python的OGR库获取geometry属性返回None，feature.geometry()

如下代码，如果你去百度谷歌，多数是这么获取geometry属性。实际上一直返回None

def create_data_source(gdbFile, **kwargs):
    gdal.SetConfigOption("GDAL_FILENAME_IS_UTF8", "YES")
    driver = ogr.GetDriverByName("FileGDB")
    if os.path.exists(gdbFile):
        data_source = driver.Open(gdbFile, 1)
    else:
        data_source = driver.CreateDataSource(gdbFile)
    return data_source
    
data_source = create_data_source('C:\xxx.gdb')    
layer = data_source.GetLayerByName(layerName)
feature = ogr.Feature(layer.GetLayerDefn())
# geom的值为None
geom = feature.geometry()

    

修改代码：
这时候会发现，geom的值是一个Geometry对象

def create_data_source(gdbFile, **kwargs):
    gdal.SetConfigOption("GDAL_FILENAME_IS_UTF8", "YES")
    driver = ogr.GetDriverByName("FileGDB")
    if os.path.exists(gdbFile):
        data_source = driver.Open(gdbFile, 1)
    else:
        data_source = driver.CreateDataSource(gdbFile)
    return data_source
    
data_source = create_data_source('C:\xxx.gdb')    
layer = data_source.GetLayerByName(layerName)
nextLayer = layer.GetNextFeature()
while nextLayer:
	geom = nextLayer.geometry()