What causes "method name and function required" in siyuan-note/siyuan?

Pass both arguments: bind('methodName', handlerFunction)

method name and function required

Error message

method name and function required

What it means

The siyuan.rpc.bind call requires at least two arguments: the RPC method name (string) and the implementing function. When fewer than two arguments are passed, the call is rejected with this error before any registration occurs. The promise/returned error surfaces to the plugin.

Solutions

Pass both arguments: bind('methodName', handlerFunction)
Ensure the handler is an actual function value, not undefined
Check any spread call provides at least two elements
Verify the API signature in the plugin sample before calling

Example fix

// before
siyuan.rpc.bind('myMethod');
// after
siyuan.rpc.bind('myMethod', (params) => { return {ok: true}; });

Defensive patterns

Strategy: validation

Validate before calling

function assertBindArgs(args) {
  if (!Array.isArray(args) || args.length < 2) {
    throw new TypeError('rpc.bind requires (name, fn) — two arguments');
  }
  if (typeof args[0] !== 'string' || typeof args[1] !== 'function') {
    throw new TypeError('rpc.bind requires a string name and a function');
  }
  return args;
}
// call site: siyuan.rpc.bind(...assertBindArgs([name, handler]))

Type guard

function isBindable(name, fn) {
  return typeof name === 'string' && name.length > 0 && typeof fn === 'function';
}

Try / catch

try {
  siyuan.rpc.bind(name, handler);
} catch (e) {
  if (String(e.message).includes('method name and function required')) {
    console.error('rpc.bind called with missing name or handler:', {name, handler: typeof handler});
  }
  throw e;
}

Prevention

Always define the handler alongside the name in one place
Type-check handler variables (typeof fn === 'function') before binding
Avoid refactors that drop the handler argument from bind calls

When it happens

Trigger: Calling rpc.bind('myMethod') without the function, or bind() with no arguments; spreading an argument array shorter than two.

Common situations: Forgetting the handler after refactoring; passing the implementation via an object config form the API does not support; undefined variable silently dropped from the call.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of siyuan-note/siyuan@9f775e8a12 (2026-09-19). Data as JSON: /api/errors/e8f2fb720edf36c2. Report an issue: GitHub.

Appendix: source

Thrown at kernel/plugin/api_rpc.go:46

// injectRpc adds siyuan.rpc method for RPC method registration.
func injectRpc(p *KernelPlugin, rt *goja.Runtime, siyuan *goja.Object) (err error) {
	defer func() {
		if r := recover(); r != nil {
			err = fmt.Errorf("injectRpc: %v", r)
		}
	}()

	rpc := rt.NewObject()

	lo.Must0(rpc.Set("bind", rt.ToValue(func(call goja.FunctionCall, rt *goja.Runtime) goja.Value {
		promise, resolve, reject := rt.NewPromise()

		var argErr error
		var name string
		var method goja.Callable
		var descriptions []string
		if len(call.Arguments) < 2 {
			argErr = fmt.Errorf("method name and function required")
		} else {
			nameArg := call.Argument(0)
			methodArg := call.Argument(1)
			descArgs := call.Arguments[2:]
			if goja.IsString(nameArg) {
				name = nameArg.String()
			} else {
				argErr = fmt.Errorf("first argument must be method name string")
			}
			if argErr == nil {
				if methodJs, ok := goja.AssertFunction(methodArg); ok {
					method = methodJs
				} else {
					argErr = fmt.Errorf("second argument must be a function")
				}
			}
			if argErr == nil {
				descriptions = make([]string, len(descArgs))

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