com.im.df.api.dml
Class Operators.NullOperator

java.lang.Object
  com.im.df.api.dml.DFOperator
      com.im.df.api.dml.Operators.SimpleFieldValuesOperator
          com.im.df.api.dml.Operators.NullOperator

Enclosing class:

Operators

public static class Operators.NullOperator
extends Operators.SimpleFieldValuesOperator

IS NULL/ IS NOT NULL operators

Constructor Summary

Operators.NullOperator(String displayName)

Method Summary

boolean

isFieldAcceptableAsOperand(DFField field) This is just an utility method which must be implemented by subclasses.

Methods inherited from class com.im.df.api.dml.Operators.SimpleFieldValuesOperator

getReturnType, getValidFormatMsg, isEmptyStringAllowed, parseOperands, validate

Methods inherited from class com.im.df.api.dml.DFOperator

correctNumberOfOperands, getDisplayName, getDisplayNameInExpression, getMaxOperands, getMinOperands, getToStringPart, toString, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Operators.NullOperator

public Operators.NullOperator(String displayName)

Method Detail

isFieldAcceptableAsOperand

public boolean isFieldAcceptableAsOperand(DFField field)

Description copied from class: DFOperator

This is just an utility method which must be implemented by subclasses. It test if the given field is acceptable as operand for this DFOperator. It can return true even for fields which are recognized as invalid later. This is just rough test in the beginning of validation to filter inappropriate fields.

For example some operator takes two operands of different types (text, integer,...), but both must be of the same type. In this case this method returns true for all text, integer etc. fields, but if you use combination of [text, integer] as operands, it will be invalid.

Overrides:

isFieldAcceptableAsOperand in class Operators.SimpleFieldValuesOperator

Parameters:

field - The field to be tested

Returns:

True if field seems to be acceptable, false otherwise.