which precondition should I add?

Hi,
if I understand what you want, it should looks like this:

inputPort.addPrecondition(new SimplePrecondition(inputPort, new MetaData(
				ExampleSet.class)));

It doesn't matter how many attributes ExampleSet have.

StaryVena wrote:	StaryVena wrote:
StaryVena wrote:	Hi, if I understand what you want, it should looks like this: inputPort.addPrecondition(new SimplePrecondition(inputPort, new MetaData( ExampleSet.class))); It doesn't matter how many attributes ExampleSet have.

Hi, thanks. But my opeator can only cope with exampleset which has only two attributes.
I want this: if a exampleset with more than two attributes, and it connect to my opeator, there should be a error appeard.

Hi,

there are a couple of ways to achieve this, for example you can use the already mentioned SimplePrecondition class:

inputPort.addPrecondition(new SimplePrecondition(inputPort, new MetaData(ExampleSet.class), true) {

@Override
	/** Override this method to make additional checks. The default implementation does nothing. */
	public void makeAdditionalChecks(MetaData received) {	
		if (((ExampleSetMetaData)received).getAllAttributes().size() != 2) {
			inputPort.addError(new SimpleMetaDataError(Severity.ERROR, inputPort, "I18N.key"));
		}
	}
});

Regards,
Marco