Update操作只作用于集合中存在的文档。MongoDB提供了如下方法来更新集合中的文档:
你可以通过指定criteria或者filter来指定你想更新的文档:
update函数执行数据更新操作,该函数接受3个主要参数:criteria,action,options:
为了更好的演示,插入数据:
db.users.insertMany(
[
{
_id: 1,
name: "sue",
age: 19,
type: 1,
status: "P",
favorites: { artist: "Picasso", food: "pizza" },
finished: [ 17, 3 ],
badges: [ "blue", "black" ],
points: [
{ points: 85, bonus: 20 },
{ points: 85, bonus: 10 }
]
},
{
_id: 2,
name: "bob",
age: 42,
type: 1,
status: "A",
favorites: { artist: "Miro", food: "meringue" },
finished: [ 11, 25 ],
badges: [ "green" ],
points: [
{ points: 85, bonus: 20 },
{ points: 64, bonus: 12 }
]
},
{
_id: 3,
name: "ahn",
age: 22,
type: 2,
status: "A",
favorites: { artist: "Cassatt", food: "cake" },
finished: [ 6 ],
badges: [ "blue", "Picasso" ],
points: [
{ points: 81, bonus: 8 },
{ points: 55, bonus: 20 }
]
},
{
_id: 4,
name: "xi",
age: 34,
type: 2,
status: "D",
favorites: { artist: "Chagall", food: "chocolate" },
finished: [ 5, 11 ],
badges: [ "Picasso", "black" ],
points: [
{ points: 53, bonus: 15 },
{ points: 51, bonus: 15 }
]
},
{
_id: 5,
name: "xyz",
age: 23,
type: 2,
status: "D",
favorites: { artist: "Noguchi", food: "nougat" },
finished: [ 14, 6 ],
badges: [ "orange" ],
points: [
{ points: 71, bonus: 20 }
]
},
{
_id: 6,
name: "abc",
age: 43,
type: 1,
status: "A",
favorites: { food: "pizza", artist: "Picasso" },
finished: [ 18, 12 ],
badges: [ "black", "blue" ],
points: [
{ points: 78, bonus: 8 },
{ points: 57, bonus: 7 }
]
}
]
)
下面的例子使用update()函数执行更新数据操作,不包含操作符:
> db.users.find({"name":"xyz"});
{ "_id" : 5, "name" : "xyz", "age" : 23, "type" : 2, "status" : "D", "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 14, 6 ], "badges" : [ "orange" ], "points" : [ { "points" : 71, "bonus" : 20 } ] }
>
修改之后:
> db.users.update({"name":"xyz"}, {name : "xyz", age:25, school : "xidian", type:1, favorites: {artist : "Noguchi", food : "nougat"}, finished : [4, 5] }, {upsert:true});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
>
>
>
> db.users.find({"name":"xyz"});
{ "_id" : 5, "name" : "xyz", "age" : 25, "school" : "xidian", "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }
该例覆写了集合中的文档,并保存更新后的值。
备注
任何忽略的字段都被移除(文档被覆盖)
upsert可以指定如果数据存在就更新,不存在就创建数据。
> db.users.find({"name":"yoona"});
>
> db.users.update({"name":"yoona"}, {name : "yoona", age:25, "school" : "xidian", type:1, favorites: {artist : "Noguchi", food : "nougat"}, finished : [4, 5] }, {upsert:false});
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
更新操作之前我们没有查询到yoona的任何信息,然后我们对其进行更新操作,并且upsert设置为false,表示如果更新的数据不存在,不走任何操作。更新之后,我们再次查询一下:
> db.users.find({"name":"yoona"});
>
再次查询还是没有找到相应数据。我们设置upsert为true,表示如果数据存在则更新,如果不存在则创建该数据:
> db.users.update({"name":"yoona"}, {name : "yoona", age:25, "school" : "xidian", type:1, favorites: {artist : "Noguchi", food : "nougat"}, finished : [4, 5] }, {upsert:true});
WriteResult({
"nMatched" : 0,
"nUpserted" : 1,
"nModified" : 0,
"_id" : ObjectId("57c3ad26d2cc0133a95bc583")
})
>
> db.users.find({"name":"yoona"});
{ "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "name" : "yoona", "age" : 25, "school" : "xidian", "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }
操作符$inc可以为指定的键执行(原子)更新操作,如果字段存在,就将该值增加给定的增量,如果该字段不存在,就创建该字段。
> db.users.update({"name":"yoona"}, {$inc:{age:2}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
>
>
> db.users.find({name:"yoona"});
{ "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "name" : "yoona", "age" : 27, "school" : "xidian", "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }
上面例子中将yoona用户的年龄增加两岁。
可以使用$set操作符将某个字段设置为指定值。
> db.users.find({name:"yoona"});
{ "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "name" : "yoona", "age" : 27, "school" : "xidian", "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }
>
> db.users.update({"name":"yoona"}, {$set:{school:"Massachusetts Institute of Technology"}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
>
> db.users.find({name:"yoona"});
{ "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "name" : "yoona", "age" : 27, "school" : "Massachusetts Institute of Technology", "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }
>
上面例子将yoona用户的学校改为麻省理工学院。
> db.users.find({name:"yoona"});
{ "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "name" : "yoona", "age" : 27, "school" : "Massachusetts Institute of Technology", "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }
>
> db.users.update({"name":"yoona"}, {$unset:{school:"Massachusetts Institute of Technology"}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
>
> db.users.find({name:"yoona"});
{ "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "name" : "yoona", "age" : 27, "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }
上面例子将yoona用户的学校删除。
格式:
{$rename: { : , : , ... } }
新字段名称必须不同与已经存在的字段名称
> db.users.find({name:"yoona"});
{ "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "name" : "yoona", "age" : 27, "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }
>
> db.users.update({"name":"yoona"}, {$rename: {name:"userName", age:"userAge"}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
>
查询:
> db.users.find({name:"yoona"});
> db.users.find({userName:"yoona"});
{ "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ], "userName" : "yoona", "userAge" : 27 }
>
上面例子中使用$rename将name改为userName,将age改为userAge。
如果给定值(value1)小于字段的当前值,则更新字段值为给定值。$min运算符可以可以比较不同类型的数字。
格式:
{ $min: { : , ... } }
为了演示,添加如下数据:
> db.score.save({_id:1, highScore:90, lowScore: 50});
WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : 1 })
>
>
> db.score.find();
{ "_id" : 1, "highScore" : 90, "lowScore" : 50 }
给定值与字段当前值进行比较,给定值10小于字段的当前值50,所以更新字段当前值为给定值10:
> db.score.update({_id:1}, {$min : {lowScore : 10}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
>
> db.score.find();
{ "_id" : 1, "highScore" : 90, "lowScore" : 10 }
给定值40大于字段当前值10,不做任何变化:
> db.score.update({_id:1}, {$min : {lowScore : 40}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
>
> db.score.find();
{ "_id" : 1, "highScore" : 90, "lowScore" : 10 }
>
如果更新操作设置upsert:true,执行insert操作时,$setOnInsert会给给定字段赋值给定值。如果更新操作不会导致插入数据,$setOnInsert不会有任何作用。
格式:
db.collection.update(
,
{ $setOnInsert: { : , ... } },
{ upsert: true }
)
举例:
假设集合products中没有任何文档,进行如下操作:
> db.products.find();
>
> db.products.update({_d:1}, {$set : {item : "apple"}, $setOnInsert : {defaultQty : 100}} , {upsert : true});
WriteResult({
"nMatched" : 0,
"nUpserted" : 1,
"nModified" : 0,
"_id" : ObjectId("57c43a0ebd7a19639b912212")
})
>
> db.products.find();
{ "_id" : ObjectId("57c43a0ebd7a19639b912212"), "_d" : 1, "item" : "apple", "defaultQty" : 100 }
由于集合中没有任何文档,在对其字段item进行更新时,由于item字段不存在,执行insert操作时,触发setOnInsert操作符,给defaultQty字段赋值为100。
$curentDate设置字段值为当前日期,可以设置Date类型或者timestamp类型。
格式:
{ $currentDate: { : , ... } }
为了演示,添加如下数据:
db.student.save({_id:1, name: "yoona", age: 24, college: "计算机学院"});
下面添加一个日期类型的"birthday"字段:
db.student.update({_id:1}, {$currentDate: {birthday: {$type: "date"}}});
最后输出结果:
{
"_id" : 1.0,
"name" : "yoona",
"age" : 24.0,
"college" : "计算机学院",
"birthday" : ISODate("2016-08-30T02:29:24.425Z")
}
通过$push操作符可以在指定字段中添加某个值。如果该字段是个数组,那么该值将被添加到数组中。如果该字段尚不存在,那么该字段的值将被设置为数组。如果该字段存在,但不是数组,那么将会抛出异常。如果给定的值是个数组,那么该数组被看做是一个元素,添加给定字段中(If the value is an array, $push appends the whole array as a single element)。
格式:
{ $push: { : , ... } }
举例:
添加一个分数到成绩数组中:
db.student.update({_id:1}, {$push : {scores: 91}});
输出结果:
{
"_id" : 1.0,
"name" : "yoona",
"age" : 24.0,
"college" : "计算机学院",
"birthday" : ISODate("2016-08-30T02:29:24.425Z"),
"scores" : [
89.0,
91.0
]
}
格式:
{ $push: { : { $each: [ , ... ] } } }
使用$push操作符可以将值添加到指定数组中,扩展指定元素中存储的数据。如果希望在给定的数组中添加多个值,可以使用可选的$each修改操作符。
db.student.update(
{ _id: 1 },
{ $push: { scores: { $each: [ 90, 92, 85 ] } } }
)
输出结果:
{
"_id" : 1.0,
"name" : "yoona",
"age" : 24.0,
"college" : "计算机学院",
"birthday" : ISODate("2016-08-30T02:29:24.425Z"),
"scores" : [
89.0,
91.0,
90.0,
92.0,
85.0
]
}
在使用$each是还可以使用$slice修改操作符,通过这种方式可以限制$push操作符中数组内元素的数量。$slice可以是正数,负数或0。正数将保证数组中的前n个元素会被保留,使用负数将保证数组中的最后n个元素会被保留,而使用0则表示清空数组。注意:操作符$slice必须是$push操作中的第一个修改操作符。
使用0则表示清空数组:
db.student.update(
{ _id: 1 },
{ $push: { scores: { $each: [ 70, 78], $slice: 0 } } }
)
输出结果:
{
"_id" : 1.0,
"name" : "yoona",
"age" : 24.0,
"college" : "计算机学院",
"birthday" : ISODate("2016-08-30T02:29:24.425Z"),
"scores" : []
}
正数将保证数组中的前n个元素会被保留
db.student.update(
{ _id: 1 },
{ $push: { scores: { $each: [ 70, 78, 90], $slice: 2 } } }
)
输出结果:
{
"_id" : 1.0,
"name" : "yoona",
"age" : 24.0,
"college" : "计算机学院",
"birthday" : ISODate("2016-08-30T02:29:24.425Z"),
"scores" : [
70.0,
78.0
]
}
使用负数将保证数组中的最后n个元素会被保留
db.student.update(
{ _id: 1 },
{ $push: { scores: { $each: [ 89, 56 ], $slice: -3 } } }
)
输出结果:
{
"_id" : 1.0,
"name" : "yoona",
"age" : 24.0,
"college" : "计算机学院",
"birthday" : ISODate("2016-08-30T02:29:24.425Z"),
"scores" : [
78.0,
89.0,
56.0
]
}
操作符$each和$slice操作符保证不仅新值会被添加到数组中,还能保证吧数组的大小限制为指定值。
$sort修改操作符必须与$each修改操作符一起使用。你可以传递一个空数组给$each操作符,这样就可以只使$sort操作符起作用,达到不添加元素,只对原数组排序的目的。
在对数组元素进行排序时,1表示升序,-1表示降序。如果数组元素是文档,我们可以根据整个文档或者是文档中某个具体字段来进行排序。在以前版本中(2.6版本之前)$sort只能根据文档中的具体字段进行排序。假设数组元素是文档,如果只是根据文档中某个字段进行排序,需要使用字段和方向来进行排序,例如, { field: 1 } or { field: -1 },不要使用{ "arrayField.field": 1 }这种方式进行排序。
格式:
{
$push: {
: {
$each: [ , , ... ],
$sort:
}
}
}
举例:
(1)对数组元素是文档的数组进行排序
为了演示,插入如下数据:
db.students.save(
{
"_id": 1,
"quizzes": [
{ "id" : 1, "score" : 6 },
{ "id" : 2, "score" : 9 }
]
}
)
下面的更新操作,将会添加文档到quizzes 数组中,并且根据数组中文档的score字段进行升序排序:
db.students.update(
{ _id: 1 },
{
$push: {
quizzes: {
$each: [ { id: 3, score: 8 }, { id: 4, score: 7 }, { id: 5, score: 6 } ],
$sort: { score: 1 }
}
}
}
)
输出结果:
{
"_id" : 1.0,
"quizzes" : [
{
"id" : 1.0,"score" : 6.0
},
{
"id" : 5.0,"score" : 6.0
},
{
"id" : 4.0,"score" : 7.0
},
{
"id" : 3.0,"score" : 8.0
},
{
"id" : 2.0,"score" : 9.0
}
]
}
(2)对数组元素不是文档的数组进行排序
为了演示,插入如下数据:
db.students.save({ "_id" : 2, "scores" : [ 89, 70, 89, 50 ] })
下面更新操作,将添加两个元素到数组中,并且对数组进行降序排序:
db.students.update(
{ _id: 2 },
{ $push: { scores: { $each: [ 40, 60 ], $sort: -1 } } }
)
输出结果:
{
"_id" : 2.0,
"scores" : [
89.0,
89.0,
70.0,
60.0,
50.0,
40.0
]
}
(3)只对数组进行排序
db.students.save({ "_id" : 3, "scores" : [ 89, 70, 100, 20 ] })
下面更新操作,只对数组进行排序,不添加元素:
db.students.update(
{ _id: 3 },
{ $push: { scores: { $each: [ ], $sort: 1 } } }
)
输出结果:
{
"_id" : 3.0,
"scores" : [
20.0,
70.0,
89.0,
100.0
]
}
操作符$addToSet 是另一个可用于向数组中添加数据的命令。不过,只有数据不存在的时候,该操作符才能将数据添加到数组中(The $addToSet operator adds a value to an array unless the value is already present, in which case$addToSet does nothing to that array)。它的 工作方式与$push不同,$addToSet确保在添加元素时不会与数组中元素重复($addToSet only ensures that there are no duplicate items added to the set and does not affect existing duplicate elements),但是$push可以添加重复元素。在使用$addToSet时,可以使用$each操作符指定的额外的参数。
如果添加的给定值是个数组,则会把整个数组看做一个元素添加到给定字段中。
格式:
{ $addToSet: { : , ... } }
举例:
(1)给定值是数组
{ _id: 1, letters: ["a", "b"] }
下面更新操作将会把数组["c", "d"]添加到letters字段中:
db.test.update(
{ _id: 1 },
{ $addToSet: {letters: [ "c", "d" ] } }
)
现在letters字段包含一个["c", "d"]数组元素:
{ _id: 1, letters: [ "a", "b", [ "c", "d" ] ] }
如果不想把数组看做一个整个元素添加到指定字段中,而是把数组中的每个元素添加到指定字段中,则需要$each修改操作符配合$addToSet使用。
(2)给定值不是数组,并且指定字段中不存在
考虑如下文档:
{
"_id" : 2.0,
"scores" : [
89.0
]
}
添加元素100到成绩数组scores中,并且100在scores中不存在:
db.students.update({_id: 2}, { $addToSet: { scores: 100 } });
输出结果:
{
"_id" : 2.0,
"scores" : [
89.0,
100.0
]
}
(3)给定值不是数组,并且指定字段中存在
db.students.update({_id: 3}, { $addToSet: { scores: { $each: [ 100, 20, 50 ] } } });
输出结果:
{
"_id" : 2.0,
"scores" : [
89.0,
100.0,
20.0,
50.0
]
}
我们看到scores数组中只有一个100,这与$push工作方式是不同的。
操作符$pop可以从数组中删除单个元素。该操作符允许删除数组中的第一个元素或者最后一个元素,具体取决于传入的参数。如果传递的参数为-1表示删除数组第一个元素,1表示删除数组最后一个元素。如果删除的指定字段field不是数组,则会报错。
格式:
{ $pop: { : <-1 | 1>, ... } }
举例:
{
"_id" : 2.0,
"scores" : [
89.0,
100.0,
20.0,
50.0
]
}
删除第一个元素(89.0):
db.students.update({_id:2}, {$pop: {scores: -1}});
输出结果:
{
"_id" : 2.0,
"scores" : [
100.0,
20.0,
50.0
]
}
删除最后一个元素(50.0):
db.students.update({_id:2}, {$pop: {scores: 1}});
输出结果:
{
"_id" : 2.0,
"scores" : [
100.0,
20.0
]
}
通过使用$pull操作符可以从数组中删除所有指定的值或者符合给定条件的值。如果数组中有多个元素的值相同,那么该操作符是非常有用的。
格式:
{ $pull: { : , : , ... } }
举例:
(1)删除与给定值相等的所有值
为了演示,添加如下数据:
db.stores.save(
{
_id: 1,
fruits: [ "apples", "pears", "oranges", "grapes", "bananas" ],
vegetables: [ "carrots", "celery", "squash", "carrots" ]
});
db.stores.save(
{
_id: 2,
fruits: [ "plums", "kiwis", "oranges", "bananas", "apples" ],
vegetables: [ "broccoli", "zucchini", "carrots", "onions" ]
});
下面更新操作从fruits中删除"apples" 和 "oranges",从vegetables数组中删除"carrots":
db.stores.update({}, {$pull: {fruits: {$in : ["apples", "oranges"]}, vegetables: "carrots" }}, {multi: true});
输出结果:
/* 1 */
{
"_id" : 1.0,
"fruits" : [
"pears",
"grapes",
"bananas"
],
"vegetables" : [
"celery",
"squash"
]
}
/* 2 */
{
"_id" : 2.0,
"fruits" : [
"plums",
"kiwis",
"bananas"
],
"vegetables" : [
"broccoli",
"zucchini",
"onions"
]
}
(2)删除与给定条件相匹配的所有值 为了演示插入如下数据:
db.profiles.save({ _id: 1, votes: [ 3, 5, 6, 7, 7, 8 ] });
下面更新操作删除数组中大于6的元素:
db.profiles.update({_id:1}, {$pull: {votes: {$gte : 6}} });
输出结果:
{
"_id" : 1.0,
"votes" : [
3.0,
5.0
]
}
(3)删除数组中文档类型的数组元素
为了演示,插入如下数据:
db.survey.save({
_id: 1,
results: [
{ item: "A", score: 5 },
{ item: "B", score: 8, comment: "Strongly agree" }
]
});
db.survey.save({
_id: 2,
results: [
{ item: "C", score: 8, comment: "Strongly agree" },
{ item: "B", score: 4 }
]
});
下面更新操作删除数组元素中包含值为8的score字段和值为"B"的item字段:
db.survey.update({ }, {$pull: {results: { score : 8, item : "B" }} }, {multi: true});
输出结果:
{
"_id" : 1.0,
"results" : [
{
"item" : "A",
"score" : 5.0
}
]
}
{
"_id" : 2.0,
"results" : [
{
"item" : "C",
"score" : 8.0,
"comment" : "Strongly agree"
},
{
"item" : "B",
"score" : 4.0
}
]
}
(3)删除数组中嵌套文档的数组元素
为了演示,插入如下数据:
db.survey2.save({
_id: 1,
results: [
{ item: "A", score: 5, answers: [ { q: 1, a: 4 }, { q: 2, a: 6 } ] },
{ item: "B", score: 8, answers: [ { q: 1, a: 8 }, { q: 2, a: 9 } ] }
]
});
db.survey2.save({
_id: 2,
results: [
{ item: "C", score: 8, answers: [ { q: 1, a: 8 }, { q: 2, a: 7 } ] },
{ item: "B", score: 4, answers: [ { q: 1, a: 0 }, { q: 2, a: 8 } ] }
]
});
我们看到文档中嵌套文档,我们如何根据文档中嵌套的文档条件删除呢?下面更新操作删除results数组元素,其满足ansmers字段至少包含一个q值为2以及a大于等于8:
db.survey2.update(
{ },
{ $pull: { results: { answers: { $elemMatch: { q: 2, a: { $gte: 8 } } } } } },
{ multi: true }
)
输出结果:
{
"_id" : 1.0,
"results" : [
{
"item" : "A",
"score" : 5.0,
"answers" : [
{
"q" : 1.0,
"a" : 4.0
},
{
"q" : 2.0,
"a" : 6.0
}
]
}
]
}
{
"_id" : 2.0,
"results" : [
{
"item" : "C",
"score" : 8.0,
"answers" : [
{
"q" : 1.0,
"a" : 8.0
},
{
"q" : 2.0,
"a" : 7.0
}
]
}
]
}
我们还可以从数组中删除多个含有不同值的元素。该操作符将接收一个希望移除元素的数组。不同于$pull,$pull从数组中删除匹配查询条件的数组元素。
格式:
{ $pullAll: { : [ , ... ], ... } }
举例:
为了演示,插入如下数据:
db.scores.save({_id:1, scores:[67, 89, 90, 87, 54, 100]});
下面更新操作从scores数组中删除分值为"67"和"54"的成绩:
db.scores.update({_id:1}, {$pullAll: {scores: [67, 54]}});
输出结果:
{
"_id" : 1.0,
"scores" : [
89.0,
90.0,
87.0,
100.0
]
}