feat: support config.Sequelize

Author: dead-horse

README.md

@@ -139,6 +139,21 @@ module.exports = app => {
 }
 ```
 
+### Associate
+
+Define all your associations in `Model.associate()` and egg-sequelize will execute it after all models loaded. See example below.
+
+### Customize Sequelize
+
+By default, egg-sequelize will use sequelize@4, you can cusomize sequelize version by pass sequelize instance with `config.sequelize.Sequelize` like this:
+
+```js
+// config/config.default.js
+exports.sequelize = {
+  sequelize: require('sequelize');
+};
+```
+
 ### Full example
 
 ```js

agent.js

@@ -3,4 +3,3 @@
 module.exports = agent => {
   require('./lib/loader')(agent);
 };
-

config/config.default.js

@@ -7,4 +7,21 @@ exports.sequelize = {
   port: 3306,
   username: 'root',
   password: '',
+
+  // support customize your own Squelize
+  Sequelize: require('sequelize'), // v5 or v3
+
+  // support multi datasources by config.sequelize.datasources
+  // datasources: [
+  //   {
+  //     delegate: 'model', // lood to `app[delegate]`
+  //     baseDir: 'model', // models in `app/${model}`
+  //     // other sequelize configurations
+  //   },
+  //   {
+  //     delegate: 'sequelize', // lood to `app[delegate]`
+  //     baseDir: 'sequelize', // models in `app/${model}`
+  //     // other sequelize configurations
+  //   },
+  // ],
 };

lib/loader.js

@@ -1,9 +1,8 @@
 'use strict';
 
 const path = require('path');
-const Sequelize = require('sequelize');
-const AUTH_RETRIES = Symbol('authenticateRetries');
 const sleep = require('mz-modules/sleep');
+const AUTH_RETRIES = Symbol('authenticateRetries');
 
 module.exports = app => {
   const defaultConfig = {
@@ -21,7 +20,8 @@ module.exports = app => {
   };
 
   const config = app.config.sequelize;
-  app.Sequelize = Sequelize;
+  // support customize sequelize
+  app.Sequelize = config.Sequelize || require('sequelize');
 
   const databases = [];
   if (!config.datasources) {