Question

Looping in FME with Sorter

7 years ago
12 July 2016
4 replies
8 views

je6thoma
11 replies

To whom this may concern:

With the current workbench I'm trying to execute, I'm trying to sort through the attributes before following through with a loop (e.g. ). With looping (as shown in the screenshot), however, I receive an error message which reads as follows:

"ERROR |Transformer/Factory PolynomialFunction_Sorter_2 is blocking and cannot be used in a loop, but was found between 'Loop to PolynomialFunction_Polynomial_Function_Loop1468337910 Input Splitter' and 'PolynomialFunction_Polynomial_Function_Loop1468337910 Input Splitter'".

May I ask if there are any ways with which I could sort the values (working with an Excel worksheet as the reader and am looking to write to another Excel worksheet) in a loop without receiving the error message?

Best Regards,

JE6THOMA

4 replies

G

+3

as the p-sorter is a blocking function, maybe try export the custom bit as transformer first?. Prior to actually adding the loop.

M

+5

The problem is that a loop processes one feature at a time - so feature 1 runs through the loop until the condition is met, then feature 2, then feature 3, etc. However, you have a Sorter transformer, which relies on being able to access features 1, 2, 3, etc all simultaneously.

So FME is telling you that a "blocking" transformer - that requires all the features - is invalid in a loop that processes one at a time.

I think it would be helpful to know what you are trying to do - as someone might have a way to process the data without a loop, or find a way to avoid sorting data inside the loop.

As @gio says, it is possible to run a loop with a blocking transformer like this. However, you have to export the custom transformer (File > Export as Custom Transformer) to allow this to happen. It's a fairly advanced technique - I avoid it whenever I can - so I think it would be better to first look at if we can resolve the scenario without having to do that.