Question
After adding SchemaMapper to my workspace, why don't I see any of the new attributes it is supposed to add?
Answer
SchemaMapper doesn't auto-expose attributes created dynamically, as they are based on the fields present in the source dataset. For example, if you have a schema mapping table that maps:
a > x b > y c > z
Then you have 2 source features with the following attributes:
F1: a F2 a,b
The result features are with the new mapped attribute names:
F1: x F2: x,y
To get access to attributes within the workspace, you can add an AttributeExposer after the SchemaMapper.
AttributeExposer has an import function to allow you to input the destination field names from your schema mapping table. Edit the AttributeExposer parameters and choose import attribute values. If you are using Feature Caching, you can import attribute names from the cached data - use Import From Feature Cache. If you have a column of field names to import from a file (such as from a schema mapping table), use Import From Dataset.
Note that while Workbench doesn't show dynamic attributes internally in your workspace, FME can still use them. If you have a field in your destination feature type and SchemaMapper has populated that field, it will be written out, regardless of whether it is actually exposed in the Workbench schema. Conversely, exposing an attribute will not automatically fill it with data if you don't configure your SchemaMapper correctly. Exposing just lets the workbench know that you expect to have that field, and allows you to configure other transformers to work with it.
For more information about the SchemaMapper transformer, see: SchemaMapper Transformer Tutorial.