Rust

Get the Index of a JSON Member

See more JSON Examples

This example demonstrates how to get the index of a given member by name.

{
  "name": "donut",
  "image":
    {
    "fname": "donut.jpg",
    "w": 200,
    "h": 200
    },
  "thumbnail":
    {
    "fname": "donutThumb.jpg",
    "w": 32,
    "h": 32
    }
}

Rust

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

// This is the above JSON with whitespace chars removed (SPACE, TAB, CR, and LF chars).
// The presence of whitespace chars for pretty-printing makes no difference to the Load
// method. 
let json_str = "{\"name\": \"donut\",\"image\":{\"fname\": \"donut.jpg\",\"w\": 200,\"h\": 200},\"thumbnail\":{\"fname\": \"donutThumb.jpg\",\"w\": 32,\"h\": 32}}".to_string();

if json.load(&json_str).is_err() {
    println!("{}", json.last_error_text());
    return;
}

// The top-level JSON object has three members: name, image, and thumbnail.
let name_index = json.index_of("name");
// The index of the "name" member is 0.
println!("nameIndex = {}", name_index);

let thumb_index = json.index_of("thumbnail");
// The index of the "thumbnail" member is 2.
println!("thumbIndex = {}", thumb_index);

// The "fname" member is NOT a direct member of the top-level JSON object.
// It is a member of a nested object.  If we try to get the index of this
// member using the top-level JSON object, it is not found (and returns -1).
let mut fname_index = json.index_of("fname");
// The fnameIndex is -1 (not found).  This is correct.
println!("fnameIndex = {}", fname_index);

// Get the "image" object.
let image_obj = chilkat::JsonObject::new();
let _ = json.object_of2("image", &image_obj);

// Now we can get the index of the "fname" object, because it is a direct
// member of the "image" object:
fname_index = image_obj.index_of("fname");
println!("fnameIndex = {}", fname_index);