Refactoring several attribute fields at the same time

Question

I have some data from the field survey. In the field, I write down integers that I want to expand afterward. What I do is using the field calculator and something like:

CASE
WHEN A is 1 THEN 'foo'
WHEN A is 2 THEN 'bar' 
ELSE A
END

I have a lot of attribute fields that I have to process and it is a pain doing it this way. Is there a possibility of achieving this in batch?

Answer 1

You can use "Refactor Fields" tool.

• Specify field Type as Text for the fields you need to change.

• Copy the expression to the fields and change the field names in the expression. (I recommend using expression window or a text editor (Notepad) to edit the expression. Because when you edit a character, the cursor goes to the end of the line, unexpectedly)

Answer 2

You can use pyqgis with a dictionary:

Change first four lines:

lyr = QgsProject.instance().mapLayersByName('ok_ak_riks')[0]
sourcefield = 'A'
destfield = 'abcd'
remap = {1:'foo', 2:'bar'}
        
idxdest = lyr.fields().indexFromName(destfield)
idxsource = lyr.fields().indexFromName(sourcefield)
attrmap = {}

for f in lyr.getFeatures():
    if f[sourcefield] in remap:
        attrmap[f.id()] = {idxdest:remap[f[sourcefield]]}
    else:
        attrmap[f.id()] = {idxdest:f[sourcefield]}

lyr.dataProvider().changeAttributeValues(attrmap)