Using QGIS Processing Modeler to split polygons with lines

Question

I am trying to use the QGIS Processing Modeler to split polygons with lines. Here is the workflow I have so far. It is sucessful.

enter image description here

I then add "Grid" and "Split With Lines" to split the polygons. No matter what combination of options I select it always fails. The end result I get for the split polygons is grid of lines. I have also tried to change the "Parent Algorithms" option to a number of combinations with no luck.

Here is the end product I would like to achieve. enter image description here

Here is what I think should succeed, but does not. enter image description here

Multiple selection is from the parent algorithm selection.

enter image description here

Here is the result. enter image description here

• Erik: Did you just delete your old question and posted it as new instead of editing the old one?
• wfgeo: Can you post an image of the parameters you have input for "Split Grid with Lines"?

Answer 1

Your input for Split with lines is the grid and it tries to cut that grid with your polygons. It's the other way around:

• Input layer is the layer you want to cut
• Split layer is the layer with which to split

Check the tool documentation by clicking on the Help button on bottom right of the tool windows.

If you want to get past the grid output not being available in the split tool (in the graphical modeler), use this:

After the grid tool, add an Extract by expression with the expression $id IS NOT NULL. The output of that tool will be available in the split tool.

• Dan Olson: The Grid does not appear in the Split Layer Input for some reason.
• Dan Olson: Nice work. You solved the problem I had been working on for a couple of days. Thanks.