close netcdf file if exception occurrs during writing

Author: mhidas

ncwriter/template.py

@@ -351,10 +351,15 @@ def to_netcdf(self, outfile, var_args={}, **kwargs):
         if not self.is_dim_consistent():
             raise ValueError("Dimensions.")
 
-        self.ncobj = netCDF4.Dataset(self.outfile, mode='w', **kwargs)
-        self.create_dimensions()
-        self.create_variables(**var_args)
-        self.create_global_attributes()
-        self.ncobj.sync()
-        self.ncobj.close()
+        try:
+            self.ncobj = netCDF4.Dataset(self.outfile, mode='w', **kwargs)
+            self.create_dimensions()
+            self.create_variables(**var_args)
+            self.create_global_attributes()
+            self.ncobj.sync()
+        except Exception:
+            raise
+        finally:
+            self.ncobj.close()
+
         self.ncobj = netCDF4.Dataset(self.outfile, 'a')

test_ncwriter/test_template.py

@@ -225,6 +225,13 @@ def test_fill_values_from_masked_array(self):
         self.assertTrue(dsx[:5].mask.all())
         self.assertTrue((dsx[5:] == x[5:]).all())
 
+    def test_close_file_on_exception(self):
+        template = DatasetTemplate.from_json(TEMPLATE_JSON)
+        self.assertIsNone(template.ncobj)
+        self.assertRaises(ValueError, template.to_netcdf, self.temp_nc_file)
+        self.assertFalse(template.ncobj.isopen())
+
+
 # TODO: add data from multiple numpy arrays
 # e.g. template.add_data(TIME=time_values, TEMP=temp_values, PRES=pres_values)
 # TODO: add data from Pandas dataframe (later...)