I recently started learning golang and Revel. Im trying to understand what exactly the below if statement does. Seems like it is doing a type check, but i dont see what the conditional achieves. Appreciate if anyone can tell me whats happening here. thanks
if str, ok := obj.(string); ok {
return len(str) > 0
}
It tries to convert obj (which is of some abstract interface probably) into a string, checks if that worked, and only enters if it turned out okay.
Written more sparsely it can be viewed as:
// do a type assertion/conversion of obj to a string.
// If obj isn't really a string, ok will be false
str, ok := obj.(string)
// this will only run if we're talking about a string
if ok {
return len(str) > 0
}
What go does is safe casting from some interface to the real type. If you do this without the ok part, your program will panic if obj isn't a string. i.e this code will crash your program if obj isn't a string:
str := obj.(string)
return len(str) > 0
You can read more about type assertions in the docs: