A high proportion of the top 25 transformers are support transformers for managing attributes. These create new attributes, rename them, set values, and delete them.
A key use for these transformers is to rename attributes for the purpose of schema mapping.
The key attribute-management tasks and the transformers that can be used are as follows:
| Task | Transformers |
|---|---|
| Create Attributes | AttributeCreator, AttributeManager |
| Set Attribute Values | AttributeCopier, AttributeCreator, AttributeManager, AttributeRenamer |
| Remove Attributes | AttributeKeeper, AttributeManager, AttributeRemover, BulkAttributeRemover |
| Rename Attributes | AttributeManager, AttributeRenamer, BulkAttributeRenamer |
| Copy Attributes | AttributeCopier, AttributeCreator, AttributeManager |
| Sort Attributes | AttributeManager |
| Change Attribute Case | BulkAttributeRenamer |
| Add Prefixes/Suffixes | BulkAttributeRenamer |
Many of these transformers can carry out similar operations, and you can see that the AttributeManager does so many tasks you can use it almost exclusively.
| WARNING |
| Don't misunderstand the BulkAttributeRenamer. It changes the case - or adds suffixes/prefixes - to the attribute name, not the attribute value. |
A List in FME is a mechanism that allows multiple values per attribute.
For example, the attribute myAttribute can only contain a single value.
However, the list attribute myList{}.myAttribute can contain multiple values as:
myList{0}.myAttribute
myList{1}.myAttribute
myList{2}.myAttribute
etc.
There are various transformers designed to operate specifically on lists - they can be found in the Lists category of the transformer gallery - and list functionality is built into other transformers (such as the AttributeCreator) too.
For further reading check out this article on Attribute Management on the Safe Software blog.