在mongodb中的subDocument数组上一起使用$ slice和$ regex [英] Using $slice with $regex together on subDocument array in mongodb

问题描述

我在mongo中遇到了问题.首先让我向您展示一个数据示例.这是我桌子上的记录.

Hi I am stuck on a problem in mongo. Let me first show you an example of the data. This is a record from my table.

{
    "_id": "3691149613248",
    "following": [{
    "content_id": "2584833593728",
    "date": "2015-08-20 12:46:55"
    }, {
    "content_id": "3693447751360",
    "date": "2015-09-11 12:17:55"
    }, {
    "content_id": "2582396936896",
    "date": "2015-09-12 07:04:02"
    }, {
    "content_id": "3697346507456",
    "date": "2015-09-14 09:56:03"
    }, {
    "content_id": "3697755500800",
    "date": "2015-09-16 10:05:51"
    }, {
    "content_id": "2589701320192",
    "date": "2015-09-16 10:51:19"
    }, {
    "content_id": "2585723555136",
    "date": "2015-09-16 11:40:26"
    }, {
    "content_id": "3695996668352",
    "date": "2015-09-16 12:50:25"
    }, {
    "content_id": "3694290368512",
    "date": "2015-09-16 12:50:33"
    }, {
    "content_id": "3691210127552",
    "date": "2015-09-16 13:02:57"
    }, {
    "content_id": "3694134958464",
    "date": "2015-09-16 13:06:17"
    }, {
    "content_id": "3697315148736",
    "date": "2015-09-17 06:58:35"
    }, {
    "content_id": "3692104837824",
    "date": "2015-09-17 12:19:12"
    }, {
    "content_id": "3693400309376",
    "date": "2015-09-22 05:43:04"
    }]
}

我想获取following数组，条件是仅特定记录要获取，即以限制和偏移量指定的前缀369和content_id的获取编号的content_ids.

I want to fetch following array with condition that only specific records to fetch i.e. content_ids with prefix 369 and fetch number of content_id specified in limit and offset.

我正在使用$slice来获取给定限制& following数组的偏移量.但是如何过滤content_id和$slice.

I am using $slice for fetching records for given limit & offset for following array. But how to filter content_id along with $slice.

我当前的查询

 db.collectionName.find({
    _id: "3691149613248"
}, {
    "following": {
    "$slice": [0, 10]
    }
});

这是使用限制&中指定的content_id提取following数组.抵消.但是，它正在提取所有content_id，包括前缀258& 369，但我只需要使用mongo查询使用带前缀369的content_id.

This is fetching following array with content_id that is specified in limit & offset. But it is fetching all content_id including prefix 258& 369 but I only need content_id with prefix 369 using mongo query.

任何人都可以帮忙吗?

推荐答案

您可以使用 $ unwind 和 $ match 与mongo 聚合以获得预期的输出，例如:

You can use combination of $unwind and $match with mongo aggregation to get expected output like:

db.collection.aggregate({
    $match: {
    "_id": "3691149613248"  // you can skip this condition if not required
    }
}, {
    $unwind: "$following"
}, {
    $match: {
    "following.content_id": {
        $regex: /^369/
    }
    }
}, {
    $group: {
    _id: "$_id",
    "following": {
        $push: "$following"
    }
    }
})

如果您要应用跳过和限制到上面的查询中，那么您可以像这样轻松地使用它:

If you want to apply skip and limit to above query then you can easily use it like:

db.collection.aggregate({
    $match: {
    "_id": "3691149613248" //use this if you want to filter out by _id
    }
}, {
    $unwind: "$following"
}, {
    $match: {
    "following.content_id": {
        $regex: /^369/
    }
    }
}, {
    $skip: 4  // you can set offset here
}, {
    $limit: 3 // you can set limit here
}, {
    $group: {
    _id: "$_id",
    "following": {
        $push: "$following"
    }
    }
})

编辑:

如果您使用的PHP版本低于5.4，则查询将为:

If you are using php version less than 5.4 then query will be as:

$search = "369";
$criteria = array(array("$match" => array("_id" => "3691149613248")),
    array("$unwind" => "$following"),
    array("$match" => array("following.content_id" => array("$regex" => new MongoRegex("/^$search/")))),
    array("$skip" => 4), array("$limit" => 3),
    array("$group" => array("_id" => "$_id", "following" => array("$push" => "$following"))));
$collection - > aggregate($criteria);

如果您使用的PHP版本大于5.3，则分别用[和]替换{和}括号.

If you are using PHP version greater than 5.3 then just replace { and } braces with [ and ] respectively.

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