Forcing input parameters in QGIS processing scripts?

Question

Is there any way to force input parameters (e.g. data provider, geometry type, field type) in processing scripts?

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• whyzar: What have you attempted thus far?
• Steven Kay: are you familiar with the Graphical Modeller? Or do you need fields to be made mandatory/required outside of the modeller, e.g. running a single algorithm from a Python script?

Answer 1

For processing scripts, I don't think it is currently possible to filter out a layer's data provider specifically for PostGIS layers. Looking at the parameters.py file for the processing framework, it seems that you can only specify the following for all loaded shapefiles:

• Geometry type: (point, line or polygon)
• Field type: (number, string)

So currently, you could use something like:

##Input table=vector point
##Distance field=field number Input table

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You could try and edit the file to include a PostGIS parameter (not sure how much editing is required) which you can find in your QGIS directory. E.g.:

C:/Program Files/QGIS 2.18.2/apps/qgis/python/plugins/processing/core/parameters.py