Add file name as attribute field in QGIS

Question

I have a folder with several shapefiles (around 75). I would like to create a new field into each .shp file which has to be filename. i.e: 20201003.shp --> 20200103.shp (New field 'Fecha' = 20200103)

I have tried this but nothing is done and no errors neither:

import os, datetime
`shapefolder = r'C:\Users\juavafer\Proyectos\Costas_CoastSat\Output\CMillor\Comparacion\matlab\Qgis'
newfieldname = 'test3'
for root, folder, files in os.walk(shapefolder):
 #Find the shapefile
 for file in files:
 fullpath = os.path.join(root,file)
 if os.path.isfile(fullpath) and fullpath.endswith('.shp'):
 print(fullpath)
 #Extract numbers from filename
 datename = ''.join([num for num in file if num.isdigit()])
 #Create a datetime object and convert to string in format 'YYYY-MM-DD', which is what a shapefile wants
 QgsField(name='test3', type=QVariant.String, len=20)
 newdatename = dt.strftime('%Y%m%d')
 
 print(datename)
 # dt = datetime.datetime.strptime(datename, '%Y%m%d')
 # newdatename = dt.strftime('%Y%m%d')
 print(datename)
 #Add the field https://opensourceoptions.com/blog/pyqgis-adding-and-deleting-vector-layer-fields/
 layer = QgsVectorLayer(fullpath)
 layer.dataProvider().addAttributes([QgsField(newfieldname, QVariant.Date)])
 layer.updateFields()
 
 #Update each feature with date https://gis.stackexchange.com/questions/381174/setting-all-the-values-in-a-attribute-field-to-the-same-value-with-pyqgis)
 attr_map = {}
 field_index = layer.fields().indexFromName(newfieldname)
 for f in layer.getFeatures():
 attr_map[f.id()] = {field_index: newdatename}
 layer.dataProvider().changeAttributeValues(attr_map)`

• Spacedman: If you use the attribute table dialog and create a new field using the expression base_file_name(layer_property(@layer_id,'source')) you will get that. Not sure how to repeat that over 75 layers though. Note this requires the shapefiles to be loaded as layers to QGIS - have you got that?
• Juanjo Valero: @BERA , Thanks a mill, both are working: For a date fieldtype and For a string field.

Answer 1

You can use pyqgis.

For a date fieldtype:

import os, datetime
shapefolder = r'C:\GIS\data\folder' #Where you have your 75 shapefiles (and no other shapefiles, including in any subdirectories!)
newfieldname = 'fecha'
for root, folder, files in os.walk(shapefolder):
 #Find the shapefile
 for file in files:
 fullpath = os.path.join(root,file)
 if os.path.isfile(fullpath) and fullpath.endswith('.shp'):
 print(fullpath)
 #Extract numbers from filename
 datename = ''.join([num for num in file if num.isdigit()])
 #Create a datetime object and convert to string in format 'YYYY-MM-DD', which is what a shapefile wants
 dt = datetime.datetime.strptime(datename, '%Y%m%d')
 newdatename = dt.strftime('%Y-%m-%d')
 print(datename)
 #Add the field https://opensourceoptions.com/blog/pyqgis-adding-and-deleting-vector-layer-fields/
 layer = QgsVectorLayer(fullpath)
 layer.dataProvider().addAttributes([QgsField(newfieldname, QVariant.Date)])
 layer.updateFields()
 
 #Update each feature with date https://gis.stackexchange.com/questions/381174/setting-all-the-values-in-a-attribute-field-to-the-same-value-with-pyqgis)
 attr_map = {}
 field_index = layer.fields().indexFromName(newfieldname)
 for f in layer.getFeatures():
 attr_map[f.id()] = {field_index: newdatename}
 layer.dataProvider().changeAttributeValues(attr_map)

enter image description here

For a string field:

import os
shapefolder = r'C:\GIS\data\testdata\folder'
newfieldname = 'fecha'
for root, folder, files in os.walk(shapefolder):
 #Find the shapefile
 for file in files:
 fullpath = os.path.join(root,file)
 if os.path.isfile(fullpath) and fullpath.endswith('.shp'):
 print(fullpath)
 
 #Extract numbers from filename
 datestr = ''.join([num for num in file if num.isdigit()])
 print(datestr)
 
 #Add the field
 layer = QgsVectorLayer(fullpath)
 layer.dataProvider().addAttributes([QgsField(name=newfieldname, type=QVariant.String, len=10)])
 layer.updateFields()
 
 #Update each feature with date (in a fast way using an attribute map: https://gis.stackexchange.com/questions/381174/setting-all-the-values-in-a-attribute-field-to-the-same-value-with-pyqgis)
 attr_map = {}
 field_index = layer.fields().indexFromName(newfieldname)
 for f in layer.getFeatures():
 attr_map[f.id()] = {field_index: datestr}
 layer.dataProvider().changeAttributeValues(attr_map)