From 885ab9a01554bf3d23e4b4cb09d1f10e2b72dcf0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Guitaut?= <loic@discourse.org>
Date: Tue, 27 Jun 2023 02:51:58 +0200
Subject: [PATCH] DEV: Introduce an `array` type for Chat contracts (#22278)
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This small patch registers a new `ActiveModel` type: `array`.
It will split a string on `,` to create a new array. If the value is
already an array, nothing will happen and for all other types, it will
wrap the value in an array.

Here’s an example on an existing contract:
```ruby
  attribute :target_usernames

  before_validation do
    self.target_usernames =
      (
        if target_usernames.is_a?(String)
          target_usernames.split(",")
        else
          target_usernames
        end
      )
  end

  # can be rewritten as:

  attribute :target_usernames, :array
```
---
 plugins/chat/lib/chat/types/array.rb          | 20 +++++++++++
 plugins/chat/plugin.rb                        |  2 ++
 .../chat/spec/lib/chat/types/array_spec.rb    | 35 +++++++++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100644 plugins/chat/lib/chat/types/array.rb
 create mode 100644 plugins/chat/spec/lib/chat/types/array_spec.rb

diff --git a/plugins/chat/lib/chat/types/array.rb b/plugins/chat/lib/chat/types/array.rb
new file mode 100644
index 00000000000..2c4672ff1b5
--- /dev/null
+++ b/plugins/chat/lib/chat/types/array.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module Chat
+  module Types
+    class Array < ActiveModel::Type::Value
+      def serializable?(_)
+        false
+      end
+
+      def cast_value(value)
+        case value
+        when String
+          value.split(",")
+        else
+          ::Array.wrap(value)
+        end
+      end
+    end
+  end
+end
diff --git a/plugins/chat/plugin.rb b/plugins/chat/plugin.rb
index 9f797d04800..2f0e17d373e 100644
--- a/plugins/chat/plugin.rb
+++ b/plugins/chat/plugin.rb
@@ -496,6 +496,8 @@ after_initialize do
   )
 
   register_bookmarkable(Chat::MessageBookmarkable)
+
+  ActiveModel::Type.register(:array, Chat::Types::Array)
 end
 
 if Rails.env == "test"
diff --git a/plugins/chat/spec/lib/chat/types/array_spec.rb b/plugins/chat/spec/lib/chat/types/array_spec.rb
new file mode 100644
index 00000000000..c6e843d4a18
--- /dev/null
+++ b/plugins/chat/spec/lib/chat/types/array_spec.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe Chat::Types::Array do
+  subject(:type) { described_class.new }
+
+  describe "#cast" do
+    subject(:casted_value) { type.cast(value) }
+
+    context "when 'value' is a string" do
+      let(:value) { "first,second,third" }
+
+      it "splits it" do
+        expect(casted_value).to eq(%w[first second third])
+      end
+    end
+
+    context "when 'value' is an array" do
+      let(:value) { %w[existing array] }
+
+      it "returns it" do
+        expect(casted_value).to eq(value)
+      end
+    end
+
+    context "when 'value' is something else" do
+      let(:value) { Time.current }
+
+      it "wraps it in a new array" do
+        expect(casted_value).to eq([value])
+      end
+    end
+  end
+end