After obtaining the database data in thinkPHP5, the value of the drop-down box is selected by default and is passed to the background and disappears. There are pictures and codes, I hope someone can help.

Question

After getting the data from the database, it is selected by default and I write it in two formats:

The ajax method is used ：

If I write a judgment statement, when I change the option of the drop-down box and submit it, js can get the changed data, which is the value of status and role:

The following picture is the background code (part):

%

Answer 1

I see!

Empty defaults to 0==null, so it cannot be stored in the data array after changing it to 0. There is naturally no status value in data

Answer 2

My status clearly has a value, why is it judged as empty by empty?