根据数组字段大小对文档进行排序

Question

我试图使用一个名为" empothemonth "的数组的大小来按每月获胜的员工数量对每个字段进行排序。

插入代码:

$db->users->insert(
    ["firstname" => "firstname1", 
     "lastname" => "test", 
     "email" => "[e-mail]", 
     "keyinfo" => 
        ["age" => 22,
         "gender" => "Male",
         "yearsemployed" => 1,
         "empofthemonth" => ["Apr"]]
     ]);
$db->users->insert(
    ["firstname" => "firstname2", 
     "lastname" => "test2", 
     "email" => "[e-mail]", 
     "keyinfo" => 
        ["age" => 24,
         "gender" => "Female",
         "yearsemployed" => 5,
         "empofthemonth" => ["Feb", "Mar"]]
     ]);
$db->users->insert(
    ["firstname" => "firstname3", 
     "lastname" => "test2", 
     "email" => "[e-mail]", 
     "keyinfo" => 
        ["age" => 31,
         "gender" => "Female",
         "yearsemployed" => 2,
         "empofthemonth" => ["Jan", "May", "Jun"]]
     ]);

我意识到聚合可能被使用，但我不能算出完整的语法。

查询结果应该是这样的顺序:

1. firstname3(每月3次)
2. firstname2 (2)
3. firstname1 (1)

Answer 1

我们需要$project我们的文档，并返回$size然后$sort每个文档按"大小"降序。注意，要访问数组字段，我们需要使用"点表示法"。

db.users.aggregate(
    [
        { "$project": { 
            "firstname": 1, 
            "lastname": 1, 
            "email": 1, 
            "keyinfo": 1, 
            "sz": { "$size": "$keyinfo.empofthemonth" } 
        }}, 
        { "$sort": { "sz": -1 } } 
    ]
)

---

---

PHP中的所有内容:

$db->users->aggregate(
    [
        [ "$project" => [ 
            "firstname" => 1, 
            "lastname" => 1, 
            "email" => 1, 
            "keyinfo" => 1, 
            "sz" => [ "$size" => "$keyinfo.empofthemonth" ]
        ]], 
        [ "$sort" => [ "sz" => -1 ] ] 
    ]
)