如何使用mongodb在内部数组中搜索字符串? [英] How to search a string in inner array using mongodb?
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问题描述
如何在多维数组中搜索值，
例如我想在mongodb的以下数据中搜索example关键字
我曾经从命令中获取所有数据
How to search value in multidimensional array,
for example I want to search example keyword in the following data in mongodb
I used to fetch all data from command
>db.info.find()
{
"_id" : ObjectId("4f74737cc3a51043d26f4b90"),
"id" : "12345",
"info" : [
{
"sno" : 1,
"name" : "ABC",
"email" : "abc@example.com"
},
{
"sno" : 2,
"name" : "XYZ",
"email" : "xyz@example.com"
},
{
"sno" : 3,
"name" : "XYZ",
"email" : "xyz@demo.com"
},
{
"sno" : 4,
"name" : "ABC",
"email" : "abc@demo.com"
},
{
"sno" : 5,
"name" : "Rohan",
"email" : "rohan@example.com"
}
]
}
现在，要查找具有example的数据，我使用了命令
Now, to find data having example I used command
>db.info.find({"info.email":"example"})
它给出了
{
"_id" : ObjectId("4f74737cc3a51043d26f4b90"),
"id" : "12345",
"info" : [
{
"sno" : 1,
"name" : "ABC",
"email" : "abc@example.com"
},
{
"sno" : 2,
"name" : "XYZ",
"email" : "xyz@example.com"
},
{
"sno" : 3,
"name" : "XYZ",
"email" : "xyz@demo.com"
},
{
"sno" : 4,
"name" : "ABC",
"email" : "abc@demo.com"
},
{
"sno" : 5,
"name" : "Rohan",
"email" : "rohan@example.com"
}
]
}
但是我只想要5个子行中的3个
But I want only 3 out of 5 sub rows like
{
"_id" : ObjectId("4f74737cc3a51043d26f4b90"),
"id" : "12345",
"info" : [
{
"sno" : 1,
"name" : "ABC",
"email" : "abc@example.com"
},
{
"sno" : 2,
"name" : "XYZ",
"email" : "xyz@example.com"
},
{
"sno" : 5,
"name" : "Rohan",
"email" : "rohan@example.com"
}
]
}
推荐答案
我尝试了Map Reduce Function，它可以处理此类问题，代码如下:
I tried Map Reduce Function and it works on this type of problems the code is something like that:
编写地图功能
map=function ()
{
filter = [];
this.info.forEach(function (s) {if (/example/.test(s.email)) {filter.push(s);}});
emit(this._id, {info:filter});
}
编写归约函数
reduce=function(key, values) { return values;}
MapReduce函数
MapReduce Function
res=db.info.mapReduce(map,reduce,{out:{inline:1}})
输出看起来像:
"results" : [
{
"_id" : ObjectId("4f9a2de0ea4a65c3ab85a9d3"),
"value" : {
"info" : [
{
"sno" : 1,
"name" : "ABC",
"email" : "abc@example.com"
},
{
"sno" : 2,
"name" : "XYZ",
"email" : "xyz@example.com"
},
{
"sno" : 5,
"name" : "Rohan",
"email" : "rohan@example.com"
}
]
}
}
],
"timeMillis" : 1,
"counts" : {
"input" : 3,
"emit" : 3,
"reduce" : 0,
"output" : 3
},
"ok" : 1,
现在您可以从
printjson(res.results)
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