[Qgis-user] pyQGIS - set attributes by expression

[Wouter Impens]

Hi,

Hope anyone can help me with this:

I'm trying to iterate over the fields of a vector layer (using the index)
and fill in the values by an expression

 my_features = a_layer.getFeatures()
    for a_feat in my_features:
        mijn_index = a_feat.fieldNameIndex('perc_nr')
        value = an_expr
         a_feat.setAttribute(mijn_index, value)

    a_layer.commitChanges()

I don't get an error but nothing is filled in. I evaluated the expression
and it's true. It also works in the field calculator.

Anyone an idea?


Kind regards
Wouter
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