quarkusio/quarkus · error

Index parameter is missing

Error message

Index parameter is missing

What it means

Qute's ArrayResolver resolves array access in templates via methods like `get(index)`. It throws this IllegalArgumentException when a `get` call is made on an array base value without supplying the required index parameter. The resolver requires exactly one parameter that evaluates to an Integer.

Solutions

1. Supply the index parameter in the template: use `{myArray.get(0)}` or `{myArray.get(i)}`.
2. Use bracket/property index syntax instead: `{myArray.0}` or `{myArray[i]}` for loops over indices.
3. Guard with `{#if myArray.size > 0}` before calling get to ensure valid access.

Example fix

// before (template)
{myArray.get}
// after (template)
{myArray.get(0)}

// Java check before rendering
if (array == null) throw new IllegalArgumentException("array data missing");
// in template, prefer guarded form:
// {#if index >= 0 && index < array.length}{array.get(index)}{/if}

When it happens

Trigger: A template expression on an array base value uses `get` with no parameter, e.g. `{myArray.get}` instead of `{myArray.get(0)}`, and `context.getParams().isEmpty()` is true in ArrayResolver.resolve at ValueResolvers.java:444.

Common situations: Template typos where parentheses/index were dropped; generating templates dynamically and forgetting to interpolate the index; refactoring `{myArray.0}` into `{myArray.get}` without adding the index argument.

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

• Literal must not be null
• Cannot coerce to a BigDecimal
• Engine not set
• Expresion command is reserved: " + command
• Expresion command must be an ASCII char: " + command

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/789fab9273e7cd4c. Report an issue: GitHub.

Appendix: source

Thrown at independent-projects/qute/core/src/main/java/io/quarkus/qute/ValueResolvers.java:444

                }
                Expression indexExpr = context.getParams().get(0);
                if (indexExpr.isLiteral()) {
                    Object literalValue = indexExpr.getLiteral();
                    if (literalValue instanceof Integer) {
                        return CompletedStage.of(takeLastArray((Integer) literalValue, context.getBase()));
                    }
                    return Results.notFound(context);
                } else {
                    return context.evaluate(indexExpr).thenCompose(n -> {
                        if (n instanceof Integer) {
                            return CompletedStage.of(takeLastArray((Integer) n, context.getBase()));
                        }
                        return Results.notFound(context);
                    });
                }
            } else if (name.equals(GET)) {
                if (context.getParams().isEmpty()) {
                    throw new IllegalArgumentException("Index parameter is missing");
                }
                Expression indexExpr = context.getParams().get(0);
                if (indexExpr.isLiteral()) {
                    Object literalValue = indexExpr.getLiteral();
                    if (literalValue instanceof Integer) {
                        return CompletedStage.of(Array.get(context.getBase(), (Integer) literalValue));
                    }
                    return Results.notFound(context);
                } else {
                    return context.evaluate(indexExpr).thenCompose(idx -> {
                        if (idx instanceof Integer) {
                            return CompletedStage.of(Array.get(context.getBase(), (Integer) idx));
                        }
                        return Results.notFound(context);
                    });
                }
            } else {
                // Try to use the name as an index

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