极客笔记MongoDB $rename 运算符
MongoDB 中的 $rename 运算符是什么
MongoDB 提供了各种字段更新运算符来更新字段的值。$rename 运算符就是其中之一。$rename 运算符用于更改字段的名称。字段的新名称必须与字段的旧名称不同。
重要提示:
- 在对新名称执行
$set操作之前，$rename运算符会对旧名称和新名称都执行 $unset 操作。 - 它还可以与数组或嵌套文档一起使用。
- 根据需求，您可以在 findAndModify()、like()、update() 等函数中使用此运算符。
- 如果文档中没有给定的字段需要重命名，则 $rename 运算符不会做任何操作。
$rename 运算符的语法
{ $rename : { : , : , ... } }
示例
在下面的示例中，我们正在处理：
Database: JavaTpoint
Collection: employees
Document: Six documents that contain the details of the employees
>db.employees.find().pretty()
{
"_id" : 1,
"employee_name" : "Tin",
"father_name" : "Thor",
"department" : "Tester",
"address" : "London",
"joinning" : 2020,
"phone_no" : 9856321478,
"gender" : "Male",
"age" : 20,
"salary" : 10000
}
{
"_id" : 2,
"employee_name" : "John",
"father_name" : "Mick",
"department" : "Tester",
"address" : "NewYork",
"joining" : 2015,
"phone_no" : 7896541478,
"gender" : "Male",
"age" : 23,
"salary" : 20000,
"report_lastDate" : ISODate("2021-08-05T00:00:00Z")
}
{
"_id" : 3,
"employee_name" : "Ammy john",
"father_name" : "John",
"department" : "Software developer",
"address" : "London",
"joining" : 2019,
"phone_no" : 7985631478,
"gender" : "Female",
"age" : 26,
"salary" : 15000
}
{
"_id" : 4,
"employee_name" : "Reeza",
"father_name" : "Reeza Hendricks",
"department" : "Tester",
"address" : "USA",
"joining" : 2020,
"phone_no" : 7412563278,
"gender" : "Male",
"age" : 22,
"salary" : 20000
}
{
"_id" : 5,
"employee_name" : "John Lewis",
"father_name" : "Lewis",
"department" : "Software developer",
"address" : "London",
"joining" : 2015,
"phone_no" : 9632587418,
"gender" : "Male",
"age" : 25,
"salary" : 25000,
}
{
"_id" : 6,
"employee_name" : "Temba",
"father_name" : "George",
"department" : "Tester",
"address" : "NewYork",
"joining" : 2018,
"phone_no" : 8965247418,
"gender" : "Male",
"age" : 24,
"salary" : {
"first_month" : 15000,
"second_month" : 18000,
"bonus" : 2000
}
}
示例1：重命名单个字段
在这个示例中，我们将测试部门员工文档中的”joining”字段名称更改为”joinYear”。
db.employees.update( {"department": "Tester"},
{$rename: {"joining": "joinYear"}})
输出：
{
"_id" : 1,
"employee_name" : "Tin",
"father_name" : "Thor",
"department" : "Tester",
"address" : "London",
"joinYear" : 2020,
"phone_no" : 9856321478,
"gender" : "Male",
"age" : 20,
"salary" : 10000
}
{
"_id" : 2,
"employee_name" : "John",
"father_name" : "Mick",
"department" : "Tester",
"address" : "NewYork",
"joinYear" : 2015,
"phone_no" : 7896541478,
"gender" : "Male",
"age" : 23,
"salary" : 20000,
"report_lastDate" : ISODate("2021-08-05T00:00:00Z")
}
{
"_id" : 4,
"employee_name" : "Reeza",
"father_name" : "Reeza Hendricks",
"department" : "Tester",
"address" : "USA",
"joinYear" : 2020,
"phone_no" : 7412563278,
"gender" : "Male",
"age" : 22,
"salary" : 20000
}
{
"_id" : 6,
"employee_name" : "Temba",
"father_name" : "George",
"department" : "Tester",
"address" : "NewYork",
"joinYear" : 2018,
"phone_no" : 8965247418,
"gender" : "Male",
"age" : 24,
"salary" : {
"first_month" : 15000,
"second_month" : 18000,
"bonus" : 2000
}
}
示例2：将文档中多个字段的名称进行更名
在这个示例中，我们将”phone_no”字段的名称更名为”contact_no”，并应用于employees集合中的所有文档。
db.employees.updateMany( {}, {$rename: {"phone_no": "contact_no"}})
输出：
{
"_id" : 1,
"employee_name" : "Tin",
"father_name" : "Thor",
"department" : "Tester",
"address" : "London",
"joining" : 2020,
"contact_no" : 9856321478,
"gender" : "Male",
"age" : 20,
"salary" : 10000
}
{
"_id" : 2,
"employee_name" : "John",
"father_name" : "Mick",
"department" : "Tester",
"address" : "NewYork",
"joining" : 2015,
"contact_no" : 7896541478,
"gender" : "Male",
"age" : 23,
"salary" : 20000,
"report_lastDate" : ISODate("2021-08-05T00:00:00Z")
}
{
"_id" : 3,
"employee_name" : "Ammy john",
"father_name" : "John",
"department" : "Software developer",
"address" : "London",
"joining" : 2019,
"contact_no" : 7985631478,
"gender" : "Female",
"age" : 26,
"salary" : 15000
}
{
"_id" : 4,
"employee_name" : "Reeza",
"father_name" : "Reeza Hendricks",
"department" : "Tester",
"address" : "USA",
"joining" : 2020,
"contact_no" : 7412563278,
"gender" : "Male",
"age" : 22,
"salary" : 20000
}
{
"_id" : 5,
"employee_name" : "John Lewis",
"father_name" : "Lewis",
"department" : "Software developer",
"address" : "London",
"joining" : 2015,
"contact_no" : 9632587418,
"gender" : "Male",
"age" : 25,
"salary" : 25000,
}
{
"_id" : 6,
"employee_name" : "Temba",
"father_name" : "George",
"department" : "Tester",
"address" : "NewYork",
"joining" : 2018,
"contact_no" : 8965247418,
"gender" : "Male",
"age" : 24,
"salary" : {
"first_month" : 15000,
"second_month" : 18000,
"bonus" : 2000
}
}
示例3：重命名嵌套文档中的字段
在此示例中，我们将名为“salary.first_month”的字段名称在员工文档中更改为“salary.month”，该文档的employee_name是Temba。
db.employee.update({"employee_name": "Temba"},
{$rename: {"salary.first_month": "salary.month"}})
输出：
{
"_id" : 6,
"employee_name" : "Temba",
"father_name" : "George",
"department" : "Tester",
"address" : "NewYork",
"joining" : 2018,
"phone_no" : 8965247418,
"gender" : "Male",
"age" : 24,
"salary" : {
"month" : 15000,
"second_month" : 18000,
"bonus" : 2000
}
}