查看一个文档的一个键值comments为一个数组[“test1”,”test2”]：
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> db.post.findOne({"id":1})
{ "_id" : ObjectId("54a530c3ff0df3732bac1680"),
"id" : 1,
"name" : "joe",
"age" : 21,
"comments" : [
"test1",
"test2" ]
} > |
一、$push向数组末尾添加元素
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> db.post.update({"id":1},{$push:{"comments": "test3"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.post.findOne({"id":1})
{ "_id" : ObjectId("54a530c3ff0df3732bac1680"),
"id" : 1,
"name" : "joe",
"age" : 21,
"comments" : [
"test1",
"test2",
"test3" ]
} > |
使用$each一次性添加多个值：
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> db.post.update({"id":1},{$push:{"comments":{$each:["test4","test5","test6"]}}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.post.findOne({"id":1})
{ "_id" : ObjectId("54a530c3ff0df3732bac1680"),
"id" : 1,
"name" : "joe",
"age" : 21,
"comments" : [
"test1",
"test2",
"test3",
"test4",
"test5",
"test6" ]
} > |
二、用$pop删除数组中的元素
从数组末尾删除一个值：
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> db.post.update({"id":1},{$pop:{"comments":1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.post.findOne({"id":1})
{ "_id" : ObjectId("54a530c3ff0df3732bac1680"),
"id" : 1,
"name" : "joe",
"age" : 21,
"comments" : [
"test1",
"test2",
"test3",
"test4",
"test5" ]
} |
从数组开头删除一个值：
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> db.post.update({"id":1},{$pop:{"comments":-1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.post.findOne({"id":1})
{ "_id" : ObjectId("54a530c3ff0df3732bac1680"),
"id" : 1,
"name" : "joe",
"age" : 21,
"comments" : [
"test2",
"test3",
"test4",
"test5" ]
} > |
三、删除数组中一个指定的值：
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> db.post.update({"id":1},{$pull:{"comments":"test3"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.post.findOne({"id":1})
{ "_id" : ObjectId("54a530c3ff0df3732bac1680"),
"id" : 1,
"name" : "joe",
"age" : 21,
"comments" : [
"test2",
"test4",
"test5" ]
} > |
四、基于数组下标位置修改：
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> db.post.update({"id":1},{$set:{"comments.1":"test9"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.post.findOne({"id":1})
{ "_id" : ObjectId("54a530c3ff0df3732bac1680"),
"id" : 1,
"name" : "joe",
"age" : 21,
"comments" : [
"test2",
"test9",
"test5" ]
} > |
本文转自 bannerpei 51CTO博客，原文链接：http://blog.51cto.com/281816327/1598705，如需转载请自行联系原作者