Rust

JSON Paths

See more JSON Examples

Demonstrates using "Chilkat JSON Paths" to access parts of a JSON document, or to iterate over parts.

This example uses the following JSON document:

{
    "nestedArray" : [
			[
				[1,2,3],
				[4,5,6],
				[7,8,9,10]
			],
			[
				[11,12,13],
				[14,15,16],
				[17,18,19,20]
			],
			[
				[21,22,23],
				[24,25,26],
				[27,28,29,30],
				[31,32,33,34,35,36]
			]
		],

	"nestedObject" : {
		"aaa" : {
			"bb1" : {
				"cc1" : "c1Value",
				"cc2" : "c2Value",
				"cc3" : "c3Value"
			},
			"bb2" : {
				"dd1" : "d1Value",
				"dd2" : "d2Value",
				"dd3" : "d3Value"
			}
		}
	},

	"mixture" : {
		"arrayA" : [  
			{ "fruit": "apple", "animal": "horse", "job": "fireman", "colors": ["red","blue","green"] },
			{ "fruit": "pear", "animal": "plankton", "job": "waiter", "colors": ["yellow","orange","purple"] },
			{ "fruit": "kiwi", "animal": "echidna", "job": "astronaut", "colors": ["magenta","tan","pink"] }
			]
	},


        "name.with.dots" : { "grain" : "oats" }

	
}

Rust

let json = chilkat::JsonObject::new();
json.set_emit_compact(false);

// Assume the file contains the data as shown above..
if json.load_file("qa_data/json/pathSample.json").is_err() {
    println!("{}", json.last_error_text());
    return;
}

// First, let's get the value of "cc1"
// The path to this value is: nestedObject.aaa.bb1.cc1
println!("{}", json.string_of("nestedObject.aaa.bb1.cc1").unwrap_or_default());

// Now let's get number 18 from the nestedArray.
// It is located at nestedArray[1][2][1]
// (remember: Indexing is 0-based)
println!("This should be 18: {}", json.int_of("nestedArray[1][2][1]"));

// We can do the same thing in a more roundabout way using the 
// I, J, and K properties.  (The I,J,K properties will be convenient
// for iterating over arrays, as we'll see later.)
json.set_i(1);
json.set_j(2);
json.set_k(1);
println!("This should be 18: {}", json.int_of("nestedArray[i][j][k]"));

// Let's iterate over the array containing the numbers 17, 18, 19, 20.
// First, use the SizeOfArray method to get the array size:
let sz = json.size_of_array("nestedArray[1][2]");
// The size should be 4.
println!("size of array = {} (should equal 4)", sz);

// Now iterate...
for i in 0..sz {
    json.set_i(i);
    println!("{}", json.int_of("nestedArray[1][2][i]"));
}

// Let's use a triple-nested loop to iterate over the nestedArray:

// szI should equal 1.
let sz_i = json.size_of_array("nestedArray");
for i in 0..sz_i {
    json.set_i(i);

    let sz_j = json.size_of_array("nestedArray[i]");
    for j in 0..sz_j {
        json.set_j(j);

        let sz_k = json.size_of_array("nestedArray[i][j]");
        for k in 0..sz_k {
            json.set_k(k);

            println!("{}", json.int_of("nestedArray[i][j][k]"));
        }

    }

}

// Now let's examine how to navigate to JSON objects contained within JSON arrays.
// This line of code gets the value "kiwi" contained within "mixture"
println!("{}", json.string_of("mixture.arrayA[2].fruit").unwrap_or_default());

// This line of code gets the color "yellow"
println!("{}", json.string_of("mixture.arrayA[1].colors[0]").unwrap_or_default());

// Getting an object at a path:
// This gets the 2nd object in "arrayA"

let obj2 = chilkat::JsonObject::new();
let _ = json.object_of2("mixture.arrayA[1]", &obj2);

// This object's "animal" should be "plankton"
println!("{}", obj2.string_of("animal").unwrap_or_default());

// Note that paths are relative to the object, not the absolute root of the JSON document.
// Starting from obj2, "purple" is at "colors[2]"
println!("{}", obj2.string_of("colors[2]").unwrap_or_default());

// Getting an array at a path:
// This gets the array containing the colors red, green, blue:

let arr1 = chilkat::JsonArray::new();
let _ = json.array_of2("mixture.arrayA[0].colors", &arr1);

let sz_arr1 = arr1.size();
for i in 0..sz_arr1 {
    println!("{}: {}", i, arr1.string_at(i).unwrap_or_default());
}

// The Chilkat JSON path uses ".", "[", and "]" chars for separators.  When a name
// contains one of these chars, use double-quotes in the path:
println!("{}", json.string_of("\"name.with.dots\".grain").unwrap_or_default());