
+        end
+      end)
+
+      arc_params = case params do
+        :invalid ->
+          :invalid
+        %{} ->
+          params
+          |> Changelog.Arc.Ecto.Schema.convert_params_to_binary
+          |> Map.take(allowed)
+          |> Enum.reduce([], fn
+            # Don't wrap nil casts in the scope object
+            {field, nil}, fields -> [{field, nil} | fields]
+
+            # Allow casting Plug.Uploads
+            {field, upload = %{__struct__: Plug.Upload}}, fields -> [{field, {upload, scope}} | fields]
+
+            # If casting a binary (path), ensure we've explicitly allowed paths or urls
+            {field, path}, fields when is_binary(path) ->
+              if Keyword.get(options, :allow_urls, false) and Regex.match?( ~r/^https?:\/\// , path) do
+                [{field, {path, scope}} | fields]
+              else
+                if Keyword.get(options, :allow_paths, false) do
+                  [{field, {path, scope}} | fields]
+                else
+                  fields
+                end
+              end
+          end)
+          |> Enum.into(%{})
+      end
+
+      cast(changeset_or_data, arc_params, allowed)
+    end
+  end
+
+  def convert_params_to_binary(params) do
+    Enum.reduce(params, nil, fn
+      {key, _value}, nil when is_binary(key) ->
+        nil
+
+      {key, _value}, _ when is_binary(key) ->
+        raise ArgumentError, "expected params to be a map with atoms or string keys, " <>
+                             "got a map with mixed keys: #{inspect params}"
+
+      {key, value}, acc when is_atom(key) ->
+        Map.put(acc || %{}, Atom.to_string(key), value)
+
+    end) || params
+  end
+end

lib/changelog/data/data.ex

@@ -4,7 +4,7 @@ defmodule Changelog.Data do
 
     quote do
       use Ecto.Schema
-      use Arc.Ecto.Schema
+      use Changelog.Arc.Ecto.Schema
       use Timex.Ecto.Timestamps
 
       import Ecto

lib/changelog/data/person.ex

@@ -66,7 +66,7 @@ defmodule Changelog.Person do
 
   defp changeset_with_allowed_params(struct, params, allowed) do
     struct
-    |> cast_attachments(params, ~w(avatar))
+    |> cast_attachments(params, ~w(avatar), allow_urls: true)
     |> cast(params, allowed)
     |> validate_required([:name, :email, :handle])
     |> validate_format(:website, Regexp.http, message: Regexp.http_message)

lib/changelog_web/templates/admin/person/_form.html.eex

@@ -51,7 +51,12 @@
       <br/>
     <% end %>
     <%= error_message(f, :avatar) %>
-    <%= file_input f, :avatar %>
+    <div class="field">
+      <%= text_input f, :avatar, placeholder: "Avatar image URL", value: "" %>
+    </div>
+    <div class="field">
+      <%= file_input f, :avatar %>
+    </div>
   </div>
 
   <div class="two fields">

test/changelog/data/person_test.exs

@@ -16,6 +16,17 @@ defmodule Changelog.PersonTest do
     refute changeset.valid?
   end
 
+  test "admin_changeset with a local file path image URL attribute" do
+    person = insert(:person)
+    local_file_path = File.cwd! <> "/test/fixtures/avatar600x600.png"
+    attrs = Map.put(@valid_attrs, :avatar, local_file_path)
+
+    changeset = Person.admin_changeset(person, attrs)
+
+    assert changeset.valid?
+    refute Map.has_key?(changeset.changes, :avatar)
+  end
+
   test "encoded_auth and decoded_auth" do
     user = %Person{email: "[email protected]", auth_token: "8675309"}
     {:ok, encoded} = Person.encoded_auth(user)