DEV: Move array type custom fields to JSON type in automation (#26939)

The automation plugin has 4 custom field types that are array typed. However, array typed custom fields are deprecated and should be migrated to JSON type.

This commit does a couple of things:

1. Migrate all four custom fields to JSON
2. Fix a couple of small bugs that have been discovered while migrating the custom fields to JSON (see the comments on this commit's PR for details https://github.com/discourse/discourse/pull/26939)

plugins/automation/db/post_migrate/20240507112651_switch_topic_automation_custom_fields_to_json.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+class SwitchTopicAutomationCustomFieldsToJson < ActiveRecord::Migration[7.0]
+  def up
+    results = DB.query(<<~SQL)
+      SELECT topic_id, ARRAY_AGG(value) AS values
+      FROM topic_custom_fields
+      WHERE name = 'discourse_automation_ids'
+      GROUP BY topic_id
+    SQL
+
+    execute(<<~SQL)
+      DELETE FROM topic_custom_fields
+      WHERE name = 'discourse_automation_ids'
+    SQL
+
+    results.each do |row|
+      parsed = row.values.map(&:to_i).uniq
+
+      DB.exec(<<~SQL, topic_id: row.topic_id, value: parsed.to_json)
+        INSERT INTO topic_custom_fields
+        (topic_id, name, value, created_at, updated_at)
+        VALUES
+        (:topic_id, 'discourse_automation_ids_json', :value, NOW(), NOW())
+      SQL
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

plugins/automation/db/post_migrate/20240507112751_switch_user_automation_custom_fields_to_json.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+class SwitchUserAutomationCustomFieldsToJson < ActiveRecord::Migration[7.0]
+  def up
+    results = DB.query(<<~SQL)
+      SELECT user_id, ARRAY_AGG(value) AS values
+      FROM user_custom_fields
+      WHERE name = 'discourse_automation_ids'
+      GROUP BY user_id
+    SQL
+
+    execute(<<~SQL)
+      DELETE FROM user_custom_fields
+      WHERE name = 'discourse_automation_ids'
+    SQL
+
+    results.each do |row|
+      parsed = row.values.map(&:to_i).uniq
+
+      DB.exec(<<~SQL, user_id: row.user_id, value: parsed.to_json)
+        INSERT INTO user_custom_fields
+        (user_id, name, value, created_at, updated_at)
+        VALUES
+        (:user_id, 'discourse_automation_ids_json', :value, NOW(), NOW())
+      SQL
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

plugins/automation/db/post_migrate/20240507112851_switch_topic_automation_triggered_ids_custom_fields_to_json.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+class SwitchTopicAutomationTriggeredIdsCustomFieldsToJson < ActiveRecord::Migration[7.0]
+  def up
+    results = DB.query(<<~SQL)
+      SELECT topic_id, ARRAY_AGG(value) AS values
+      FROM topic_custom_fields
+      WHERE name = 'auto_responder_triggered_ids'
+      GROUP BY topic_id
+    SQL
+
+    execute(<<~SQL)
+      DELETE FROM topic_custom_fields
+      WHERE name = 'auto_responder_triggered_ids'
+    SQL
+
+    results.each do |row|
+      parsed = row.values.map(&:to_i).uniq
+
+      DB.exec(<<~SQL, topic_id: row.topic_id, value: parsed.to_json)
+        INSERT INTO topic_custom_fields
+        (topic_id, name, value, created_at, updated_at)
+        VALUES
+        (:topic_id, 'auto_responder_triggered_ids_json', :value, NOW(), NOW())
+      SQL
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

plugins/automation/db/post_migrate/20240507112951_drop_automation_ids_custom_field_indexes.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class DropAutomationIdsCustomFieldIndexes < ActiveRecord::Migration[7.0]
+  def change
+    remove_index :topic_custom_fields,
+                 name: :idx_topic_custom_fields_discourse_automation_unique_id_partial,
+                 if_exists: true
+    remove_index :user_custom_fields,
+                 name: :idx_user_custom_fields_discourse_automation_unique_id_partial,
+                 if_exists: true
+    remove_index :post_custom_fields,
+                 name: :idx_post_custom_fields_discourse_automation_unique_id_partial,
+                 if_exists: true
+  end
+end