Merge pull request #33 from Sharaal/Support-Migrations-#32

Support Migrations #32

README.md

@@ -117,6 +117,12 @@ await sql.query(
 )
 ```
 
+## Migrations
+
+There is also a migrations support to ensure the database is always in the latest schema in all environments. To use this it's needed to create migration files and executing the `migrate` command on every deploy.
+
+Details for these can be found also in the [Wiki -> Migrations](https://github.com/Sharaal/sql-pg/wiki/Migrations).
+
 ## Contact
 
 Found a bug or missing a feature? -> Create a new [Issue](https://github.com/Sharaal/sql-pg/issues)

bin/migrate.js

@@ -0,0 +1,68 @@
+#!/usr/bin/env node
+
+let debug
+try {
+  debug = require('debug')('migrate')
+} catch (e) {
+  debug = console.log
+}
+
+const fs = require('fs')
+const path = require('path')
+
+;(async () => {
+  debug('starting migrations')
+  let client
+  try {
+    client = require(path.join(process.cwd(), 'pg.js'))
+    debug('use the projects `pg.js` to connect to the database')
+  } catch (e) {
+    const { Client } = require('pg')
+    client = new Client({ connectionString: process.env.DATABASE_URL })
+    debug('use the default to connect to the database')
+  }
+  await client.connect()
+
+  debug('create table "migrations" if not exists')
+  await client.query('CREATE TABLE IF NOT EXISTS migrations (file VARCHAR(255) PRIMARY KEY)')
+
+  debug('select already processed migrations:')
+  const processed = (await client.query('SELECT * FROM migrations')).rows
+    .map(({ file }) => file)
+  debug('%o', processed)
+
+  debug('read directory, filter and sort migrations:')
+  const directory = path.join(process.cwd(), 'migrations')
+
+  const migrations = fs.readdirSync(directory)
+    .filter(file => (file.endsWith('.js') || file.endsWith('.sql')) && !processed.includes(file))
+    .sort((fileA, fileB) => parseInt(fileA, 10) - parseInt(fileB, 10))
+  debug('%o', migrations)
+
+  if (migrations.length === 0) {
+    debug('no unprocessed migrations found, database already up to date')
+  } else {
+    for (const file of migrations) {
+      debug('process migration file: "%s"', file)
+      try {
+        await client.query('BEGIN')
+        if (file.endsWith('.js')) {
+          await require(path.join(directory, file))(client)
+        }
+        if (file.endsWith('.sql')) {
+          await client.query(fs.readFileSync(path.join(directory, file)).toString())
+        }
+        await client.query('INSERT INTO migrations (file) VALUES ($1)', [file])
+        await client.query('COMMIT')
+        debug('file successfully processed')
+      } catch (e) {
+        await client.query('ROLLBACK')
+        debug('error: "%s"', e.message)
+        throw e
+      }
+    }
+    debug('all migrations successfully processed')
+  }
+
+  await client.end()
+})()

package.json

@@ -15,6 +15,9 @@
   "publishConfig": {
     "access": "public"
   },
+  "bin" : {
+    "migrate" : "./bin/migrate.js"
+  },
   "scripts": {
     "lint": "standard",
     "lint:fix": "standard --fix",
@@ -30,10 +33,15 @@
     "sinon": "^7.2.4",
     "standard": "^14.0.0"
   },
+  "peerDependencies": {
+    "debug": "^4.1.1",
+    "pg": "^7.12.1"
+  },
   "directories": {
     "test": "test"
   },
   "files": [
+    "bin/migrate.js",
     "index.js",
     "LICENSE",
     "package.json",