Modified the migration function to to automatically detect the the fo…

…reign keys based on the signature.

It supports also sqlite using batch migrations

caravel/migrations/versions/1226819ee0e3_fix_wrong_constraint_on_table_columns.py

@@ -13,12 +13,38 @@
 from alembic import op
 import sqlalchemy as sa
 
+naming_convention = {
+    "fk":
+    "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
+}
+
+def find_constraint_name(upgrade = True):
+    __table = 'columns'
+    __cols = {'column_name'} if upgrade else {'datasource_name'}
+    __referenced = 'datasources'
+    __ref_cols = {'datasource_name'} if upgrade else {'column_name'}
+
+    engine = op.get_bind().engine
+    m = sa.MetaData({})
+    t=sa.Table(__table,m, autoload=True, autoload_with=engine)
+
+    for fk in t.foreign_key_constraints:
+        if fk.referred_table.name == __referenced and \
+            set(fk.column_keys) == __cols:
+            return fk.name
+    return None
 
 def upgrade():
-    op.drop_constraint('columns_ibfk_1', 'columns', type_="foreignkey")
-    op.create_foreign_key('columns_ibfk_1', 'columns', 'datasources', ['datasource_name'], ['datasource_name'])
-
+    constraint = find_constraint_name() or 'fk_columns_column_name_datasources'
+    with op.batch_alter_table("columns", 
+        naming_convention=naming_convention) as batch_op:
+        batch_op.drop_constraint(constraint, type_="foreignkey")
+        batch_op.create_foreign_key('fk_columns_datasource_name_datasources', 'datasources', ['datasource_name'], ['datasource_name'])
 
 def downgrade():
-    op.drop_constraint('columns_ibfk_1', 'columns', type_="foreignkey")
-    op.create_foreign_key('columns_ibfk_1', 'columns', 'datasources', ['columns'], ['datasource_name'])
+    constraint = find_constraint_name(False) or 'fk_columns_datasource_name_datasources'
+    with op.batch_alter_table("columns", 
+        naming_convention=naming_convention) as batch_op:
+        batch_op.drop_constraint(constraint, type_="foreignkey")
+        batch_op.create_foreign_key('fk_columns_column_name_datasources', 'datasources', ['column_name'], ['datasource_name'])
+