Zig

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
    }
}

Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    const json = try chilkat.JsonObject.init();
    defer json.deinit();

    // 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.
    const json_str = "{\"name\": \"donut\",\"image\":{\"fname\": \"donut.jpg\",\"w\": 200,\"h\": 200},\"thumbnail\":{\"fname\": \"donutThumb.jpg\",\"w\": 32,\"h\": 32}}";

    json.load(json_str) catch {
        std.debug.print("{s}\n", .{try json.getLastErrorText(alloc)});
        return;
    };

    // The top-level JSON object has three members: name, image, and thumbnail.
    const name_index = json.indexOf("name");
    // The index of the "name" member is 0.
    std.debug.print("nameIndex = {d}\n", .{name_index});

    const thumb_index = json.indexOf("thumbnail");
    // The index of the "thumbnail" member is 2.
    std.debug.print("thumbIndex = {d}\n", .{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).
    var fname_index: i32 = json.indexOf("fname");
    // The fnameIndex is -1 (not found).  This is correct.
    std.debug.print("fnameIndex = {d}\n", .{fname_index});

    // Get the "image" object.
    const image_obj = try chilkat.JsonObject.init();
    defer image_obj.deinit();
    json.objectOf2("image", image_obj) catch {};

    // Now we can get the index of the "fname" object, because it is a direct
    // member of the "image" object:
    fname_index = image_obj.indexOf("fname");
    std.debug.print("fnameIndex = {d}\n", .{fname_index});
}