change mysql datatype column from string to json
Whilst a JSON field may do what you want, consider proper Data Normalisation rules first. 

As soon as you want "more than one" of something, you should be thinking about a new table that contains those multiple instances, with a foreign key back to the table that contained "the one" thing previously. 

select * from vendor_horses ; 

+----+---------+
| id | name    | 
+----+---------+
|  1 | Red Rum |
+----+---------+

select * from vendor_horse_images ; 

+----+-------+-----------------------+
| id | vh_id | path                  | 
+----+-------+-----------------------+
| 22 |     1 | /users/57/user-11.png |
| 33 |     1 | /users/57/user-73.png |
+----+-------+-----------------------+