db-migrate

Database migration framework for node.js

Installation

$ npm install db-migrate

Supported Databases

• Mysql (https://github.com/felixge/node-mysql)
• PostgreSQL (https://github.com/brianc/node-postgres)
• sqlite3 (https://github.com/developmentseed/node-sqlite3)

Usage

Usage: db-migrate [up|down|create] migrationName [options]

Options:
  --env, -e             The environment to run the migrations under.    [default: "dev"]
  --migrations-dir, -m  The directory containing your migration files.  [default: "./migrations"]
  --count, -c           Max number of migrations to run.
  --dry-run             Prints the SQL but doesn't run it.              [boolean]
  --verbose, -v         Verbose mode.                                   [default: false]
  --config              Location of the database.json file.             [default: "./database.json"]

Creating Migrations

To create a migration, execute db-migrate create with a title. node-db-migrate will create a node module within ./migrations/ which contains the following two exports:

exports.up = function (db, callback) {
  callback();
};

exports.down = function (callback) {
  callback();
};

All you have to do is populate these, invoking callback() when complete, and you are ready to migrate!

For example:

$ db-migrate create add-pets
$ db-migrate create add-owners

The first call creates ./migrations/20111219120000-add-pets.js, which we can populate:

exports.up = function (db, callback) {
  db.createTable('pets', {
    id: { type: 'int', primaryKey: true },
    name: 'string'
  }, callback);
};

exports.down = function (db, callback) {
  db.dropTable('pets', callback);
};

The second creates ./migrations/20111219120005-add-owners.js, which we can populate:

exports.up = function (db, callback) {
  db.createTable('owners', {
    id: { type: 'int', primaryKey: true },
    name: 'string'
  }, callback);
};

exports.down = function (db, callback) {
  db.dropTable('owners', callback);
};

Executing multiple statements against the database within a single migration requires a bit more care. You can either nest the migrations like:

exports.up = function (db, callback) {
  db.createTable('pets', {
    id: { type: 'int', primaryKey: true },
    name: 'string'
  }, createOwners);

  function createOwners(err) {
    if (err) { callback(err); return; }
    db.createTable('owners', {
      id: { type: 'int', primaryKey: true },
      name: 'string'
    }, callback);
  }
};

exports.down = function (db, callback) {
  db.dropTable('pets', function(err) {
    if (err) { callback(err); return; }
    db.dropTable('owners', callback); 
  });
};

or use the async library to simplify things a bit, such as:

var async = require('async');

exports.up = function (db, callback) {
  async.series([
    db.createTable.bind(db, 'pets', {
      id: { type: 'int', primaryKey: true },
      name: 'string'
    }),
    db.createTable.bind(db, 'owners', {
      id: { type: 'int', primaryKey: true },
      name: 'string'
    });
  ], callback);
};

exports.down = function (db, callback) {
  async.series([
    db.dropTable.bind(db, 'pets'),
    db.dropTable.bind(db, 'owners')
  ], callback);
};

Running Migrations

When first running the migrations, all will be executed in sequence. A table named migrations will also be created in your database to track which migrations have been applied.

  $ db-migrate up
  [INFO] Processed migration 20111219120000-add-pets
  [INFO] Processed migration 20111219120005-add-owners
  [INFO] Done

Subsequent attempts to run these migrations will result in the following output

  $ db-migrate up
  [INFO] No migrations to run
  [INFO] Done

If we were to create another migration using db-migrate create, and then execute migrations again, we would execute only those not previously executed:

  $ db-migrate up
  [INFO] Processed migration 20111220120210-add-kennels
  [INFO] Done

You can also run migrations incrementally by specifying a date substring. The example below will run all migrations created on or before December 19, 2011:

  $ db-migrate up 20111219
  [INFO] Processed migration 20111219120000-add-pets
  [INFO] Processed migration 20111219120005-add-owners
  [INFO] Done

You can also run a specific number of migrations with the -c option:

  $ db-migrate up -c 1
  [INFO] Processed migration 20111219120000-add-pets
  [INFO] Done

All of the down migrations work identically to the up migrations by substituting the word down for up.

Configuration

db-migrate supports the concept of environments. For example, you might have a dev, test, and prod environment where you need to run the migrations at different times. Environment settings are loaded from a database.json file like the one shown below:

{
  "dev": {
    "driver": "sqlite3",
    "filename": "~/dev.db"
  },

  "test": {
    "driver": "sqlite3",
    "filename": ":memory:"
  },

  "prod": {
    "driver": "mysql",
    "user": "root",
    "password": "root"
  },

  "pg": {
    "driver": "pg",
    "user": "test",
    "password": "test",
    "host": "localhost",
    "database": "mydb"
  }
}

You can pass the -e or --env option to db-migrate to select the environment you want to run migrations against. The --config option can be used to specify the path to your database.json file if it's not in the current working directory.

db-migrate up --config config/database.json -e prod

The above will run all migrations that haven't yet been run in the prod environment, grabbing the settings from config/database.json.

Alternatively, for PostgreSQL, you can specify a DATABASE_URL environment variable that will be used in place of the configuration file settings. This is helpful for use with Heroku.

Defaults

Migrations API

Below are examples of all the different migrations supported by db-migrate. Please note that not all migrations are supported by all databases. For example, SQLite does not support dropping columns.

createTable(tableName, columnSpec, callback)

Creates a new table with the specified columns.

Arguments

• tableName - the name of the table to create
• columnSpec - a hash of column definitions
• callback(err) - callback that will be invoked after table creation

Examples

// with no table options
exports.up = function (db, callback) {
  db.createTable('pets', {
    id: { type: 'int', primaryKey: true, autoIncrement: true },
    name: 'string'  // shorthand notation
  }, callback);
}

// with table options
exports.up = function (db, callback) {
  db.createTable('pets', {
    columns: {
      id: { type: 'int', primaryKey: true, autoIncrement: true },
      name: 'string'  // shorthand notation
    },
    ifNotExists: true
  }, callback);
}

Column Specs

The following options are available on column specs

• type - the column data type. Supported types can be found in lib/data_type.js
• length - the column data length, where supported
• primaryKey - true to set the column as a primary key. Compound primary keys are supported by setting the primaryKey option to true on multiple columns
• autoIncrement - true to mark the column as auto incrementing
• notNull - true to mark the column as non-nullable
• unique - true to add unique constraint to the column
• defaultValue - set the column default value

dropTable(tableName, [options,] callback)

Drop a database table

Arguments

• tableName - name of the table to drop
• options - table options
• callback(err) - callback that will be invoked after dropping the table

Table Options

• ifExists - Only drop the table if it already exists

renameTable(tableName, newTableName, callback)

Rename a database table

Arguments

• tableName - existing table name
• options - new table name
• callback(err) - callback that will be invoked after renaming the table

addColumn(tableName, columnName, columnSpec, callback)

Add a column to a database table

Arguments

• tableName - name of table to add a column to
• columnName - name of the column to add
• columnSpec - a hash of column definitions
• callback(err) - callback that will be invoked after adding the column

Column spec is the same as that described in createTable

removeColumn(tableName, columnName, callback)

Remove a column from an existing database table

• tableName - name of table to add a column to
• columnName - name of the column to add
• callback(err) - callback that will be invoked after removing the column

renameColumn(tableName, oldColumnName, newColumnName, callback)

Rename a column

Arguments

• tableName - table containing column to rename
• oldColumnName - existing column name
• newColumnName - new name of the column
• callback(err) - callback that will be invoked after renaming the column

changeColumn(tableName, columnName, columnSpec, callback)

Change the definition of a column

Arguments

• tableName - table containing column to change
• columnName - existing column name
• columnSpec - a hash containing the column spec
• callback(err) - callback that will be invoked after changing the column

addIndex(tableName, indexName, columns, callback)

Add an index

Arguments

• tableName - table to add the index too
• indexName - the name of the index
• columns - an array of column names contained in the index
• callback(err) - callback that will be invoked after adding the index

insert(tableName, columnNameArray, valueArray, callback)

Insert an item into a given column

Arguments

• tableName - table to insert the item into
• columnNameArray - the array existing column names for each item being inserted
• valueArray - the array of values to be inserted into the associated column
• callback(err) - callback that will be invoked once the insert has been completed.

removeIndex([tableName], indexName, callback)

Remove an index

Arguments

• tableName - name of the table that has the index (Required for mySql)
• indexName - the name of the index
• callback(err) - callback that will be invoked after removing the index

runSql(sql, [params,] callback)

Run arbitrary SQL

Arguments

• sql - the SQL query string, possibly with ? replacement parameters
• params - zero or more ? replacement parameters
• callback(err) - callback that will be invoked after executing the SQL

all(sql, [params,] callback)

Execute a select statement

Arguments

• sql - the SQL query string, possibly with ? replacement parameters
• params - zero or more ? replacement parameters
• callback(err, results) - callback that will be invoked after executing the SQL

License

(The MIT License)

Copyright (c) 2011 Near Infinity Corporation

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.