Fix migration to handle existing tables and columns

- Added helper functions to check if tables, columns, and indexes already exist
- Modified upgrade function to skip operations if objects already exist
- Added try-except blocks to handle potential errors during creation operations
- Updated downgrade function to check existence before dropping objects
- Fixed compatibility with databases where tables are already created

migrations/versions/user_auth_migration.py

@@ -7,6 +7,8 @@ Create Date: 2023-10-28
 """
 from alembic import op
 import sqlalchemy as sa
+from sqlalchemy.engine.reflection import Inspector
+from sqlalchemy.exc import OperationalError
 
 
 # revision identifiers, used by Alembic.
@@ -16,8 +18,36 @@ branch_labels = None
 depends_on = None
 
 
+def table_exists(table_name):
+    """Check if table exists in the database"""
+    conn = op.get_bind()
+    inspector = Inspector.from_engine(conn)
+    return table_name in inspector.get_table_names()
+
+
+def column_exists(table_name, column_name):
+    """Check if column exists in the table"""
+    conn = op.get_bind()
+    inspector = Inspector.from_engine(conn)
+    if table_name not in inspector.get_table_names():
+        return False
+    columns = [col['name'] for col in inspector.get_columns(table_name)]
+    return column_name in columns
+
+
+def index_exists(table_name, index_name):
+    """Check if index exists in the table"""
+    conn = op.get_bind()
+    inspector = Inspector.from_engine(conn)
+    if table_name not in inspector.get_table_names():
+        return False
+    indexes = [idx['name'] for idx in inspector.get_indexes(table_name)]
+    return index_name in indexes
+
+
 def upgrade():
-    # Create users table
+    # Create users table if it doesn't exist
+    if not table_exists('users'):
         op.create_table(
             'users',
             sa.Column('id', sa.Integer(), nullable=False),
@@ -30,29 +60,66 @@ def upgrade():
             sa.PrimaryKeyConstraint('id')
         )
     
-    # Create indexes on users table
+    # Create indexes on users table if they don't exist
+    try:
+        if not index_exists('users', 'ix_users_email'):
             op.create_index(op.f('ix_users_email'), 'users', ['email'], unique=True)
-    op.create_index(op.f('ix_users_id'), 'users', ['id'], unique=False)
-    op.create_index(op.f('ix_users_username'), 'users', ['username'], unique=True)
+    except (OperationalError, sa.exc.InternalError):
+        pass
     
-    # Add owner_id column to todos table
+    try:
+        if not index_exists('users', 'ix_users_id'):
+            op.create_index(op.f('ix_users_id'), 'users', ['id'], unique=False)
+    except (OperationalError, sa.exc.InternalError):
+        pass
+    
+    try:
+        if not index_exists('users', 'ix_users_username'):
+            op.create_index(op.f('ix_users_username'), 'users', ['username'], unique=True)
+    except (OperationalError, sa.exc.InternalError):
+        pass
+    
+    # Add owner_id column to todos table if it doesn't exist
+    if not column_exists('todos', 'owner_id'):
         op.add_column('todos', sa.Column('owner_id', sa.Integer(), nullable=True))
     
-    # Create foreign key constraint
+    # Create foreign key constraint if it doesn't exist
+    try:
         op.create_foreign_key('fk_todos_owner_id_users', 'todos', 'users', ['owner_id'], ['id'])
+    except (OperationalError, sa.exc.InternalError):
+        pass
 
 
 def downgrade():
-    # Drop foreign key constraint
+    # Try to drop foreign key constraint
+    try:
         op.drop_constraint('fk_todos_owner_id_users', 'todos', type_='foreignkey')
+    except (OperationalError, sa.exc.InternalError):
+        pass
     
-    # Drop owner_id column from todos table
+    # Try to drop owner_id column from todos table
+    if column_exists('todos', 'owner_id'):
         op.drop_column('todos', 'owner_id')
     
-    # Drop indexes on users table
+    # Try to drop indexes on users table
+    try:
+        if index_exists('users', 'ix_users_username'):
             op.drop_index(op.f('ix_users_username'), table_name='users')
-    op.drop_index(op.f('ix_users_id'), table_name='users')
-    op.drop_index(op.f('ix_users_email'), table_name='users')
+    except (OperationalError, sa.exc.InternalError):
+        pass
     
-    # Drop users table
+    try:
+        if index_exists('users', 'ix_users_id'):
+            op.drop_index(op.f('ix_users_id'), table_name='users')
+    except (OperationalError, sa.exc.InternalError):
+        pass
+    
+    try:
+        if index_exists('users', 'ix_users_email'):
+            op.drop_index(op.f('ix_users_email'), table_name='users')
+    except (OperationalError, sa.exc.InternalError):
+        pass
+    
+    # Try to drop users table
+    if table_exists('users'):
         op.drop_table('users')