415 lines
14 KiB
Python
415 lines
14 KiB
Python
#!/usr/bin/env python3
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"""
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Database migration tool for MongoDB and PostgreSQL.
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Generates and applies schema migrations with rollback support.
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"""
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import argparse
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import json
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import os
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import sys
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from dataclasses import dataclass
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from datetime import datetime
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from pathlib import Path
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from typing import Any, Dict, List, Optional
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try:
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from pymongo import MongoClient
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MONGO_AVAILABLE = True
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except ImportError:
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MONGO_AVAILABLE = False
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try:
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import psycopg2
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from psycopg2 import sql
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POSTGRES_AVAILABLE = True
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except ImportError:
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POSTGRES_AVAILABLE = False
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@dataclass
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class Migration:
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"""Represents a database migration."""
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id: str
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name: str
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timestamp: datetime
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database_type: str
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up_sql: Optional[str] = None
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down_sql: Optional[str] = None
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mongodb_operations: Optional[List[Dict[str, Any]]] = None
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applied: bool = False
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class MigrationManager:
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"""Manages database migrations for MongoDB and PostgreSQL."""
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def __init__(self, db_type: str, connection_string: str, migrations_dir: str = "./migrations"):
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"""
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Initialize migration manager.
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Args:
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db_type: Database type ('mongodb' or 'postgres')
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connection_string: Database connection string
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migrations_dir: Directory to store migration files
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"""
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self.db_type = db_type.lower()
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self.connection_string = connection_string
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self.migrations_dir = Path(migrations_dir)
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self.migrations_dir.mkdir(exist_ok=True)
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self.client = None
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self.db = None
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self.conn = None
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def connect(self) -> bool:
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"""
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Connect to database.
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Returns:
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True if connection successful, False otherwise
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"""
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try:
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if self.db_type == "mongodb":
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if not MONGO_AVAILABLE:
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print("Error: pymongo not installed")
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return False
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self.client = MongoClient(self.connection_string)
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self.db = self.client.get_default_database()
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# Test connection
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self.client.server_info()
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return True
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elif self.db_type == "postgres":
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if not POSTGRES_AVAILABLE:
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print("Error: psycopg2 not installed")
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return False
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self.conn = psycopg2.connect(self.connection_string)
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return True
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else:
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print(f"Error: Unsupported database type: {self.db_type}")
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return False
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except Exception as e:
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print(f"Connection error: {e}")
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return False
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def disconnect(self):
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"""Disconnect from database."""
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try:
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if self.client:
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self.client.close()
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if self.conn:
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self.conn.close()
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except Exception as e:
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print(f"Disconnect error: {e}")
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def _ensure_migrations_table(self):
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"""Create migrations tracking table/collection if not exists."""
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if self.db_type == "mongodb":
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# MongoDB creates collection automatically
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pass
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elif self.db_type == "postgres":
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with self.conn.cursor() as cur:
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cur.execute("""
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CREATE TABLE IF NOT EXISTS migrations (
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id VARCHAR(255) PRIMARY KEY,
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name VARCHAR(255) NOT NULL,
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applied_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
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)
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""")
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self.conn.commit()
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def generate_migration(self, name: str, dry_run: bool = False) -> Optional[Migration]:
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"""
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Generate new migration file.
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Args:
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name: Migration name
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dry_run: If True, only show what would be generated
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Returns:
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Migration object if successful, None otherwise
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"""
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timestamp = datetime.now()
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migration_id = timestamp.strftime("%Y%m%d%H%M%S")
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filename = f"{migration_id}_{name}.json"
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filepath = self.migrations_dir / filename
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migration = Migration(
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id=migration_id,
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name=name,
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timestamp=timestamp,
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database_type=self.db_type
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)
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if self.db_type == "mongodb":
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migration.mongodb_operations = [
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{
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"operation": "createIndex",
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"collection": "example_collection",
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"index": {"field": 1},
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"options": {}
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}
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]
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elif self.db_type == "postgres":
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migration.up_sql = "-- Add your SQL here\n"
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migration.down_sql = "-- Add rollback SQL here\n"
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migration_data = {
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"id": migration.id,
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"name": migration.name,
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"timestamp": migration.timestamp.isoformat(),
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"database_type": migration.database_type,
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"up_sql": migration.up_sql,
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"down_sql": migration.down_sql,
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"mongodb_operations": migration.mongodb_operations
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}
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if dry_run:
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print(f"Would create: {filepath}")
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print(json.dumps(migration_data, indent=2))
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return migration
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try:
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with open(filepath, "w") as f:
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json.dump(migration_data, f, indent=2)
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print(f"Created migration: {filepath}")
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return migration
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except Exception as e:
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print(f"Error creating migration: {e}")
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return None
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def get_pending_migrations(self) -> List[Migration]:
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"""
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Get list of pending migrations.
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Returns:
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List of pending Migration objects
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"""
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# Get applied migrations
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applied_ids = set()
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try:
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if self.db_type == "mongodb":
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applied_ids = {
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doc["id"] for doc in self.db.migrations.find({}, {"id": 1})
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}
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elif self.db_type == "postgres":
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with self.conn.cursor() as cur:
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cur.execute("SELECT id FROM migrations")
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applied_ids = {row[0] for row in cur.fetchall()}
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except Exception as e:
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print(f"Error reading applied migrations: {e}")
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# Get all migration files
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pending = []
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for filepath in sorted(self.migrations_dir.glob("*.json")):
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try:
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with open(filepath) as f:
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data = json.load(f)
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if data["id"] not in applied_ids:
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migration = Migration(
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id=data["id"],
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name=data["name"],
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timestamp=datetime.fromisoformat(data["timestamp"]),
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database_type=data["database_type"],
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up_sql=data.get("up_sql"),
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down_sql=data.get("down_sql"),
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mongodb_operations=data.get("mongodb_operations")
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)
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pending.append(migration)
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except Exception as e:
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print(f"Error reading {filepath}: {e}")
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return pending
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def apply_migration(self, migration: Migration, dry_run: bool = False) -> bool:
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"""
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Apply migration.
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Args:
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migration: Migration to apply
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dry_run: If True, only show what would be executed
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Returns:
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True if successful, False otherwise
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"""
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print(f"Applying migration: {migration.id} - {migration.name}")
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if dry_run:
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if self.db_type == "mongodb":
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print("MongoDB operations:")
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print(json.dumps(migration.mongodb_operations, indent=2))
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elif self.db_type == "postgres":
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print("SQL to execute:")
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print(migration.up_sql)
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return True
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try:
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if self.db_type == "mongodb":
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for op in migration.mongodb_operations or []:
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if op["operation"] == "createIndex":
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self.db[op["collection"]].create_index(
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list(op["index"].items()),
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**op.get("options", {})
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)
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# Record migration
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self.db.migrations.insert_one({
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"id": migration.id,
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"name": migration.name,
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"applied_at": datetime.now()
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})
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elif self.db_type == "postgres":
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with self.conn.cursor() as cur:
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cur.execute(migration.up_sql)
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# Record migration
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cur.execute(
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"INSERT INTO migrations (id, name) VALUES (%s, %s)",
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(migration.id, migration.name)
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)
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self.conn.commit()
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print(f"✓ Applied: {migration.id}")
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return True
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except Exception as e:
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print(f"✗ Error applying migration: {e}")
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if self.conn:
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self.conn.rollback()
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return False
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def rollback_migration(self, migration_id: str, dry_run: bool = False) -> bool:
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"""
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Rollback migration.
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Args:
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migration_id: Migration ID to rollback
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dry_run: If True, only show what would be executed
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Returns:
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True if successful, False otherwise
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"""
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# Find migration file
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migration_file = None
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for filepath in self.migrations_dir.glob(f"{migration_id}_*.json"):
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migration_file = filepath
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break
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if not migration_file:
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print(f"Migration not found: {migration_id}")
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return False
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try:
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with open(migration_file) as f:
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data = json.load(f)
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print(f"Rolling back: {migration_id} - {data['name']}")
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if dry_run:
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if self.db_type == "postgres":
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print("SQL to execute:")
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print(data.get("down_sql", "-- No rollback defined"))
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return True
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if self.db_type == "postgres" and data.get("down_sql"):
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with self.conn.cursor() as cur:
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cur.execute(data["down_sql"])
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cur.execute("DELETE FROM migrations WHERE id = %s", (migration_id,))
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self.conn.commit()
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elif self.db_type == "mongodb":
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self.db.migrations.delete_one({"id": migration_id})
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print(f"✓ Rolled back: {migration_id}")
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return True
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except Exception as e:
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print(f"✗ Error rolling back: {e}")
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if self.conn:
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self.conn.rollback()
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return False
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def main():
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"""Main entry point."""
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parser = argparse.ArgumentParser(description="Database migration tool")
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parser.add_argument("--db", required=True, choices=["mongodb", "postgres"],
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help="Database type")
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parser.add_argument("--uri", help="Database connection string")
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parser.add_argument("--migrations-dir", default="./migrations",
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help="Migrations directory")
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subparsers = parser.add_subparsers(dest="command", required=True)
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# Generate command
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gen_parser = subparsers.add_parser("generate", help="Generate new migration")
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gen_parser.add_argument("name", help="Migration name")
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gen_parser.add_argument("--dry-run", action="store_true",
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help="Show what would be generated")
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# Apply command
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apply_parser = subparsers.add_parser("apply", help="Apply pending migrations")
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apply_parser.add_argument("--dry-run", action="store_true",
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help="Show what would be executed")
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# Rollback command
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rollback_parser = subparsers.add_parser("rollback", help="Rollback migration")
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rollback_parser.add_argument("id", help="Migration ID to rollback")
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rollback_parser.add_argument("--dry-run", action="store_true",
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help="Show what would be executed")
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# Status command
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subparsers.add_parser("status", help="Show migration status")
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args = parser.parse_args()
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# For generate, we don't need connection
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if args.command == "generate":
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manager = MigrationManager(args.db, "", args.migrations_dir)
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migration = manager.generate_migration(args.name, args.dry_run)
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sys.exit(0 if migration else 1)
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# Other commands need connection
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if not args.uri:
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print("Error: --uri required for this command")
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sys.exit(1)
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manager = MigrationManager(args.db, args.uri, args.migrations_dir)
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if not manager.connect():
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sys.exit(1)
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try:
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manager._ensure_migrations_table()
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if args.command == "status":
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pending = manager.get_pending_migrations()
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print(f"Pending migrations: {len(pending)}")
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for migration in pending:
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print(f" {migration.id} - {migration.name}")
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elif args.command == "apply":
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pending = manager.get_pending_migrations()
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if not pending:
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print("No pending migrations")
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else:
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for migration in pending:
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if not manager.apply_migration(migration, args.dry_run):
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sys.exit(1)
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elif args.command == "rollback":
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if not manager.rollback_migration(args.id, args.dry_run):
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sys.exit(1)
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finally:
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manager.disconnect()
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if __name__ == "__main__":
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main()
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