Rust

Check if Integer Exists at JSON Path

Demonstrates how to get an integer value at a JSON path, and how to check to see if it exists. Rust

let json = chilkat::JsonObject::new();

// First build simple JSON..
let _ = json.update_int("test.abc", 100);

json.set_emit_compact(false);
println!("{}", json.emit().unwrap_or_default());

// This is our JSON:
// {
//   "test": {
//     "abc": 100,
//   }
// }

let path = "test.notHere".to_string();

// The call to IntOf will return 0, because it's not present.
// But how do we know if it really was present, and the value was truly 0?
let val = json.int_of(&path);
println!("val = {}", val);

// We cannot use LastMethodSuccess because LastMethodSuccess only applies
// to methods that:
// - return a string
// - return a new Chilkat object, binary bytes, or a date/time.
// - returns a boolean status where true = success and false = failed.
// - returns an integer where failure is defined by a return value less than zero.
// The IntOf method fits none of these requirements, and therefore the LastMethodSuccess 
// is not a valid indicator..
let mut was_found = json.last_method_success();
println!("wasFound = {} (not a valid indicator)", was_found);

// Instead, if the returned value is 0, we can double-check to see if the member was truly there..
if val == 0 {
    was_found = json.has_member(&path);
    println!("wasFound = {}", was_found);
    if was_found {
        println!("The value was present and is 0.");
    } else {
        println!("no member is present at test.notHere");
    }

} else {
    println!("val = {}", val);
}

// Alternatively, you could check to see if the member exists beforehand..
if json.has_member(&path) {
    println!("val = {}", json.int_of(&path));
} else {
    println!("no member at {}", path);
}