Creating the TO_CHAR function for conversion of dates in TOPLINK.

		ExpressionOperator toChar = new ExpressionOperator();
		toChar.addSelector("toChar");
		Vector s = new Vector();
		s.addElement("TO_CHAR(");
		s.addElement(", 'YYYYMMDD')");
		toChar.printsAs(s);
		toChar.bePrefix(); 
		toChar.setNodeClass(TOPLink.Private.Expressions.FunctionExpression.class);
		ExpressionOperator.initializeOperators();
		ExpressionOperator.addOperator(toChar);


Using the new expression


					Expression expr = ExpressionOperator.getOperator("toChar").expressionFor(exp.get("fieldVaststellingsdatum"));
					datumExp = expr.equal( format(beginCal, "yyyyMMdd"));