llJsonGetValue

string llJsonGetValue(string JSON, list Specifiers)

Gets the value indicated by Specifiers from the JSON string.

Parameters

JSON (string)
Specifiers (list)

Technical Details

Return Type: string
Energy: 10

Basic Key-Value Lookup

default {
    state_entry() {
        // Example of a JSON string with a key called "key" and value "val"
        string json1 = "{\"key\":\"val\"}";
        llSay(0, llJsonGetValue(json1, ["key"])); // returns "val" in localchat

        string json2 = "{\"mansBestFriend\":\"dog\"}";
        llSay(0, llJsonGetValue(json2, ["mansBestFriend"])); // returns "dog" in localchat
    }
}

Accessing Arrays and Nested Data

JGetValTest() {
    string j = "[[1,2],[4,5,6]]"; // JSON may be written directly as a string like this in SL

    // Returns the whole array as a JSON string
    string k = llJsonGetValue(j, []);

    // Get first element (index 0)
    k = llJsonGetValue(j, [0]); // returns "[1,2]"

    // Get second element (index 1)
    k = llJsonGetValue(j, [1]); // returns "[4,5,6]"

    // Access nested elements using chained specifiers
    k = llJsonGetValue(j, [1, 2]); // returns "6" (third element of second sub-array)

    // JSON primitives and type conversion
    k = llJsonGetValue("\"3.14\"", []); // returns "3.14" (string value from JSON_STRING)
    k = llJsonGetValue("true", []); // returns JSON_TRUE (lowercase "true" is valid JSON boolean)
    k = llJsonGetValue("True", []); // returns JSON_INVALID (uppercase "True" is not valid JSON)
}

Caveats

Manual definition of JSON syntax within LSL does not always parse as expected. Be careful to avoid using syntax characters anywhere other than where needed (for example, inside a string). Alternatively, escape the syntax character and use llUnescapeURL on the retrieved string to convert it back.
When the input is invalid or no result can be found, this function returns JSON_INVALID. If the result is null, the function returns JSON_NULL.
The function will convert the occurrence of \n to a line feed and \t to U+0009.
Performance note: As of Second Life Server 2024-06-11, llJsonGetValue takes approximately 2-3 ms per call regardless of depth, making it faster for reading a single element. However, llParseStringKeepNulls (5 ms) plus llList2String (0.5 ms per element) is faster when reading multiple elements from a dataset.

Known Issues

JSON does not correctly handle ] inside strings nested within arrays or } inside strings nested within objects (BUG-6495)

llJsonGetValue

Basic Key-Value Lookup

Accessing Arrays and Nested Data

Caveats

Known Issues

See Also