Mongoose - 'pre'中间件中的返回错误

Question

如果验证失败,如何发送自定义错误消息schema.pre('save')？例如,如果我有聊天功能,您创建新会话,我想检查与给定参与者的会话是否已经存在,所以我可以这样做:

ConversationSchema.pre('save', function(next, done) {
    var that = this;
    this.constructor.findOne({participants: this.participants}).then(function(conversation) {
        if (conversation) {
            // Send error back with the conversation object
        } else {
            next();
        }
    });
});

Answer 1

Error在调用时传递对象next以报告错误:

ConversationSchema.pre('save', function(next, done) {
    var that = this;
    this.constructor.findOne({participants: this.participants}).then(function(conversation) {
        if (conversation) {
            var err = new Error('Conversation exists');
            // Add conversation as a custom property
            err.conversation = conversation;
            next(err);
        } else {
            next();
        }
    });
});

文档在这里.