问题描述
假设我有以下数据库实体:
let's say I have the following database entity:
@Document(collection = "users") public class User { @Id private String id; private String firstname; private String lastname; private String email; }
如何强制字段电子邮件是唯一的?这意味着当应用程序尝试保存实体时,MongoDB 应该检查是否已经存在使用此电子邮件地址的用户记录.
How can I enforce the field email to be unique? That means MongoDB should check if a user record with this email address already exists when the application tries to save the entity.
问候,史蒂芬
推荐答案
MongoDB需要创建一个字段并建立索引,才能知道该字段是否唯一.
Mongodb needs to create and index a field in order to know whether the field is unique or not.
@Indexed(unique=true) private String email;