karatelabs/karate · error · RuntimeException

body() needs at least one argument

Error message

body() needs at least one argument

What it means

Arity guard in HttpRequestBuilder's body() JS binding: setting the request body requires at least one argument (the body value, converted downstream). Fires when builder body() is chained with no arguments.

Solutions

1. Pass a value explicitly: `body({ a: 1 })`, `body('text')`, `body(xmlNode)`.
2. Check the variable is defined before the call: `if (payload != null) body(payload)`.
3. If you truly want no body, simply omit the body() call.
4. For structured payloads use request/body keywords or pass a string/Map/List which the builder converts.
5. ­

Example fix

// before
var payload = /* may be undefined */;
body(payload)
// after
if (payload != null) body(payload)

if (payload != null) builder.body(payload);

function hasBody(v) { return v !== undefined && v !== null; }

try { builder.body(p); } catch (e) { if (('' + e).includes('at least one argument')) logger.warn('skipping body, payload undefined'); else throw e; }

When it happens

Trigger: Calling `body()` with zero arguments, e.g. a JS variable holding the payload is undefined: `body(payload)` where payload is undefined collapses to no argument in the JS-to-Java bridge.

Common situations: Payload built by a preceding step that failed or returned null/undefined; forgetting to pass the request body in a generated request script.

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

• params() needs a map argument
• headers() needs a map argument
• read() needs at least one argument
• sysenv() needs the environment-variable name
• sysprop() needs the property name

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/c54333097c543ec3. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/http/HttpRequestBuilder.java:788

            return this;
        };
    }

    private JavaInvokable path() {
        return args -> {
            for (Object arg : args) {
                if (arg != null) {
                    path(arg + "");
                }
            }
            return this;
        };
    }

    private JavaInvokable body() {
        return args -> {
            if (args.length == 0) {
                throw new RuntimeException("body() needs at least one argument");
            }
            body(args[0]);
            return this;
        };
    }

    @Override
    public Object jsGet(String key) {
        switch (key) {
            case "get":
            case "post":
            case "put":
            case "delete":
            case "head":
            case "options":
            case "trace":
            case "connect":
            case "patch":

View on GitHub (pinned to a22eb90246)