Besides representing all forms of nothing in its interface, FME also allows nothing to be a condition in various tests, let's users set nothing values, and allows bulk updates from one form of nothing to another.
Recognizing Null Values
Various formats have various ways to represent nothing. But, if they support the concept of null, then FME will read any null attributes with a <null> value.
For a workspace to check for incoming nulls, the Tester transformer has specific operators to test for null, empty, and missing values:
Because the Tester interface is incorporated into many facets of FME (such as the TestFilter transformer) you can test for nulls wherever you find that interface.
|New for FME2016 is the "Attribute Has a Value" test. This test returns true when an attribute is not null, is not empty, and is not missing - saving you the inconvenience of having to use those three tests separately.|
Other transformers, such as the Matcher, also allow testing for nulls:
In the case of the Matcher the parameter decides whether null, empty, and missing values should be treated as different values. If set to No, then an attribute that is <null> is treated the same as an attribute that is <missing>. Otherwise, a match only occurs when <null> = <null>