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There are many questions like this but either they propose to implement a new method to update values or describe how to set default values for fields in GUI.

I'm writing a QgsProcessingAlgorithm and need to set default values when modifying fields using the QgsEditorWidgetSetup either for 'KeyValue' if the fieldtype is hstore or 'TextEdit' if it's some kind of String-field. Here's what I've tried (for 'TextEdit' because it's simpler):

sourceLayer.setEditorWidgetSetup(index, QgsEditorWidgetSetup('TextEdit', 
{
   'DefaultValue': 'DefValue',
   'Defaults': 'DefValue',
   'Default': 'DefValue',
   'IsMultiline': 'True',
   'UseHtml': 'False'
}

The properties 'IsMultiline' and 'UseHtml' work flawlessly but none of the defaults is accepted.

A often proposed approach is to use the Python console to get the QgsEditorWidgetSetup config of a field configured via GUI. This is done by the following code:

layer = qgis.utils.iface.activeLayer()
layer.fields().names()
idx = layer.fields().indexFromName('text')
field = layer.fields()[idx]
field.editorWidgetSetup().config()

Unfortunately the output is just: {'IsMultiline': False, 'UseHtml': False} Although of course the default value I configured is working fine when I add new features through the attribute table.

Any ideas?

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1 Answer 1

Reset to default
3

You can set a layer's field default value with this following code, by using the QgsVectorLayer's setDefaultValueDefinition method :

layer = qgis.utils.iface.activeLayer()
my_field = layer.fields().names()[1]  # second field
idx = layer.fields().indexFromName(my_field)
default_value = QgsDefaultValue()
default_value.setExpression("'This is the DefaultValue'")
layer.setDefaultValueDefinition(idx, default_value)
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6
  • Thanks so much J :-) However, from the PyQGIS API perspective this isn't very straightforward. Furthermore, there isn't a getDefaultValueDefinition, is there?
    – Sickboy
    Commented Jun 27, 2022 at 6:47
  • You have field.defaultValueDefinition() or layer.defaultValueDefinition(idx).
    – J. Monticolo
    Commented Jun 27, 2022 at 7:38
  • Thanks :-) However, a set-method but no get-method isn't very straightforward again.
    – Sickboy
    Commented Jun 28, 2022 at 4:43
  • @Sickboy: that is how Qt is designed in general, take a look here setter setCurrentIndex, getter currentIndex : doc.qt.io/qt-6/qcombobox.html#currentIndex-prop.
    – J. Monticolo
    Commented Jun 28, 2022 at 6:58
  • @Sickboy: if my answer is valid and answers your question, don't forget to accept it.
    – J. Monticolo
    Commented Jun 30, 2022 at 9:05

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