How do I get a list of fields that have been joined to a layer, or how can I check if a specific field has been joined?

In older versions there seemed to be field.source(), but this is not available anymore.

I am not performing the join via PyQGIS. The join is done manually and I would just like to use PyQGIS to detect which fields have been joined.

1 Answer 1


One can detect which fields have been joined by means of the QgsFields class and its method fieldOrigin:

Returns the field's origin (value from an enumeration).

from qgis.core import QgsProject

layer = QgsProject.instance().mapLayersByName("points")[0]

joined_fields = []

if len(layer.vectorJoins()) > 0:
    fields = layer.fields()
    for field in fields:
        field_name = field.name()
        indx = fields.indexOf(field_name)
        if fields.fieldOrigin(indx) == fields.OriginJoin:
        # or if fields.fieldOrigin(indx) == 2:

The above code will result in a list of fields that have been joined to a layer. In my case it will be:

['month', 'month2', 'month3']

2 = OriginJoin means that this field comes from a joined layer.

OriginJoin Field comes from a joined layer (originIndex / 1000 = index of the join, originIndex % 1000 = index within the join)


  • 1
    Works very well. Thank you for providing a very clear answer! Nov 1, 2023 at 15:04

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.