assemblyscript-json
JSON encoder / decoder for AssemblyScript.
Special thanks to https://github.com/MaxGraey/bignum.wasm for basic unit testing infra for AssemblyScript.
Installation
assemblyscript-json
is available as a npm package. You can install assemblyscript-json
in your AssemblyScript project by running:
npm install --save assemblyscript-json
Usage
Parsing JSON
import { JSON } from "assemblyscript-json";
// Parse an object using the JSON object
let jsonObj: JSON.Obj = <JSON.Obj>(JSON.parse('{"hello": "world", "value": 24}'));
// We can then use the .getX functions to read from the object if you know it's type
// This will return the appropriate JSON.X value if the key exists, or null if the key does not exist
let worldOrNull: JSON.Str | null = jsonObj.getString("hello"); // This will return a JSON.Str or null
if (worldOrNull != null) {
// use .valueOf() to turn the high level JSON.Str type into a string
let world: string = worldOrNull.valueOf();
}
let numOrNull: JSON.Num | null = jsonObj.getNum("value");
if (numOrNull != null) {
// use .valueOf() to turn the high level JSON.Num type into a f64
let value: f64 = numOrNull.valueOf();
}
// If you don't know the value type, get the parent JSON.Value
let valueOrNull: JSON.Value | null = jsonObj.getValue("hello");
if (valueOrNull != null) {
let value = <JSON.Value>valueOrNull;
// Next we could figure out what type we are
if(value.isString) {
// value.isString would be true, so we can cast to a string
let innerString = (<JSON.Str>value).valueOf();
let jsonString = (<JSON.Str>value).stringify();
// Do something with string value
}
}
Encoding JSON
import { JSONEncoder } from "assemblyscript-json";
// Create encoder
let encoder = new JSONEncoder();
// Construct necessary object
encoder.pushObject("obj");
encoder.setInteger("int", 10);
encoder.setString("str", "");
encoder.popObject();
// Get serialized data
let json: Uint8Array = encoder.serialize();
// Or get serialized data as string
let jsonString: string = encoder.stringify();
assert(jsonString, '"obj": {"int": 10, "str": ""}'); // True!
Custom JSON Deserializers
import { JSONDecoder, JSONHandler } from "assemblyscript-json";
// Events need to be received by custom object extending JSONHandler.
// NOTE: All methods are optional to implement.
class MyJSONEventsHandler extends JSONHandler {
setString(name: string, value: string): void {
// Handle field
}
setBoolean(name: string, value: bool): void {
// Handle field
}
setNull(name: string): void {
// Handle field
}
setInteger(name: string, value: i64): void {
// Handle field
}
setFloat(name: string, value: f64): void {
// Handle field
}
pushArray(name: string): bool {
// Handle array start
// true means that nested object needs to be traversed, false otherwise
// Note that returning false means JSONDecoder.startIndex need to be updated by handler
return true;
}
popArray(): void {
// Handle array end
}
pushObject(name: string): bool {
// Handle object start
// true means that nested object needs to be traversed, false otherwise
// Note that returning false means JSONDecoder.startIndex need to be updated by handler
return true;
}
popObject(): void {
// Handle object end
}
}
// Create decoder
let decoder = new JSONDecoder<MyJSONEventsHandler>(new MyJSONEventsHandler());
// Create a byte buffer of our JSON. NOTE: Deserializers work on UTF8 string buffers.
let jsonString = '{"hello": "world"}';
let jsonBuffer = Uint8Array.wrap(String.UTF8.encode(jsonString));
// Parse JSON
decoder.deserialize(jsonBuffer); // This will send events to MyJSONEventsHandler
Feel free to look through the tests for more usage examples.
Reference Documentation
Reference API Documentation can be found in the docs directory.