fix: create locale column when migrating from v4 (#20261)

* fix: create locale column

* fix: typo

* fix: rewrite comment

* feat: create locale column migration

packages/core/database/src/migrations/internal-migrations/5.0.0-03-locale.ts

@@ -0,0 +1,45 @@
+import type { Knex } from 'knex';
+import { isNil } from 'lodash/fp';
+
+import type { Migration } from '../common';
+
+/**
+ * In v4, content types with disabled i18n did not have any locale column.
+ * In v5, we need to add a `locale` column to all content types.
+ * Other downstream migrations will make use of this column.
+ *
+ * This function creates the `locale` column if it doesn't exist.
+ */
+const createLocaleColumn = async (db: Knex, tableName: string) => {
+  await db.schema.alterTable(tableName, (table) => {
+    table.string('locale');
+  });
+};
+
+export const createdLocale: Migration = {
+  name: '5.0.0-03-created-locale',
+  async up(knex, db) {
+    for (const meta of db.metadata.values()) {
+      const hasTable = await knex.schema.hasTable(meta.tableName);
+
+      if (!hasTable) {
+        continue;
+      }
+
+      // Ignore non-content types
+      const uid = meta.uid;
+      const model = strapi.getModel(uid);
+      if (!model) {
+        continue;
+      }
+
+      // Create locale column if it doesn't exist
+      if (isNil(meta.attributes.locale)) {
+        await createLocaleColumn(knex, meta.tableName);
+      }
+    }
+  },
+  async down() {
+    throw new Error('not implemented');
+  },
+};

packages/core/database/src/migrations/internal-migrations/index.ts

@@ -1,6 +1,7 @@
 import type { Migration } from '../common';
 import { createdDocumentId } from './5.0.0-02-document-id';
 import { renameIdentifiersLongerThanMaxLength } from './5.0.0-01-convert-identifiers-long-than-max-length';
+import { createdLocale } from './5.0.0-03-locale';
 
 /**
  * List of all the internal migrations. The array order will be the order in which they are executed.
@@ -14,4 +15,5 @@ import { renameIdentifiersLongerThanMaxLength } from './5.0.0-01-convert-identif
 export const internalMigrations: Migration[] = [
   renameIdentifiersLongerThanMaxLength,
   createdDocumentId,
+  createdLocale,
 ];