经过两天的努力弄清楚为什么我的Sequelize模特没有致力于他们的关系，我已经决定是时候向所有人寻求建议。
这是故事。
我正在使用Postgres（9.4）数据库编写Feathers JS应用程序，并将Sequelize作为驱动程序。我在Feathers Docs中完成了设置，并通过一些哄骗，让我的迁移得以运行。
根据我的理解，必须特别考虑使用Sequelize进行双向关系，因为如果ModelA引用ModelB，则必须已定义ModelB，但如果ModelB 1}}引用ModelA ......好吧，我们遇到了一个依赖循环。
这是因为文档说的依赖循环使用此处描述的方法来定义模型。＆＃34; （好吧，技术上它只是假设＆＃34;使用了这样的结构。而且，我只能发布2个链接，否则我会链接那个吸盘。对不起。）我发现了Feathers demo中的相同结构。
当然，我反映了所有这一切（当然，除非我错过了一个小而重要的细节），但是......仍然没有骰子。
这是我正在看的内容：
'use strict';
module.exports = {
up: function (queryInterface, Sequelize) {
// Make the accounts table if it doesn't already exist.
// "If it doesn't already exist" because we have the previous migrations
// from Laravel.
return queryInterface.showAllTables().then(function(tableNames) {
if (tableNames.accounts === undefined) {
queryInterface.createTable('accounts', {
// Field definitions here
id: {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
name: Sequelize.STRING,
url_name: Sequelize.STRING,
createdAt: {
type: Sequelize.DATE,
allowNull: false
},
updatedAt: {
type: Sequelize.DATE,
allowNull: false
},
deletedAt: Sequelize.DATE
});
}
});
// See the create-user migration for an explanation of why I
// commented out the above code.
},
down: function (queryInterface, Sequelize) {
return queryInterface.dropTable('accounts');
}
};
'use strict';
module.exports = {
up: function (queryInterface, Sequelize) {
return queryInterface.showAllTables().then(function(tableNames) {
if (tableNames.users === undefined) {
queryInterface.createTable('users', {
id: {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
accountId: {
type: Sequelize.INTEGER,
references: {
model: 'accounts',
key: 'id'
},
allowNull: false
},
email: {
type: Sequelize.STRING,
allowNull: false
},
[...]
});
}
});
},
down: function (queryInterface, Sequelize) {
return queryInterface.dropTable('users');
}
};
然后我启动psql以查看引用是否正确：
databaseName=# \d accounts：
Referenced by:
TABLE "users" CONSTRAINT "users_accountId_fkey" FOREIGN KEY ("accountId") REFERENCES accounts(id)
databaseName=# \d users：
Foreign-key constraints:
"users_accountId_fkey" FOREIGN KEY ("accountId") REFERENCES accounts(id)
到目前为止一切顺利，对吧？
让我们看看这个程序的模型部分！
'use strict';
// account-model.js - A sequelize model
//
// See http://docs.sequelizejs.com/en/latest/docs/models-definition/
// for more of what you can do here.
const Sequelize = require('sequelize');
module.exports = function(app) {
// We assume we're being called from app.configure();
// If we're not, though, we need to be passed the app instance.
// Fair warning: I added this bit myself, so it's suspect.
if (app === undefined)
app = this;
const sequelize = app.get('sequelize');
// The rest of this is taken pretty much verbatim from the examples
const account = sequelize.define('account', {
id: {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
name: Sequelize.STRING,
url_name: Sequelize.STRING,
}, {
paranoid: true,
timestamps: true,
classMethods: {
associate() {
const models = app.get('models');
this.hasMany(models['user'], {});
}
}
});
return account;
};
'use strict';
// user-model.js - A sequelize model
//
// See http://docs.sequelizejs.com/en/latest/docs/models-definition/
// for more of what you can do here.
const Sequelize = require('sequelize');
module.exports = function(app) {
// We assume we're being called from app.configure();
// If we're not, though, we need to be passed the app instance
if (app === undefined)
app = this;
const sequelize = app.get('sequelize');
const user = sequelize.define('user', {
id: {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
accountId: {
type: Sequelize.INTEGER,
references: {
model: 'accounts', // Table name...is that right? Made the migration work...
key: 'id'
}
},
email: Sequelize.STRING,
[... curtailed for brevity ...]
}, {
// Are these necessary here, or just when defining the model to make a
// psuedo-migration?
paranoid: true, // soft deletes
timestamps: true,
classMethods: {
associate() {
const models = app.get('models');
// This outputs like I'd expect:
// Just to be sure...From the user model, models["account"]: account
console.log('Just to be sure...From the user model, models["account"]:', models['account']);
this.belongsTo(models['account'], {});
}
}
});
return user;
};
// I blatantly ripped this from both the following:
// https://github.com/feathersjs/generator-feathers/issues/94#issuecomment-204165134
// https://github.com/feathersjs/feathers-demos/blob/master/examples/migrations/sequelize/src/models/index.js
const Sequelize = require('sequelize');
const _ = require('lodash');
// Import the models
const account = require('./account');
const user = require('./user');
module.exports = function () {
const app = this;
// Note: 'postgres' is found in config/default.json as the db url
const sequelize = new Sequelize(app.get('postgres'), {
dialect: app.get('db_dialect'),
logging: console.log
});
app.set('sequelize', sequelize);
// Configure the models
app.configure(account);
app.configure(user);
app.set('models', sequelize.models);
// Set associations
Object.keys(sequelize.models).forEach(modelName => {
if ('associate' in sequelize.models[modelName]) {
sequelize.models[modelName].associate();
}
});
sequelize.sync();
// Extra credit: Check to make sure the two instances of sequelize.models are the same...
// Outputs: sequelize.models after sync === app.get("models")
// I've also run this comparison on sequelize and app.get('sequelize'); _.eq() said they also were identical
if (_.eq(sequelize.models, app.get('models')))
console.log('sequelize.models after sync === app.get("models")');
else
console.log('sequelize.models after sync !== app.get("models")');
};
为了简洁起见，我为此付出了很多努力，我在app加载了模型，如下所示：
const models = require('./models')
app.use(compress())
// Lots of other statements
.configure(models);
我一直在尝试创建一个命令行实用程序来更改密码，修改用户权限和其他实用程序任务，所以我已经占用了Vorpal（再次，只有2个链接，所以你就可以了如果你不熟悉，你必须自己查阅 - 抱歉）。以下是我的Vorpal计划的相关摘要：
const vorpal = require('vorpal')();
const _ = require('lodash');
// Initialize app
// This seems a bit overkill since we don't need the server bit for this, but...
const app = require('./src/app');
const models = app.get('models');
// Get the models for easy access...
const User = models['user'];
const Account = models['account'];
// Run by issuing the command: node cli test
// Outputs to terminal
vorpal.command('test', 'A playground for testing the Vorpal environment.')
.action(function(args, callback) {
// User.belongsTo(Account); // <-- uncomment this and it works
User.findOne({ include: [{ model: Account }]}).then((user) => {
console.log("user.account.name:", user.account.name);
});
});
vorpal.show().parse(process.argv);
很抱歉，我们花了很长时间才到达这里，但我不知道这部分是相关的部分，所以我不得不把它全部呕吐。
正在运行node cli test会给我一个错误
Just to be sure...From the user model, models["account"]: account
sequelize.models after sync === app.get("models")
connect:
Unhandled rejection Error: account is not associated to user!
at validateIncludedElement (/vagrant/node_modules/sequelize/lib/model.js:550:11)
at /vagrant/node_modules/sequelize/lib/model.js:432:29
at Array.map (native)
at validateIncludedElements (/vagrant/node_modules/sequelize/lib/model.js:428:37)
at .<anonymous> (/vagrant/node_modules/sequelize/lib/model.js:1364:32)
at tryCatcher (/vagrant/node_modules/bluebird/js/release/util.js:16:23)
at Promise._settlePromiseFromHandler (/vagrant/node_modules/bluebird/js/release/promise.js:504:31)
at Promise._settlePromise (/vagrant/node_modules/bluebird/js/release/promise.js:561:18)
at Promise._settlePromise0 (/vagrant/node_modules/bluebird/js/release/promise.js:606:10)
at Promise._settlePromises (/vagrant/node_modules/bluebird/js/release/promise.js:685:18)
at Async._drainQueue (/vagrant/node_modules/bluebird/js/release/async.js:138:16)
at Async._drainQueues (/vagrant/node_modules/bluebird/js/release/async.js:148:10)
at Immediate.Async.drainQueues (/vagrant/node_modules/bluebird/js/release/async.js:17:14)
at runCallback (timers.js:574:20)
at tryOnImmediate (timers.js:554:5)
at processImmediate [as _immediateCallback] (timers.js:533:5)
哎！
但是，如果我取消注释User.findOne()正上方的线条，它就像魅力一样。
为什么在查询关系之前必须明确设置关系 ？为什么在用户模型的associate（）方法中建立的关系（可能）没有坚持？据我所知，它被称为 - 并且在适当的模型上。它是否以某种方式被覆盖？出于某种奇怪的原因，app在用户模型中与cli.js进行关联时是不一样的？
我真的很困惑。所有人都可以提供任何帮助，非常感谢。
答案 0 :(得分：2)
我不知道为什么会这样，但我确实通过进行以下更改来实现它。
我在导出函数末尾附近注释掉了下面的块：
Object.keys(sequelize.models).forEach(modelName => {
if ('associate' in sequelize.models[modelName]) {
sequelize.models[modelName].associate();
}
});
然后我将其移至src/relate-models.js：
/**
* This is workaround for relating models.
* I don't know why it works, but it does.
*
* @param app The initialized app
*/
module.exports = function(app) {
const sequelize = app.get('sequelize');
// Copied this from src/models/index.js
Object.keys(sequelize.models).forEach(modelName => {
if ('associate' in sequelize.models[modelName]) {
sequelize.models[modelName].associate();
}
});
}
在src/app.js我调用了这个函数并且... presto change-o，它起作用了。
const models = require('./models')
app.use(compress())
// Lots of other statements
.configure(models);
require('./relate-models')(app);
结束。如果有人解释为什么以后做同样的事情会有效，请告诉我，但是现在......它有效。