Feature request #21337

Graphical Builder - Link between Expression Paramenter and Table/Vector Field

Added by Hans-Peter Klossek over 1 year ago. Updated over 1 year ago.

Status:Open
Priority:Normal
Assignee:-
Category:Processing/Modeller
Pull Request or Patch supplied:No Resolution:
Easy fix?:No Copied to github as #:29155

Description

Hello folks,

I have a feature request:

It would be nice to implement a link between the input parameter 'expression' and 'table/vector field' so it is useable for a dynamic workflow with a parameter like '@field_namen' inside of a expression. I have tried this in the field calculator, it is working only for the column name but the field values go in the 'null-nirvana'.

Thanks and best regards, Hape

example.jpg (94.1 KB) Hans-Peter Klossek, 2019-02-21 05:10 PM

History

#1 Updated by Alexis Roy-L over 1 year ago

Hans-Peter Klossek wrote:

Hello folks,

I have a feature request:

It would be nice to implement a link between the input parameter 'expression' and 'table/vector field' so it is useable for a dynamic workflow with a parameter like '@field_namen' inside of a expression. I have tried this in the field calculator, it is working only for the column name but the field values go in the 'null-nirvana'.

Thanks and best regards, Hape

Just out of curiosity, what is the intended use case of this?

One thing that is doable is to use the select by attribute and split the workflow in two.

Since this would be done on the feature scale I'm not too sure what the gain would be.

#2 Updated by Nyall Dawson over 1 year ago

You can use the existing "attribute" function, eg

attribute($currentfeature, @fieldparametername)

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