更新操作符是用于更新MongoDB文档中字段值的特殊操作符：

$currentDate：将字段的值设置为当前日期或当前时间戳，可以使用该操作符来更新现有字段或创建新字段。
$inc：将字段的值增加指定的数值。如果字段不存在，则创建该字段并设置初始值为指定的数值。
$min：如果字段的值大于指定的值，则将字段的值更新为指定的值。
$max：如果字段的值小于指定的值，则将字段的值更新为指定的值。
$mul：将字段的值乘以指定的数值。如果字段不存在，则创建该字段并设置初始值为0。
$rename：重命名字段。
$set：设置字段的值。如果字段不存在，则创建该字段并设置初始值为指定的值。
$setOnInsert：仅在插入文档时设置字段的值。如果文档已存在，则不会对字段进行更新。
$unset：删除字段。

1. 测试数据构造

db.student.insertMany([{name: "Alice",age: 25,email: "Alice@example.com",details: { height: 175, weight: 150 },hobbies: ["reading", "writing", "music"],course: [{ subject: "math", score: 90 },{ subject: "english", score: 80 }]},{name: "John",age: 30,email: "John@qq.com",details: { height: 178, weight: 180 },hobbies: ["reading", "gaming", "traveling"],course: [{ subject: "math", score: 70 },{ subject: "english", score: 80 }]},{name: "Jane",age: 25,email: "Jane@qq.com",details: { height: 160, weight: 100 },hobbies: ["sports", "music", "cooking"],course: [{ subject: "math", score: 70 },{ subject: "english", score: 60 }]}
])

@AllArgsConstructor
@NoArgsConstructor
@Data
@Document(collection = "student")
public class Student {@Idprivate String Id;private String name;private Integer age;private String email;private Details details;private List<String> hobbies;private List<Course> course;@Datapublic static class Details {private Integer height;private Integer weight;}@Datapublic static class Course {private String subject;private Integer score;}
}

2. $set

$set 用于更新文档中的字段值或添加新字段，如果指定多个字段值对，$set 将更新或创建每个字段。

db.collection.update(<query>,{ $set: { <field1>: <value1>, ... } }
)

2.1 更新字段的值

查询 student 集合中 name=Alice 的第一个文档，将 email 字段的值更新为 Alice@163.com ，age 字段的值更新为 20：

db.user.updateOne({ name: "Alice" },{ $set: { age: 20, email: "Alice@163.com" } }
)db.student.findOne( { name: "Alice" } )

@Test
public void updateUser(){// 创建查询条件Criteria criteria = Criteria.where("name").is("Alice");// 创建查询对象Query query = new Query(criteria);// 创建更新对象Update update = new Update();update.set("age",20);update.set("email","Alice@163.com");// 执行更新操作UpdateResult updateResult = mongoTemplate.updateFirst(query, update, Student.class);// 执行查询操作Student student = mongoTemplate.findOne(query, Student.class);System.out.println(student);
}

查询结果：

{"_id": ObjectId("6695aa76cdfcb4377f062e6e"),"name": "Alice","age": Int32("20"),"email": "Alice@163.com","details": {"height": 175,"weight": 150},"hobbies": ["reading","writing","music"],"course": [{"subject": "math","score": 90},{"subject": "english","score": 80}]
}

2.2 新增字段的值

查询 student 集合中 name=Alice 的第一个文档，新增字段 gender 并将值置为 female：

db.student.updateOne({ name: "Alice" },{ $set: { gender: "female" } }
)db.student.findOne( { name: "Alice" } )

@AllArgsConstructor
@NoArgsConstructor
@Data
@Document(collection = "student")
public class Student {@Idprivate String Id;private String name;private Integer age;private String email;private Details details;private List<String> hobbies;private List<Course> course;private String gender;@Datapublic static class Details {private Integer height;private Integer weight;}@Datapublic static class Course {private String subject;private Integer score;}
}

@Test
public void updateUser(){// 创建查询条件Criteria criteria = Criteria.where("name").is("Alice");// 创建查询对象Query query = new Query(criteria);// 创建更新对象Update update = new Update();update.set("gender","female");// 执行更新操作UpdateResult updateResult = mongoTemplate.updateFirst(query, update, Student.class);// 执行查询操作Student student = mongoTemplate.findOne(query, Student.class);System.out.println(student);
}

查询结果：

{"_id": ObjectId("6695aa76cdfcb4377f062e6e"),"name": "Alice","age": Int32("20"),"email": "Alice@163.com","details": {"height": 175,"weight": 150},"hobbies": ["reading","writing","music"],"course": [{"subject": "math","score": 90},{"subject": "english","score": 80}],"gender": "female"
}

2.3 更新嵌入式文档字段的值

查询 student 集合中 name=Alice 的第一个文档，将嵌入式 details 文档中的 weight 字段设置为120：

db.student.updateOne({ name: "Alice" },{ $set: { "details.weight": 120} }
)db.student.findOne( { name: "Alice" } )

 @Testpublic void updateUser(){// 创建查询条件Criteria criteria = Criteria.where("name").is("Alice");// 创建查询对象Query query = new Query(criteria);// 创建更新对象Update update = new Update();update.set("details.weight",120);// 执行更新操作UpdateResult updateResult = mongoTemplate.updateFirst(query, update, Student.class);// 执行查询操作Student student = mongoTemplate.findOne(query, Student.class);System.out.println(student);
}

查询结果：

{"_id": ObjectId("6695aa76cdfcb4377f062e6e"),"name": "Alice","age": Int32("20"),"email": "Alice@163.com","details": {"height": 175,"weight": 120},"hobbies": ["reading","writing","music"],"course": [{"subject": "math","score": 90},{"subject": "english","score": 80}],"gender": "female"
}

2.4 更新数组字段的元素值

查询 student 集合中 name=Alice 的第一个文档，将hobbies数组中的第一个元素更新为cooking：

db.student.updateOne({ name: "Alice" },{ $set: { "hobbies.0": "cooking"} }
)db.student.findOne( { name: "Alice" } )

 @Testpublic void updateUser(){// 创建查询条件Criteria criteria = Criteria.where("name").is("Alice");// 创建查询对象Query query = new Query(criteria);// 创建更新对象Update update = new Update();update.set("hobbies.0","cooking");// 执行更新操作UpdateResult updateResult = mongoTemplate.updateFirst(query, update, Student.class);// 执行查询操作Student student = mongoTemplate.findOne(query, Student.class);System.out.println(student);
}

查询结果：

{"_id": ObjectId("6695aa76cdfcb4377f062e6e"),"name": "Alice","age": Int32("20"),"email": "Alice@163.com","details": {"height": 175,"weight": 120},"hobbies": ["cooking","writing","music"],"course": [{"subject": "math","score": 90},{"subject": "english","score": 80}],"gender": "female"
}

3. $unset

$unset 操作符用于删除指定字段：

db.collection.update(<query>,{ $unset: { <field1>: "", <field2>: "", ... } },{ <options> }
)

要删除age和email字段，可以使用以下命令：

db.user.insertOne({ name: "Alice", age: 25, email: "alice@example.com" 
});

db.user.update({"name": "Alice"},{ $unset: { age: "", email: ""} }
)db.user.findOne( { name: "Alice" } )

@AllArgsConstructor
@NoArgsConstructor
@Data
@Document(collection = "user")
public class User {@Idprivate String id;private String name;private Integer age;private String email;
}

 @Testpublic void updateUser(){// 创建查询条件Criteria criteria = Criteria.where("name").is("Alice");// 创建查询对象Query query = new Query(criteria);// 创建更新对象Update update = new Update();update.unset("age");update.unset("email");// 执行更新操作UpdateResult updateResult = mongoTemplate.updateFirst(query, update, User.class);// 执行查询操作User user = mongoTemplate.findOne(query, User.class);System.out.println(user);
}

4. $currentDate

$currentDate 将字段的值设置为当前日期或当前时间戳，可以使用该操作符来更新现有字段或创建新字段。

db.collection.updateOne({ <query> },{ $currentDate: { <field1>: true, <field2>: { $type: "date" } } }
)

$currentDate 操作符可以接受不同的值来设置字段的值：

• true：将字段的值设置为当前日期和时间。

• { $type: “date” }：将字段的值设置为当前日期，忽略时间部分。

db.users.updateOne({ _id: 1 },{ $currentDate: { lastModified: true, registrationDate: { $type: "date" } } }
)

users 集合中 _id 为 1 的文档的 lastModified 字段将被设置为当前日期和时间，而 registrationDate 字段将被设置为当前日期，忽略时间部分。

5. $inc

$inc 将字段的值增加指定的数值。如果字段不存在，则创建该字段并设置初始值为指定的数值。

db.collection.updateOne({ <query> },{ $inc: { <field1>: <amount1>, <field2>: <amount2>, ... } }
)

5.1 更新字段的值

查询 student 集合中 name=Alice 的第一个文档，将 age+5：

db.student.updateOne({ name: "Alice" },{ $inc: { age: 5 } }
)db.student.findOne( { name: "Alice" } )

@Test
public void updateUser(){// 创建查询条件Criteria criteria = Criteria.where("name").is("Alice");// 创建查询对象Query query = new Query(criteria);// 创建更新对象Update update = new Update();update.inc("age",5);// 执行更新操作UpdateResult updateResult = mongoTemplate.updateFirst(query, update, Student.class);// 执行查询操作Student student = mongoTemplate.findOne(query, Student.class);System.out.println(student);
}

查询结果：

{"_id": ObjectId("6695aa76cdfcb4377f062e6e"),"name": "Alice","age": 25,"email": "Alice@163.com","details": {"height": 175,"weight": 120},"hobbies": ["cooking","writing","music"],"course": [{"subject": "math","score": 90},{"subject": "english","score": 80}],"gender": "female"
}

5.2 新增字段的值

查询 student 集合中 name=Alice 的第一个文档，如果 amount 字段不存在将会新增该字段：

db.student.updateOne({ name: "Alice" },{ $inc: { amount : 5 } }
)db.student.findOne( { name: "Alice" } )

@Data
@Document(collection = "student")
public class Student {@Idprivate String Id;private String name;private Integer age;private String email;private Details details;private List<String> hobbies;private List<Course> course;private String gender;// 新增的字段private Integer amount;@Datapublic static class Details {private Integer height;private Integer weight;}@Datapublic static class Course {private String subject;private Integer score;}
}

@Test
public void updateUser(){// 创建查询条件Criteria criteria = Criteria.where("name").is("Alice");// 创建查询对象Query query = new Query(criteria);// 创建更新对象Update update = new Update();update.inc("amount",5);// 执行更新操作UpdateResult updateResult = mongoTemplate.updateFirst(query, update, Student.class);// 执行查询操作Student student = mongoTemplate.findOne(query, Student.class);System.out.println(student);
}

查询的结果：

{"_id": ObjectId("66928a18cdfcb4377f062e42"),"name": "Alice","age": 30,"email": "Alice@example.com","details": {"height": 175,"weight": 120},"hobbies": ["cooking","writing","music"],"course": [{"subject": "math","score": 90},{"subject": "english","score": 80}],"gender": "female","amount": 5
}

5.3 递增多个字段值

查询 student 集合中 name=Alice 的第一个文档，将age+5，嵌入式文档details的weight+5：

db.student.updateOne({ name: "Alice" },{ $inc: { age: 2, "details.weight": 5} }
)

@Test
public void updateUser(){// 创建查询条件Criteria criteria = Criteria.where("name").is("Alice");// 创建查询对象Query query = new Query(criteria);// 创建更新对象Update update = new Update();update.inc("age",-2);update.inc("details.weight",-5);// 执行更新操作UpdateResult updateResult = mongoTemplate.updateFirst(query, update, Student.class);// 执行查询操作Student student = mongoTemplate.findOne(query, Student.class);System.out.println(student);
}

查询的结果：

{"_id": ObjectId("6695aa76cdfcb4377f062e6e"),"name": "Alice","age": 23,"email": "Alice@163.com","details": {"height": 175,"weight": 115},"hobbies": ["cooking","writing","music"],"course": [{"subject": "math","score": 90},{"subject": "english","score": 80}],"gender": "female","amount": 5
}

6. $rename

$rename更新字段的名称：

db.collection.update({ <query> },{ $rename: { <field1>: <newName1>, <field2>: <newName2>, ... } }
)

查询 student 集合中 name=Alice 的第一个文档，将name更名为newName，age更名为newAge:

db.student.updateOne({ name: "Alice" },{ $rename: {age: "newAge",name: "newName"} }
)

查询 student 集合中 newName=Alice 的第一个文档：

db.student.findOne({newName:"Alice"})

{"_id": ObjectId("6695dfb6197700004d003dda"),"email": "Alice@example.com","details": {"height": 175,"weight": 150},"hobbies": ["reading","writing","music"],"course": [{"subject": "math","score": 90},{"subject": "english","score": 80}],"newAge": 25,"newName": "Alice"
}

查询 student 集合中name=Alice 的第一个文档：null