Buffers and custom encoding examples

Is there a canonical set of examples for no string encoding and or custom encodings?

The first example I found was https://github.com/Level/levelup/blob/master/test/inject-encoding-test.js but that requires learning about msgpack-js.

Second example I found was https://github.com/Level/levelup/issues/412, which described binary (a string encoding format, aliasing latin1 as per nodejs documentation) somehow returning a Buffer…

I just want to put(keyBuffer, valueBuffer), get(keyBuffer, (err, valueBuffer) => {}) and it isn’t entirely clear how to do that…

At least with a Buffer, I could then just push it through something like https://github.com/dominictarr/varstruct for type checking.

[peakji]

@dcousens the encoding here is actually the codec name of your custom-encoding , which represents a pair of encode and decode functions, and a buffer option. utf8 and binaryare just built-in bidirectional codecs, in fact, theres also one called json.

[peakji]

I just want to put(keyBuffer, valueBuffer), get(keyBuffer, (err, valueBuffer) => {}) and it isn’t entirely clear how to do that…

Set keyEncoding: "binary" and valueEncoding : "binary" in options of any main interface method.

It should probably also document the lifetime of any Buffer passed, since the arguments are not copied-on-use the underlying data committed can change… 😨

We can’t document it in levelup because the lifetime depends on the implementation of storage backend. For the put method in the default leveldown backend, it is handled by database_async.cc#L175, so its not safe to modify buffer values until callback:

db.open(function(err) {
	var buf = Buffer.from([0x00, 0x01, 0x02]);
	db.put("test", buf, {
		valueEncoding: "binary"
	}, function(err) {
		buf[0] = 0x04;
		db.get("test", {
			valueEncoding: "binary"
		}, function(err, val) {
			console.log(val);	// <Buffer 03 01 02>
		});
	});
	buf[0] = 0x03;
});