Merge pull request datajoint#912 from dimitri-yatsenko/master

fix the counting of deleted items. Issue datajoint#897

Author: guzman-raphael

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### 0.13.2 -- TBD
 * Bugfix - Explicit calls to `dj.Connection` throw error due to missing `host_input` (#895) PR #907
+* Bugfix - Correct count of deleted items. (#897) PR #912
 
 ### 0.13.1 -- Apr 16, 2021
 * Add `None` as an alias for `IS NULL` comparison in `dict` restrictions (#824) PR #893

datajoint/external.py

@@ -321,10 +321,12 @@ def delete(self, *, delete_external_files=None, limit=None, display_progress=Tru
         themselves are deleted too.
         :param limit: (integer) limit the number of items to delete
         :param display_progress: if True, display progress as files are cleaned up
-        :return: yields
+        :return: if deleting external files, returns errors
         """
         if delete_external_files not in (True, False):
-            raise DataJointError("The delete_external_files argument must be set to either True or False in delete()")
+            raise DataJointError(
+                "The delete_external_files argument must be set to either "
+                "True or False in delete()")
 
         if not delete_external_files:
             self.unused().delete_quick()

datajoint/table.py

@@ -351,10 +351,9 @@ def delete_quick(self, get_count=False):
     def _delete_cascade(self):
         """service function to perform cascading deletes recursively."""
         max_attempts = 50
-        delete_count = 0
         for _ in range(max_attempts):
             try:
-                delete_count += self.delete_quick(get_count=True)
+                delete_count = self.delete_quick(get_count=True)
             except IntegrityError as error:
                 match = foreign_key_error_regexp.match(error.args[0]).groupdict()
                 if "`.`" not in match['child']:  # if schema name missing, use self
@@ -383,7 +382,7 @@ def _delete_cascade(self):
                                                   match['pk_attrs'])))
                 else:
                     child &= self.proj()
-                delete_count += child._delete_cascade()
+                child._delete_cascade()
             else:
                 print("Deleting {count} rows from {table}".format(
                     count=delete_count, table=self.full_table_name))
@@ -399,6 +398,7 @@ def delete(self, transaction=True, safemode=None):
         :param transaction: if True, use the entire delete becomes an atomic transaction.
         :param safemode: If True, prohibit nested transactions and prompt to confirm. Default
             is dj.config['safemode'].
+        :return: number of deleted rows (excluding those from dependent tables)
         """
         safemode = config['safemode'] if safemode is None else safemode
 
@@ -439,6 +439,7 @@ def delete(self, transaction=True, safemode=None):
                     self.connection.cancel_transaction()
                 if safemode:
                     print('Deletes cancelled')
+        return delete_count
 
     def drop_quick(self):
         """
@@ -822,8 +823,11 @@ def __call__(self, event, skip_logging=None):
                 logger.info('could not log event in table ~log')
 
     def delete(self):
-        """bypass interactive prompts and cascading dependencies"""
-        self.delete_quick()
+        """
+        bypass interactive prompts and cascading dependencies
+        :return: number of deleted items
+        """
+        return self.delete_quick(get_count=True)
 
     def drop(self):
         """bypass interactive prompts and cascading dependencies"""

docs-parts/intro/Releases_lang1.rst

@@ -1,6 +1,7 @@
 0.13.2 -- TBD
 -------------
 * Bugfix - Explicit calls to `dj.Connection` throw error due to missing `host_input` (#895) PR #907
+* Bugfix - Correct count of deleted items. (#897) PR #912
 
 0.13.1 -- Apr 16, 2021
 ----------------------

tests/test_foreign_keys.py

@@ -18,7 +18,8 @@ def test_aliased_fk():
     parents = person * parent * link
     parents &= dict(full_name="May K. Hall")
     assert_equal(set(parents.fetch('parent_name')), {'Hanna R. Walters', 'Russel S. James'})
-    person.delete()
+    delete_count = person.delete()
+    assert delete_count == 16
 
 
 def test_describe():