如何使用mongodb 3.0.0检索数组内的对象(如果匹配给定条件)

问题描述

如果要匹配给定条件，我想从数组中投影所有对象.

I want to project all the objects from an array, if it matches the given condition.

我有以下数据

{
    _id : 1,
    em : '[e-mail]',
    name : 'NewName',
    od : 
    [
        {
            "oid" : ObjectId("1234"),
            "ca" : ISODate("2016-05-05T13:20:10.718Z")
        },
        {
            "oid" : ObjectId("2345"),
            "ca" : ISODate("2016-05-11T13:20:10.718Z")
        },
        {
            "oid" : ObjectId("57766"),
            "ca" : ISODate("2016-05-13T13:20:10.718Z")
        }
    ]       
},
{
    _id : 2,
    em : '[e-mail]',
    name : 'NewName2',
    od : 
    [
        {
            "oid" : ObjectId("1234"),
            "ca" : ISODate("2016-05-11T13:20:10.718Z")
        },
        {
            "oid" : ObjectId("2345"),
            "ca" : ISODate("2016-05-12T13:20:10.718Z")
        },
        {
            "oid" : ObjectId("57766"),
            "ca" : ISODate("2016-05-05T13:20:10.718Z")
        }
    ]       
}

我想从od数组中获取所有对象，如果'od.ca'介于范围之内(如果大于等于5月且小于等于15日).

I want to get all the objects from od array, if 'od.ca' comes between range say, if greater than 10th may and less than 15th may.

我尝试使用mongodb的聚合方法，但对这种方法不熟悉.我的查询如下.

I tried using aggregate method of mongodb and I am new to this method. My query is as given below.

db.userDetail.aggregate(
        {
            $match: 
            {
                'od.ca': 
                {
                    '$gte': '10/05/2016',
                    '$lte': '15/05/2016' 
                },
                lo: { '$ne': 'd' }
            }
        },
        {
            $redact:
            {
                $cond: 
                {
                    if: 
                    {
                        $gte: [ "$$od.ca", '10/05/2016' ],
                        $lte : ["$$od.ca" , '15/05/2016']
                    },
                    then: "$$DESCEND",
                    else: "$$PRUNE"
                }
            }
        })

当我尝试使用此命令时，出现错误:-

When I am trying to use this command, getting error :-

由于我使用的是mongodb 3.0.0，因此无法使用 $ fiter .因此，我尝试使用 $ redact .

Since I am using mongodb 3.0.0 I can not use $fiter. So I tried using $redact.

有人可以告诉我我在做什么错吗?查询正确吗?

Can someone tell me what wrong I am doing? Is the query correct?

推荐答案

查询说明:

1. $ match-为条件匹配文档-限制要处理的文档
2. $ unwind-从输入文档中构造 od 数组字段，以输出每个元素的文档.每个输出文档都是输入文档，其中array字段的值被元素替换.
3. $ match-为条件匹配文档
4. $ group-在我们的例子中这与$ unwind相反-因此我们正在重新创建结果数组

1. $match - match documents for criteria - limit documents to process
2. $unwind - econstructs od array field from the input documents to output a document for each element. Each output document is the input document with the value of the array field replaced by the element.
3. $match - match documents for criteria
4. $group - this is opposite of $unwind in our case - so we are recreating results array

如果您希望获得这样的文档:

If you are expecting document like this:

{
    "_id" : 2,
    "od" : [{
            "oid" : 1234,
            "ca" : ISODate("2016-05-11T13:20:10.718Z")
        }, {
            "oid" : 2345,
            "ca" : ISODate("2016-05-12T13:20:10.718Z")
        }
    ]
}, {
    "_id" : 1,
    "od" : [{
            "oid" : 2345,
            "ca" : ISODate("2016-05-11T13:20:10.718Z")
        }, {
            "oid" : 57766,
            "ca" : ISODate("2016-05-13T13:20:10.718Z")
        }
    ]
}

您可以使用下面的查询:

you can use query bellow:

db.userDetail.aggregate([{
            $match : {
                "od.ca" : {
                    $lt : new Date(new Date().setDate(new Date().getDate() + 2)),
                    $gte : new Date(new Date().setDate(new Date().getDate() - 4))
                }
            }
        }, {
            $unwind : "$od"
        }, {
            $match : {
                "od.ca" : {
                    $lt : new Date(new Date().setDate(new Date().getDate() + 2)),
                    $gte : new Date(new Date().setDate(new Date().getDate() - 4))
                }
            }
        }, {
            $group : {
                _id : "$_id",
                od : {
                    $push : "$od"
                }
            }
        }
    ])

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