Various fixes for data migrations

* Add unique index for `Migration`s
* Fix proper use of `next` callback. First argument is potential error.
* Update migration template

backend/package.json

@@ -4,8 +4,10 @@
   "description": "GraphQL Backend for Human Connection",
   "main": "src/index.js",
   "scripts": {
-    "build": "babel src/ -d dist/ --copy-files",
+    "__migrate": "migrate --compiler 'js:@babel/register' --migrations-dir ./src/db/migrations",
+    "prod:migrate": "migrate --migrations-dir ./dist/db/migrations --store ./dist/db/migrate/store.js",
     "start": "node dist/",
+    "build": "babel src/ -d dist/ --copy-files",
     "dev": "nodemon --exec babel-node src/ -e js,gql",
     "dev:debug": "nodemon --exec babel-node --inspect=0.0.0.0:9229 src/ -e js,gql",
     "lint": "eslint src --config .eslintrc.js",
@@ -13,10 +15,8 @@
     "db:clean": "babel-node src/db/clean.js",
     "db:reset": "yarn run db:clean",
     "db:seed": "babel-node src/db/seed.js",
-    "__migrate": "migrate --compiler 'js:@babel/register' --migrations-dir ./src/db/migrations",
     "db:migrate": "yarn run __migrate --store ./src/db/migrate/store.js",
-    "db:migrate:create": "yarn run __migrate --template-file ./src/db/migrate/template.js create",
-    "production:db:migrate": "migrate --migrations-dir ./dist/db/migrations --store ./dist/db/migrate/store.js"
+    "db:migrate:create": "yarn run __migrate --template-file ./src/db/migrate/template.js create"
   },
   "author": "Human Connection gGmbH",
   "license": "MIT",

backend/src/db/migrate/store.js

@@ -1,32 +1,36 @@
 import { getDriver, getNeode } from '../../db/neo4j'
 
 class Store {
-  async init(fn) {
+  async init(next) {
     const neode = getNeode()
     const { driver } = neode
     const session = driver.session()
     // eslint-disable-next-line no-console
     const writeTxResultPromise = session.writeTransaction(async txc => {
       await txc.run('CALL apoc.schema.assert({},{},true)') // drop all indices
-      return Promise.all([
-        'CALL db.index.fulltext.createNodeIndex("post_fulltext_search",["Post"],["title", "content"])',
-        'CALL db.index.fulltext.createNodeIndex("user_fulltext_search",["User"],["name", "slug"])'
-      ].map(statement => txc.run(statement)))
+      return Promise.all(
+        [
+          'CALL db.index.fulltext.createNodeIndex("post_fulltext_search",["Post"],["title", "content"])',
+          'CALL db.index.fulltext.createNodeIndex("user_fulltext_search",["User"],["name", "slug"])',
+        ].map(statement => txc.run(statement)),
+      )
     })
     try {
       await writeTxResultPromise
       await getNeode().schema.install()
+      // eslint-disable-next-line no-console
       console.log('Successfully created database indices and constraints!')
+      next()
     } catch (error) {
       console.log(error) // eslint-disable-line no-console
+      next(error, null)
     } finally {
       session.close()
       driver.close()
-      fn()
     }
   }
 
-  async load(fn) {
+  async load(next) {
     const driver = getDriver()
     const session = driver.session()
     const readTxResultPromise = session.readTransaction(async txc => {
@@ -42,18 +46,19 @@ class Store {
         console.log(
           "No migrations found in database. If it's the first time you run migrations, then this is normal.",
         )
-        return fn(null, {})
+        return next(null, {})
       }
       const [{ title: lastRun }] = migrations
-      fn(null, { lastRun, migrations })
+      next(null, { lastRun, migrations })
     } catch (error) {
       console.log(error) // eslint-disable-line no-console
+      next(error)
     } finally {
       session.close()
     }
   }
 
-  async save(set, fn) {
+  async save(set, next) {
     const driver = getDriver()
     const session = driver.session()
     const { migrations } = set
@@ -70,11 +75,12 @@ class Store {
     })
     try {
       await writeTxResultPromise
+      next()
     } catch (error) {
       console.log(error) // eslint-disable-line no-console
+      next(error)
     } finally {
       session.close()
-      fn()
     }
   }
 }

backend/src/db/migrate/template.js

@@ -1,7 +1,31 @@
+import { getDriver } from '../../db/neo4j'
+
+export const description = ''
+
 export function up(next) {
-  next()
+  const driver = getDriver()
+  const session = driver.session()
+  try {
+    // Implement your migration here.
+    next()
+  } catch (err) {
+    next(err)
+  } finally {
+    session.close()
+    driver.close()
+  }
 }
 
 export function down(next) {
-  next()
+  const driver = getDriver()
+  const session = driver.session()
+  try {
+    // Rollback your migration here.
+    next()
+  } catch (err) {
+    next(err)
+  } finally {
+    session.close()
+    driver.close()
+  }
 }

backend/src/db/migrations/1579387929122-merge_duplicate_user_accounts.js

@@ -74,11 +74,11 @@ export function up(next) {
         next()
       },
       error: error => {
-        throw new Error(error)
+        next(new Error(error), null)
       },
     })
 }
 
-export function down() {
-  throw new Error('Irreversible migration')
+export function down(next) {
+  next(new Error('Irreversible migration'))
 }

backend/src/models/Migration.js

@@ -0,0 +1,5 @@
+export default {
+  title: { type: 'string', primary: true, token: true },
+  description: { type: 'string' },
+  timestamp: { type: 'number', unique: true },
+}

backend/src/models/index.js

@@ -13,4 +13,5 @@ export default {
   Location: require('./Location.js').default,
   Donations: require('./Donations.js').default,
   Report: require('./Report.js').default,
+  Migration: require('./Migration.js').default,
 }