mayflower

Mayflower

A simple database migration utility for making schema changes, or other one-time modifications, to a SQL Server database. It is a node.js port of the C# SQL Server migrator which Stack Overflow uses.

It's the Mayflower because... you use it to migrate, obviously.

Install

npm install mayflower

Mayflower uses mssql and tedious libraries for SQL Server communication, and supports all operating systems.

Usage

There are both programmatic and commandline interfaces to Mayflower.

Commandline

The commandline interface is relatively self-explanatory. After installing the package in your project, npm places an executable at /project_root/node_modules/.bin/mayflower.

$ ./node_modules/.bin/mayflower --help

  Usage: mayflower [options]

  Options:

    -h, --help               output usage information
    -c, --connection [str]   Connection string to SQL Server Database.
    -d, --directory <dir>    Directory containing migration scripts.
    -f, --force              Forces scripts which have already been applied to be applied again.
    -s, --script [filename]  Specifies only a single script to be run.
    -t, --table [name]       Name of the Migrations history table (default: Migrations).
    -j, --json [filename]    Name of a json file where the connection object.
    -k, --key [key]          The key inside the json file for the connection object (dot notation).
    -p, --preview            Outputs results for migration scripts, but rolls back every transaction.

A directory, plus either 1. a connection string, or 2. a json file and key, must be provided. All other parameters are optional.

Example

/etc/project/config.json

{
  "sqlServer": {
    "myDb": {
      "server": "localhost",
      "database": "database_name",
      "port": 1433,
      "user": "user",
      "password": "password",
      "options": {
        "tdsVersion": "7_4"
      }
    }
  }
}

For legacy purposes, using a connection string instead of an object is also supported:

{
  "sqlServer": {
    "myDb": "SERVER=localhost;PORT=1433;DATABASE=MyDb;UID=me;PWD=mypassword;TDS_VERSION=7.4"
  }
}

migrate.sh

./node_modules/.bin/mayflower -d ./migrations -j /etc/project/config.json -k "sqlServer.myDb"

Programmatic

Constructor

Mayflower(connectionString, migrateDirectory, migrationsTable)

• connectionObject The object or string used to create a connection to the database.
• migrateDirectory The directory where to look for *.sql scripts.
• migrationsTable The name of the table where migration history will be stored (defaults to "Migrations"). This table will be created if it does not already exist.

Migrating

The only method you will likely care about is migrateAll( options, callback )

• options An optional object parameter with the following defaults: { output: true, force: false }
  • output determines whether migrateAll() will execute console.log statements.
  • force If true, previously applied migration scripts will be run again.
  • preview If true, all of the migration scripts run as expected, but the SQL transactions are rolled back, so the changes do not take affect.
• callback A function which accepts two arguments: an Error, and an array of MigrationResults.

Each MigrationResult has the following format:

{
  name: String,        // filename of the .sql script
  skipped: Boolean,    // true indicates the script has been previously applied and was skipped
  runtime: Number,     // number of milliseconds the script required to run
  message: String|null // human readable message
}

For an example, see cli.js.

Additional Methods

There are a few additional public methods which are used internally, but may have limited external usefulness. Review the implementation in lib/mayflower.js for details.

• migrate ( db, options, script, callback ) Migrates only a single script.
  • db A dbConnection obtained from getDbConnection().
  • options Same as the options accepted by migrateAll().
  • script must be a Script object returned from getScript() or getAllScripts().
  • callback signature: (error, MigrationResult)
• getDbConnection ( callback ) Opens a database connection. Callback signature (error, dbConnection)
• getAllScripts ( ) Returns an array of script objects.
• getScript ( name ) Returns a single script object. Name is relative to the migrationDirectory which the Mayflower object was constructed with.
• getOutstandingMigrations ( callback ) Gets a list of un-applied migrations. Callback signature (error, scripts) where scripts is an array of Script objects.

Script objects contain name, hash, and commands properties where name and hash are strings, and commands is an array of SQL strings.