Fix error when altering Part table that uses "master" keyword

Author: rly

datajoint/user_tables.py

@@ -2,6 +2,7 @@
 Hosts the table tiers, user relations should be derived from.
 """
 
+import inspect
 from .table import Table
 from .autopopulate import AutoPopulate
 from .utils import from_camel_case, ClassProperty
@@ -186,3 +187,16 @@ def drop(self, force=False):
             super().drop()
         else:
             raise DataJointError('Cannot drop a Part directly.  Delete from master instead')
+
+    def alter(self, prompt=True, context=None):
+        """
+        Alter the table definition from self.definition
+        """
+        # map "master" keyword to master table in context
+        if context is None:
+            frame = inspect.currentframe().f_back
+            context = dict(frame.f_globals, **frame.f_locals)
+            del frame
+        if self.master:
+            context['master'] = self.master
+        super().alter(prompt, context)

tests/test_alter.py

@@ -39,3 +39,26 @@ def test_alter():
     restored = schema.connection.query("SHOW CREATE TABLE " + Experiment.full_table_name).fetchone()[1]
     assert_not_equal(altered, restored)
     assert_equal(original, restored)
+
+
+@schema
+class TypeMaster(dj.Manual):
+    definition = """
+    master_id : int
+    """
+
+    class Type(dj.Part):
+        definition = """
+        -> master
+        """
+
+        definition1 = """
+        -> TypeMaster
+        """
+
+def test_alter_part():
+    original = schema.connection.query("SHOW CREATE TABLE " + TypeMaster.Type.full_table_name).fetchone()[1]
+    TypeMaster.Type.definition = Experiment.definition1
+    TypeMaster.Type.alter(prompt=False)
+    altered = schema.connection.query("SHOW CREATE TABLE " + TypeMaster.Type.full_table_name).fetchone()[1]
+    assert_equal(original, altered)