I am trying to set the edit type of a vector layer to use a value relation, by pyqgis. So my question is exactly the same as this, except now it is qgis 2.14. I found that setEditForm is deprecated and this method is recommended instead:


setWidgetType sets the edit widget correctly but then I have the same problems as in the question regarding qgis 2.0. I.e. python commands are processed without errors or warnings but the when I check the properties in QGIS, the widget settings are empty:

vlayer.valueRelation(index).mLayer = target_layer.id()
vlayer.valueRelation(index).mKey = key_field
vlayer.valueRelation(index).mValue = value_field
vlayer.valueRelation(index).mAllowNull = True
vlayer.valueRelation(index).mOrderByValue = True

How do I define the value relation by pyqgis in qgis 2.14?

1 Answer 1


The options for the widget configurations are passed in as dict.

It's best to inspect first what a manually configured (and working) configuration looks like.


With this command you will see, that a ValueRelation accepts the following configuration options:

  • FilterExpression
  • Layer
  • UseCompleter
  • AllowMulti
  • AllowNull
  • OrderByValue
  • Value
  • Key

Now simply do it the other way round:

cfg = dict()
cfg['Layer'] = target_layer.id()
cfg['Key'] = key_field
cfg['Value'] = value_field
cfg['AllowNull'] = True
cfg['OrderByValue'] = True
# Add more if you like
vlayer.editFormConfig().setWidgetConfig(index, cfg)
  • This is a very clear and useful answer that solved my problem. Thank you Matthias!
    – joskal
    Aug 12, 2016 at 18:56
  • can you provide the link of the documentation like what does UseCompleter do ? and how to use it ? May 26, 2017 at 13:30

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