fix(nocodb): revise convertAttachmentType logic

packages/nocodb/src/lib/db/sql-data-mapper/lib/sql/BaseModelSqlv2.ts

@@ -2737,6 +2737,15 @@ class BaseModelSqlv2 {
       : await this.dbDriver.raw(query);
   }
 
+  private _convertAttachmentType(attachmentColumns, d) {
+    attachmentColumns.forEach((col) => {
+      if (d[col.title] && typeof d[col.title] === 'string') {
+        d[col.title] = JSON.parse(d[col.title]);
+      }
+    });
+    return d;
+  }
+
   private convertAttachmentType(data) {
     // attachment is stored in text and parse in UI
     // convertAttachmentType is used to convert the response in string to array of object in API response
@@ -2745,20 +2754,16 @@ class BaseModelSqlv2 {
         (c) => c.uidt === UITypes.Attachment
       );
       if (attachmentColumns.length) {
-        if (!Array.isArray(data)) {
-          data = [data];
+        if (Array.isArray(data)) {
+          data = data.map((d) =>
+            this._convertAttachmentType(attachmentColumns, d)
+          );
+        } else {
+          this._convertAttachmentType(attachmentColumns, data);
         }
-        data = data.map((d) => {
-          attachmentColumns.forEach((col) => {
-            if (d[col.title] && typeof d[col.title] === 'string') {
-              d[col.title] = JSON.parse(d[col.title]);
-            }
-          });
-          return d;
-        });
       }
     }
-    return data.length === 1 ? data[0] : data;
+    return data;
   }
 }