5

Using the QGIS expression string builder, there is a preview window at the bottom that shows the pre-calculated output for the current feature selected. However, with more complex expressions, calculation can become complex and takes a while. The expression string builder can become slow or even hang. This is especially true for aggregate or (nested) array_foreach functions.

Editing an expression in such circumstances is difficult as each character entered or deleted starts calculation from the start and each time it takes a while until it becomes responsive again.

Is there a way to disable/deactivate the preview in QGIS expression string builder?

Improve this question
0

2 Answers 2

Reset to default
7

A simple workaround is to make the expression invalid, e.g. by removing the closing bracket. Add the bracket back when you are done with your changes to test the expression.

Improve this answer
1
  • But if you make the function invalid, you can't tell if you make syntax errors.
    – pigreco
    Commented Dec 19, 2021 at 16:28
4

When I have to study or create complex expressions I put a filter on the layer:

enter image description here

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.