Executing services methods using transaction, implementation of issue #91

README.md

@@ -96,6 +96,56 @@ todos
 
 You can run this example by using `node server` and going to [localhost:8080/todos](http://localhost:8080/todos). You should see an empty array. That's because you don't have any Todos yet but you now have full CRUD for your new todos service!
 
+# Transaction Support
+A example of using the transaction hooks:
+```javascript
+// A common hooks file
+import { hooks } from 'feathers-knex';
+
+const { transaction } = hooks;
+
+const logger = require('./hooks/logger');
+
+module.exports = {
+  before: {
+    all: [transaction.start({ dbServiceName: 'knexClient' })],
+    find: [],
+    get: [],
+    create: [],
+    update: [],
+    patch: [],
+    remove: []
+  },
+
+  after: {
+    all: [logger(), transaction.end()],
+    find: [],
+    get: [],
+    create: [],
+    update: [],
+    patch: [],
+    remove: []
+  },
+
+  error: {
+    all: [transaction.rollback(), logger()],
+    find: [],
+    get: [],
+    create: [],
+    update: [],
+    patch: [],
+    remove: []
+  }
+};
+```
+
+To use the transactions feature, you must ensure that the three hooks (start, commit and rollback) are being used.
+
+At the start of any request, a new transaction will be started. All the changes made during the request to the services that are using the `feathers-knex` will use the transaction. At the end of the request, if sucessful, the changes will be commited. If an error occurs, the changes will be forfeit, all the `creates`, `patches`, `updates` and `deletes` are not going to be commited.
+
+The object that contains `transaction` is stored in the `params.transaction` of each request. If you must extend the `feathers-knex` service, use the `params.transaction.trx` to make your database calls, or simply call the method `this.db(params)` inside a class that extends de `feathers-knex` service.
+
+
 ## License
 
 Copyright (c) 2016

src/hooks.js

@@ -0,0 +1,50 @@
+const debug = require('debug')('feathers-knex-transaction');
+
+const start = (options) => {
+  const { dbServiceName } = options;
+  debug('started transaction system with %s service', dbServiceName);
+  return (hook) =>
+    new Promise(resolve =>
+      hook.app.get(dbServiceName).transaction(trx => {
+        const id = Date.now();
+        hook.params.transaction = {
+          trx,
+          id
+        };
+        debug('started a new transaction %s', id);
+        return resolve(hook);
+      })
+    );
+};
+
+const end = (options) => {
+  return (hook) => {
+    if (hook.params.transaction) {
+      const { trx, id } = hook.params.transaction;
+      return trx.commit()
+        .then(() => debug('finished transaction %s with success', id))
+        .then(hook);
+    }
+    return hook;
+  };
+};
+
+const rollback = (options) => {
+  return (hook) => {
+    if (hook.params.transaction) {
+      const { trx, id } = hook.params.transaction;
+      return trx.rollback()
+        .then(() => debug('rolling back transaction %s', id))
+        .then(hook);
+    }
+    return hook;
+  };
+};
+
+export default {
+  transaction: {
+    start,
+    end,
+    rollback
+  }
+};

src/index.js

@@ -3,6 +3,7 @@ import filter from 'feathers-query-filters';
 import isPlainObject from 'is-plain-object';
 import { errors } from 'feathers-errors';
 import errorHandler from './error-handler';
+import hooks from './hooks';
 
 const debug = require('debug')('feathers-knex');
 
@@ -45,7 +46,12 @@ class Service {
 
   // NOTE (EK): We need this method so that we return a new query
   // instance each time, otherwise it will reuse the same query.
-  db () {
+  db (params = {}) {
+    if (params.transaction) {
+      const { trx, id } = params.transaction;
+      debug('ran %s with transaction %s', this.table, id);
+      return trx(this.table);
+    }
     return this.knex(this.table);
   }
 
@@ -99,13 +105,13 @@ class Service {
     });
   }
 
-  createQuery (paramsQuery = {}) {
-    const { filters, query } = filter(paramsQuery);
-    let q = this.db().select([`${this.table}.*`]);
+  createQuery (params = {}) {
+    const { filters, query } = filter(params.query || {});
+    let q = this.db(params).select([`${this.table}.*`]);
 
     // $select uses a specific find syntax, so it has to come first.
     if (filters.$select) {
-      q = this.db().select(...filters.$select.concat(`${this.table}.${this.id}`));
+      q = this.db(params).select(...filters.$select.concat(`${this.table}.${this.id}`));
     }
 
     // build up the knex query out of the query params
@@ -123,7 +129,7 @@ class Service {
 
   _find (params, count, getFilter = filter) {
     const { filters, query } = getFilter(params.query || {});
-    const q = params.knex || this.createQuery(params.query);
+    const q = params.knex || this.createQuery(params);
 
     // Handle $limit
     if (filters.$limit) {
@@ -158,7 +164,7 @@ class Service {
     }
 
     if (count) {
-      let countQuery = this.db().count(`${this.id} as total`);
+      let countQuery = this.db(params).count(`${this.id} as total`);
 
       this.knexify(countQuery, query);
 
@@ -201,7 +207,7 @@ class Service {
   }
 
   _create (data, params) {
-    return this.db().insert(data, this.id).then(rows => {
+    return this.db(params).insert(data, this.id).then(rows => {
       const id = typeof data[this.id] !== 'undefined' ? data[this.id] : rows[0];
       return this._get(id, params);
     }).catch(errorHandler);
@@ -230,7 +236,7 @@ class Service {
       query[this.id] = id;
     }
 
-    let q = this.db();
+    let q = this.db(params);
 
     this.knexify(q, query);
 
@@ -286,7 +292,7 @@ class Service {
       // NOTE (EK): Delete id field so we don't update it
       delete newObject[this.id];
 
-      return this.db().where(this.id, id).update(newObject).then(() => {
+      return this.db(params).where(this.id, id).update(newObject).then(() => {
         // NOTE (EK): Restore the id field so we can return it to the client
         newObject[this.id] = id;
         return newObject;
@@ -305,7 +311,7 @@ class Service {
 
     return this._find(params).then(page => {
       const items = page.data;
-      const query = this.db();
+      const query = this.db(params);
 
       this.knexify(query, params.query);
 
@@ -328,4 +334,5 @@ export default function init (options) {
   return new Service(options);
 }
 
+init.hooks = hooks;
 init.Service = Service;