lib/migrate

Migrate

"use strict"; var fs = require('fs'); var path = require('path'); var _ = require('lodash'); var mkdirp = require('mkdirp'); var Promise = require('./promise').Promise;

The new migration we're performing, typically called from the knex.migrate interface on the main knex object. Passes the knex instance performing the migration.

var Migrate = function(instance) { this.knex = instance; }; Migrate.prototype = {

Initializes the migration, taking an optional config object, for things like the tableName.

init: function(config) { if (!this._init) { this.config = _.defaults(config || {}, { extension: 'js', tableName: 'knex_migrations', directory: process.cwd() + '/migrations' }); if (this.config.directory.indexOf('./') === 0) { this.config.directory = path.resolve(process.cwd(), this.config.directory); } this._init = Promise.all([ this.ensureFolder(config), this.ensureTable(config) ]).bind(this); } return this._init; },

Ensures that the proper table has been created, dependent on the migration config settings.

ensureTable: function(config) { var migration = this; return this.knex.schema.hasTable(config.tableName) .then(function(exists) { if (!exists) return migration.createMigrationTable(config.tableName); }); },

Ensures a folder for the migrations exist, dependent on the migration config settings.

ensureFolder: function(config) { return Promise.promisify(fs.stat, fs)(config.directory) .catch(function() { return Promise.promisify(mkdirp)(config.directory); }); },

Create the migration table, if it doesn't already exist.

createMigrationTable: function(tableName) { return this.knex.schema.createTable(tableName, function(t) { t.increments(); t.string('name'); t.integer('batch'); t.dateTime('migration_time'); }); },

Migrates to the latest configuration.

latest: function(config) { return this.init(config) .then(this.migrationData) .tap(validateMigrationList) .spread(function(all, completed) { return this.runBatch(_.difference(all, completed), 'up'); }) .bind(); },

Rollback the last "batch" of migrations that were run.

rollback: function(config) { return this.init(config) .then(this.migrationData) .tap(validateMigrationList) .then(this.getLastBatch) .then(function(migrations) { return this.runBatch(_.pluck(migrations, 'name'), 'down'); }) .bind(); },

Run a batch of current migrations, in sequence.

runBatch: function(migrations, direction) { return Promise.map(migrations, validateMigrationStructure(this)) .bind(this) .then(function(migrations) { return this.latestBatchNumber().then(function(batchNo) { if (direction === 'up') batchNo++; return batchNo; }).then(this.waterfallBatch(migrations, direction)); }); },

Retrieves and returns the current migration version we're on, as a promise. If there aren't any migrations run yet, return "none" as the value for the currentVersion.

currentVersion: function(config) { return this.listCompleted(config).then(function(completed) { var val = _.chain(completed).map(function(value) { return value.split('_')[0]; }).max().value(); return (val === -Infinity ? 'none' : val); }); },

Creates a new migration, with a given name.

make: function(name, config) { if (!name) Promise.rejected(new Error('A name must be specified for the generated migration')); return this.init(config) .then(this.generateStubTemplate) .then(this.writeNewMigration(name)); },

Lists all available migration versions, as a sorted array.

listAll: function(config) { return this.init(config) .then(function() { return Promise.promisify(fs.readdir, fs)(this.config.directory); }) .then(function(migrations) { var ext = this.config.extension; return _.filter(migrations, function (value) { return value.indexOf(ext, value.length - ext.length) !== -1; }).sort(); }); },

Lists all migrations that have been completed for the current db, as an array.

listCompleted: function(config) { return this.init(config) .then(function() { return this.knex(this.config.tableName).orderBy('id').select('name'); }) .then(function(migrations) { return _.pluck(migrations, 'name'); }) .bind(); },

Gets the migration list from the specified migration directory, as well as the list of completed migrations to check what should be run.

migrationData: function() { return Promise.all([ this.listAll(), this.listCompleted() ]); },

Generates the stub template for the current migration, returning a compiled template.

generateStubTemplate: function() { var stubPath = this.config.stub || path.join(__dirname, 'stub', this.config.extension + '.stub'); return Promise.promisify(fs.readFile, fs)(stubPath).then(function(stub) { return _.template(stub.toString(), null, {variable: 'd'}); }); },

Write a new migration to disk, using the config and generated filename, passing any variables given in the config to the template.

writeNewMigration: function(name) { var config = this.config; return function(tmpl) { if (name[0] === '-') name = name.slice(1); var filename = yyyymmddhhmmss() + '_' + name + '.' + config.extension; return Promise.promisify(fs.writeFile, fs)( path.join(config.directory, filename), tmpl(config.variables || {}) ).yield(filename); }; },

Get the last batch of migrations, by name, ordered by insert id in reverse order.

getLastBatch: function() { var knex = this.knex; var tableName = this.config.tableName; return this.knex(tableName) .where('batch', function() { this.select(knex.raw('MAX(batch)')).from(tableName); }) .orderBy('id', 'desc'); },

Returns the latest batch number.

latestBatchNumber: function() { return this.knex(this.config.tableName) .max('batch as batchNo').then(function(obj) { return (obj[0].batchNo || 0); }); },

Runs a batch of migrations in a specified direction, saving the appropriate database information as the migrations are run.

waterfallBatch: function(migrations, direction) { var knex = this.knex; var tableName = this.config.tableName; var current = Promise.fulfilled().bind({failed: false, failedOn: 0}); var log = []; return function(batchNo) { _.each(migrations, function(migration, i) { var name = migration[0]; migration = migration[1];

We're going to run each of the migrations in the current "up"

current = current.then(function() { return migration[direction](knex, Promise); }).then(function() { log.push(name); if (direction === 'up') { return knex(tableName).insert({ name: name, batch: batchNo, migration_time: new Date() }); } if (direction === 'down') { return knex(tableName).where({name: name}).del(); } }); }); return current.yield([batchNo, log]); }; } };

Validates some migrations by requiring and checking for an up and down function, returning an array with the item and migration require.

Validates that migrations are present in the appropriate directories.

function validateMigrationList(all, completed) { var diff = _.difference(completed, all); if (!_.isEmpty(diff)) { throw new Error( 'The migration directory is corrupt, the following files are missing: ' + diff.join(', ') ); } }

Gets the current migration.

var getMigration = function(all, version, config) { var found = _.find(all, function(item) { item.indexOf(version) === 0; }); if (!found) throw new Error('Unable to locate the specified migration ' + version); return path.join(config.directory, found); };

Parse the version, which really only needs to be the timestamp of the migration we wish to migrate to.

var parseVersion = function(version) { if (version !== 'latest') { version = version.slice(0, 14); if (version.length !== 14) { throw new Error('Invalid migration provided'); } } return version; };

Get a date object in the correct format, without requiring a full out library like "moment.js".

var yyyymmddhhmmss = function() { var d = new Date(); return d.getFullYear().toString() + padDate(d.getMonth() + 1) + padDate(d.getDate()) + padDate(d.getHours()) + padDate(d.getMinutes()) + padDate(d.getSeconds()); };

Ensure that we have 2 places for each of the date segments

var padDate = function(segment) { segment = segment.toString(); return segment[1] ? segment : '0' + segment; };

Dasherize the string.

var dasherize = function(str) { return str.replace(/([A-Z])/g, '-$1').replace(/[-_\s]+/g, '-').toLowerCase(); }; module.exports = Migrate;