Hi,
I need to filter some ArcGIS Online Portal Readers based on a unique ID that exists also in another reader (file geodatabase).
Example
Reader 1: ArcGIS Portal features w/ UID
Reader 2: File Geodatabase features w/ UID
Reader 1 should only load features that have a UID that match Reader 2.
The UID fields are the same format. Is this possible? Please let me know if can provide further details. I am a beginner/intermediate FME user focused on GIS.
Thank you!
A quick suggestion for you to try.
Create a Reader for File Geodatabase in FME Workbench and for the ArcGIS Portal Features use the FeatureReader transformer with its INITIATOR port connected to the File Geodatabase feature types.
I think in the FeatureReader, you can set the WHERE clause based on the UID of the Geodatabase features.
I do not have an Esri license to try this out and would be curious to know if this worked for you.
Happy FME 
ing
Cheers
SRG