According to several solved questions in this forum, there are two recommended ways to automatically remove attributes that only conatain NULL or empty values: using a small python script or using the NullAttributeMapper. Unfortunately both suggestions do not work for me (FME Desktop/Form 2022.2). Both the PythonCaller and the NullAttributeMapper keep the Null-Attributes and they are present when I write to Excel (see attached workspace). Is there something wrong in my workflow or is there an updated solution? Thanks for any suggestions!
Solved
Automatically remove unused attributes
+8- Contributor
Best answer by pflegpet
Hi @hkingsbury , thank you! Your modified Python code now removes all unused attributes. I also found out, that you could also use the SchemaScanner to achieve the same result (also using a dynamic writer). You just have to set it to "Ignore empty attributes" and exclude the schema attributes starting with fme_ (which is basically what you did in your script). I attached both solutions in case anyone needs this as a reference in the future.
+51- Celebrity
As you're looking to dynamically change the schema (ie the schema is dependent/defined by the data) your going to need to follow a dynamic workflow where you make use of schema attributes and dynamic writers
https://community.safe.com/s/article/dynamic-workflow-tutorial-introduction
To achieve what your looking for, i've made a minor addition to the Python in the SchemaSetter custom transformer - https://hub.safe.com/publishers/safe-lab/transformers/schemasetter
In the uploaded workbench, you can see the changes i've made on lines 84-86. All my change does is that if the attribute does not have a value, it will exclude it from the schema creation. It then flows into a dynamic writer that uses the schema list on the attribute to define the excel sheets output fields
+8- Contributor
- Best Answer
Hi @hkingsbury , thank you! Your modified Python code now removes all unused attributes. I also found out, that you could also use the SchemaScanner to achieve the same result (also using a dynamic writer). You just have to set it to "Ignore empty attributes" and exclude the schema attributes starting with fme_ (which is basically what you did in your script). I attached both solutions in case anyone needs this as a reference in the future.
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+51- Celebrity
pflegpet wrote:
Hi @hkingsbury , thank you! Your modified Python code now removes all unused attributes. I also found out, that you could also use the SchemaScanner to achieve the same result (also using a dynamic writer). You just have to set it to "Ignore empty attributes" and exclude the schema attributes starting with fme_ (which is basically what you did in your script). I attached both solutions in case anyone needs this as a reference in the future.
Good to know re the SchemaScanner, I don't deal with dynamic processes all that much and haven't had the chance to use that yet, but will investigate it further :)
+49- Celebrity
+51- Celebrity
redgeographics wrote:
Hmmm, I don’t sorry. But looking at the custom transformer, around those lines:
I imagine I was checking the value of att and only passing it through if it wasn’t none/null/empty
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