karatelabs/karate · error · JsErrorException

cannot get . (on )

Error message

cannot get . (on )

What it means

Thrown by JavaUtils.getOrNotFound when a member (field or getter method) was found by name on the Java object but the reflective read itself fails — IllegalAccessException, InvocationTargetException, etc. Reported as 'cannot get .<name> (on <TypeName>)'.

Solutions

1. Call the underlying getter method explicitly to see the real wrapped exception.
2. Ensure the object is fully initialized before reading its properties.
3. Use the public interface of the object rather than reflective access to non-public members.
4. Add --add-opens JVM flags if JPMS blocks an unavoidable internal access.

Example fix

// before
var val = config.connection; // getter throws inside
// after
var val = config.getConnection(); // surfaces real cause directly

try { obj.getClass().getMethod('getProp').invoke(obj); } catch (e) { karate.log('getter fails:', e); }

try { return obj.prop; } catch (e) { if (String(e).indexOf('cannot get') !== -1) { return safeDefault; } throw e; }

When it happens

Trigger: Reading obj.someName where the field/getter exists but is not accessible, or the getter throws when invoked (lazy init failure, state-dependent getters).

Common situations: Getters that throw due to uninitialized state or missing environment; JPMS-encapsulated classes; reading fields on package-private implementation classes.

Related errors

• is not a constructor
• . is not a function (called on )
• no instance property:
• toBean() needs two arguments: object and class name
• object is null

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/f13af81c2a92f76a. Report an issue: GitHub.

Appendix: source

Thrown at karate-js/src/main/java/io/karatelabs/js/JavaUtils.java:257

     * an error — the JS bridge, which turns it into {@code undefined}. Building a TypeError for
     * that, stack trace and all, was pure cost on a path that discards it. A getter that throws
     * still raises, because that is a real failure.
     */
    static Object getOrNotFound(Object object, String name) {
        Object member = resolveMember(object.getClass(), name);
        if (member == NOT_FOUND) {
            return NOT_FOUND;
        }
        if (member == METHOD_MARKER) {
            return new JavaObject(object).getMethod(name);
        }
        try {
            if (member instanceof Field field) {
                return field.get(object);
            }
            return ((Method) member).invoke(object, EMPTY);
        } catch (Exception e) {
            throw JsErrorException.typeError("cannot get ." + name + " (on " + jsTypeName(object.getClass()) + ")");
        }
    }

    static void set(Object object, String name, Object value) {
        String setterName = "set" + name.substring(0, 1).toUpperCase() + name.substring(1);
        Object[] args = new Object[]{value};
        try {
            Method method = findMethod(object.getClass(), setterName, args);
            if (method == null) {
                throw new RuntimeException("no such method: " + setterName);
            }
            method.invoke(object, args);
        } catch (Exception e) {
            throw JsErrorException.typeError("cannot set ." + name + " (on " + jsTypeName(object.getClass()) + ")");
        }
    }

    //==================================================================================================================

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