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I would like to join a shapefile to a CSV file in PyQGIS 3.0. So, when I run the following code, it executes without errors but the join action does not succeed. What is wrong with the following code?

layer=iface.activeLayer()
lien_csv="D:/Ghaleb/Projet_SIG/PFE SIG/FICHIERS_SHP/Essai.csv"
infoLyr =QgsVectorLayer(lien_csv,'Table_CSV' , "ogr")
QgsProject.instance().addMapLayers([infoLyr])
infoLyr.isValid()`
info = QgsVectorLayerJoinInfo()
info.setJoinFieldName = "CLE_CSV"
info.setTargetFieldName = "CLE"
info.setJoinLayerId = infoLyr.id()
info.setUsingMemoryCache = True
info.setJoinLayer(infoLyr)
layer.addJoin(info)
lien_save="D:/Ghaleb/Projet_SIG/PFE SIG/FICHIERS_SHP/Vanne_Joint.shp"`
QgsVectorFileWriter.writeAsVectorFormat(layer,lien_save, "iso-8859-15",QgsCoordinateReferenceSystem(32632, QgsCoordinateReferenceSystem.EpsgCrsId), "ESRI Shapefile")
joinedLyr = QgsVectorLayer(lien_save, 'Joined' ,"ogr")
QgsProject.instance().addMapLayers([joinedLyr])
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1
  • does the join work in the GUI?
    – Ian Turton ♦
    May 31, 2018 at 8:06

2 Answers 2

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1

Fairly similar to this post where each function has been slightly renamed (i.e. joinLayerId is now setJoinLayerId in QGIS 3). So you should be setting your joins like the following:

info = QgsVectorLayerJoinInfo()
info.setJoinLayerId = infoLyr.id()
info.setJoinFieldName = "CLE_CSV"
info.setTargetFieldName = "CLE"
info.setUsingMemoryCache = True
info.setJoinLayer(infoLyr)
layer.addJoin(info)
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5
  • Thank you Joseph for your reply. I update the code above. However, the csv fields are added but with NULL attributes. Perhaps, I miss something?
    – ennine
    May 31, 2018 at 11:31
  • @ennine - Perhaps an issue with your data or the joined values do not match in both fields?
    – Joseph
    May 31, 2018 at 12:21
  • I am sorry. I have made a mistake in the CSV name. Now, it works perfectly. The last thing, how can I remove the "custom filed name prefix" in the added fields?
    – ennine
    May 31, 2018 at 12:45
  • @ennine - Not a problem :). I think you can use info.setPrefix('') to make the prefix blank.
    – Joseph
    May 31, 2018 at 12:47
  • @ennine - Most welcome, glad it helped :)
    – Joseph
    May 31, 2018 at 12:53
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The previous answer worked for me, BUT only after I had re-formatted some of the lines. I had to use the following lines to set up the join for it to work correctly.

info.setJoinLayerId(infoLyr.id())
info.setJoinFieldName("CLE_CSV")
info.setTargetFieldName("CLE")
info.setUsingMemoryCache(True)
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