fix for issue 96: deleting a column in sqlite shouldn't delete all indexes

bonus: remove_from_table now removes indexes

docs/changelog.rst

@@ -11,6 +11,7 @@ Fixed bugs
   to :mod:`migrate.exceptions`
 - cleared up test output and improved testing of deprecation warnings.
 - some documentation fixes
+- fixed bug with column dropping in sqlite (issue 96)
 
 0.6 (11.07.2010)
 ---------------------------

migrate/changeset/databases/sqlite.py

@@ -35,11 +35,10 @@ class SQLiteHelper(SQLiteCommon):
             table = self._to_table(column.table)
         table_name = self.preparer.format_table(table)
 
-        # we remove all constraints, indexes so it doesnt recreate them
-        ixbackup = copy(table.indexes)
-        consbackup = copy(table.constraints)
-        table.indexes = set()
-        table.constraints = set()
+        # we remove all indexes so as not to have
+        # problems during copy and re-create
+        for index in table.indexes:
+            index.drop()
 
         self.append('ALTER TABLE %s RENAME TO migration_tmp' % table_name)
         self.execute()
@@ -52,10 +51,6 @@ class SQLiteHelper(SQLiteCommon):
         self.append('DROP TABLE migration_tmp')
         self.execute()
 
-        # restore indexes, constraints
-        table.indexes = ixbackup
-        table.constraints = consbackup
-
 class SQLiteColumnGenerator(SQLiteSchemaGenerator, SQLiteCommon, 
                             ansisql.ANSIColumnGenerator):
     """SQLite ColumnGenerator"""

migrate/changeset/schema.py

@@ -568,9 +568,20 @@ populated with defaults
             self._set_parent(table)
 
     def remove_from_table(self, table, unset_table=True):
-        # TODO: remove indexes, primary keys, constraints, etc
+        # TODO: remove primary keys, constraints, etc
         if unset_table:
             self.table = None
+        to_drop = set()
+        for index in table.indexes:
+            columns = []
+            for col in index.columns:
+                if col.name!=self.name:
+                    columns.append(col)
+            if columns:
+                index.columns=columns
+            else:
+                to_drop.add(index)
+        table.indexes = table.indexes - to_drop
         if table.c.contains_column(self):
             table.c.remove(self)
 

migrate/tests/changeset/test_changeset.py

@@ -299,7 +299,41 @@ class TestAddDropColumn(fixture.DB):
     # TODO: test quoting
     # TODO: test non-autoname constraints
 
+    @fixture.usedb()
+    def test_drop_doesnt_delete_other_indexes(self):
+        # add two indexed columns
+        self.table.drop()
+        self.meta.clear()
+        self.table = Table(
+            self.table_name, self.meta,
+            Column('id', Integer, primary_key=True),
+            Column('d1', String(10), index=True),
+            Column('d2', String(10), index=True),
+            )
+        self.table.create()
 
+        # paranoid check
+        if SQLA_06:
+            self.refresh_table()
+            self.assertEqual(
+                sorted([i.name for i in self.table.indexes]),
+                [u'ix_tmp_adddropcol_d1', u'ix_tmp_adddropcol_d2']
+                )
+            
+        # delete one
+        self.table.c.d2.drop()
+
+        # ensure the other index is still there
+        if SQLA_06:
+            self.refresh_table()
+            self.assertEqual(
+                sorted([i.name for i in self.table.indexes]),
+                [u'ix_tmp_adddropcol_d1']
+                )
+        else:
+            # a crude test for 0.5.x
+            Index('ix_tmp_adddropcol_d1',self.table.c.d1).drop()
+            
 class TestRename(fixture.DB):
     """Tests for table and index rename methods"""
     level = fixture.DB.CONNECT