Adding Attributes With SchemaMapper

Liz Sanderson
Liz Sanderson
  • Updated

FME Version

  • FME 2015.x

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 because they are created dynamically based on what fields occur 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 imported 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.

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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 whether or not 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 workbench know you expect to have that field and lets you configure other transformers to work with it.
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For more information about the SchemaMapper transformer see: SchemaMapper Transformer Tutorial.

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