Demand in the development of a file upload today, when I select files to upload the file and click save after front-end console to quote an Uncaught TypeError: always read the property 'carid of null error, this demand has two tables, one for the vehicle information table, a picture for the vehicle information table, the vehicle information form the primary key of the vehicle number (id) corresponding to the vehicle images form the vehicle number (carid), when I was in the new vehicle information crosses to upload pictures on the picture below and then click the save picture save success, vehicle number in vehicle table now (carid) and vehicle information table of the vehicle number (id) have done a foreign key relationships, but has been submitted to the carid is empty this exception, teach bosses,