JS serialize binary error "Unknown base64 encoding at char: @"

[dnovak270]

Create simple proto file:

syntax = "proto3";

message Test {
  bytes test_bytes_field = 1;
}

Generate code using buf:

# buf.gen.yaml
version: v1
plugins:
  - name: grpc-web
    out: ./src/grpc
    opt: import_style=commonjs+dts,mode=grpcwebtext
  - name: js
    out: ./src/grpc
    opt: import_style=commonjs,binary

Try setting a non base64 char (e.g. @) to test_bytes_field and use serializeBinary method on generated jspb.Message:

try {
  const test = new Test();
  test.setTestBytesField('@');
  test.serializeBinary();
} catch (e) {
  console.error({ e });
}

Results in an error "Unknown base64 encoding at char: @"

[dibenede]

This is working as intended: a string argument is intended to be used for base64 strings. Unfortunately, there's nothing in the setter API to signal as much, so the error only pops up during serialization:

protobuf-javascript/binary/utils.js

Lines 1093 to 1120 in 566f359

	jspb.utils.byteSourceToUint8Array = function(data) {
	if (data.constructor === Uint8Array) {
	return /** @type {!Uint8Array} */ (data);
	}
	if (data.constructor === ArrayBuffer) {
	data = /** @type {!ArrayBuffer} */ (data);
	return /** @type {!Uint8Array} */ (new Uint8Array(data));
	}
	if (data.constructor === Array) {
	data = /** @type {!Array<number>} */ (data);
	return /** @type {!Uint8Array} */ (new Uint8Array(data));
	}
	if (data.constructor === String) {
	data = /** @type {string} */ (data);
	return goog.crypt.base64.decodeStringToUint8Array(data);
	}
	if (data instanceof Uint8Array) {
	// Support types like nodejs Buffer and other subclasses of Uint8Array.
	data = /** @type {!Uint8Array} */ (data);
	// Make a shallow copy to ensure we only ever deal with Uint8Array
	// exactly to ensure monomorphism.
	return /** @type {!Uint8Array} */ (
	new Uint8Array(data.buffer, data.byteOffset, data.byteLength));
	}

Depending on your use case, you may just want to use a Uint8Array instead.