Question

So I have learned that when a file is uploaded in Drupal, you get the fid in return, which you can find in the files table in the database. I keep seeing strings that look like the following, and I was hoping someone could explain each part.

a:2:{i:0;s:4:"9201";i:1;s:4:"9206";}

I can see that here the fids are 9201 and 9206, respectively, and I’m assuming the i:0 and i:1 have to do with the order the files were uploaded. But what is the rest of it?

Also, if it matters, this particular string was the result of a print_r from form data with a multi-file upload field.

Answer 1

It’s the return value from PHP’s serialize() function when passed an array equivalent to the following:

array(
  0 => "9201",
  1 => "9206"
)

You can reverse the process using unserialize().

Drupal (like a lot of applications) saves some settings in a serialized string rather than creating database tables for every possible setting.

EDIT

Just to add, a:2 means the type of variable to follow is an array with 2 elements and s:4 means the type of variable is a string with 4 characters. i denotes an integer type.