usememos/memos · error

startsWith expects exactly one argument

Error message

startsWith expects exactly one argument

What it means

buildStartsWithPredicate translates t.startsWith("prefix"). It validates that the call target is the iteration variable and that exactly one argument is passed. More or fewer than one argument is rejected.

Source

Thrown at internal/filter/parser.go:960

	}

	return &EqualsPredicate{Value: valueStr}, nil
}

func isIterVarExpr(expr *exprv1.Expr, iterVar string) bool {
	target := expr.GetIdentExpr()
	return target != nil && target.GetName() == iterVar
}

// buildStartsWithPredicate extracts the pattern from t.startsWith("prefix").
func buildStartsWithPredicate(call *exprv1.Expr_Call, iterVar string) (PredicateExpr, error) {
	// Verify the target is the iteration variable
	if target := call.Target.GetIdentExpr(); target == nil || target.GetName() != iterVar {
		return nil, errors.Errorf("startsWith target must be the iteration variable %q", iterVar)
	}

	if len(call.Args) != 1 {
		return nil, errors.New("startsWith expects exactly one argument")
	}

	prefix, err := getConstValue(call.Args[0])
	if err != nil {
		return nil, errors.Wrap(err, "startsWith argument must be a constant string")
	}

	prefixStr, ok := prefix.(string)
	if !ok {
		return nil, errors.New("startsWith argument must be a string")
	}

	return &StartsWithPredicate{Prefix: prefixStr}, nil
}

// buildEndsWithPredicate extracts the pattern from t.endsWith("suffix").
func buildEndsWithPredicate(call *exprv1.Expr_Call, iterVar string) (PredicateExpr, error) {
	if target := call.Target.GetIdentExpr(); target == nil || target.GetName() != iterVar {

View on GitHub (pinned to 14d757ce1f)

Solutions

1. Use the textual form tag.exists(t, t.startsWith("work"))
2. Emit exactly one constant string argument when building the call AST

if err := r.Render(cond); err != nil {
    if strings.Contains(err.Error(), "startsWith expects exactly one argument") {
        return errors.New("call startsWith with a single quoted prefix")
    }
    return err
}

When it happens

Trigger: Programmatically constructed startsWith call with wrong arity; textual CEL always emits one arg, so this is a guard against malformed ASTs.

Common situations: AST-building tests or custom CEL environments emitting startsWith with 0 or 2 args.

Related errors

• endsWith expects exactly one argument
• contains expects exactly one argument
• comprehension accumulator must be initialized with a constan
• unsupported comprehension type (supported: exists, all, exis
• comprehension loop step must be a call expression

AI-assisted analysis of usememos/memos@14d757ce1f (2026-08-15). Data as JSON: /api/errors/26dbd23de5bc1cc4. Report an issue: GitHub.