Renaming or deleting fields in multiple layers without creating new layers (QGIS)

Question

I am very new to QGIS.

I have added three new fields using batch processor to all my layers (150 or so), but named them incorrectly. All I want to do is rename them correctly but I can't seem to do this. Everything involves creating new layers with the renamed column (refractor fields) or if I deleted the columns and add them again then again it creates new layers without them and keeps the old ones. It will take forever to save all these files under a new name and a new place, so I was wondering if there is any way to delete or rename the columns in the same layers and not create new ones.

Answer 1

I think a script would be beneficial for this amount of layers. If you load all your layers into QGIS, you can copy/paste the following code into the Python Console (load the console using Ctrl + Alt + P). Replace the names in the dictionary with your own:

# Dictionary to hold old names as keys; new names as values
dict_of_field_names = { 'A': 'new_A',
                        'B': 'new_B',
                        'C': 'new_C'
                        }

# Iterate through each layer
for layer in QgsProject.instance().mapLayers().values():
    # Store all field names in a list
    fields = [field.name() for field in layer.fields()]
    # Iterate through each field
    for field in layer.fields():
        # Check if old field name matches those in the dictionary
        if field.name() in dict_of_field_names:
            # If yes then edit the layer
            with edit(layer):
                # Get index of field containing the old field name
                idx = layer.fields().indexFromName(field.name())
                #  Change old field name to its corresponding new field name
                layer.renameAttribute(idx, dict_of_field_names[field.name()])