根据数组字段大小对文档进行排序

Question

我正在尝试使用一个名为“empofthemonth”的数组的大小来对返回的每个字段进行排序，这些字段由他们当月获胜的员工数量返回。

这里是插入代码：

$db->users->insert(
    ["firstname" => "firstname1", 
     "lastname" => "test", 
     "email" => "test@email.org.uk", 
     "keyinfo" => 
        ["age" => 22,
         "gender" => "Male",
         "yearsemployed" => 1,
         "empofthemonth" => ["Apr"]]
     ]);

$db->users->insert(
    ["firstname" => "firstname2", 
     "lastname" => "test2", 
     "email" => "test@email.co.uk", 
     "keyinfo" => 
        ["age" => 24,
         "gender" => "Female",
         "yearsemployed" => 5,
         "empofthemonth" => ["Feb", "Mar"]]
     ]);

$db->users->insert(
    ["firstname" => "firstname3", 
     "lastname" => "test2", 
     "email" => "test@email.com", 
     "keyinfo" => 
        ["age" => 31,
         "gender" => "Female",
         "yearsemployed" => 2,
         "empofthemonth" => ["Jan", "May", "Jun"]]
     ]);

我知道aggregation 可能会被使用，但我无法计算出完整的语法。

总结查询结果应该是这个顺序：

1. firstname3（每月 3 个 emp）
2. 名字2 (2)
3. 名字1 (1)

Answer 1

我们需要$project我们的文档，然后按“大小”降序返回$size然后$sort每个文档。注意，要访问数组字段，我们需要使用"dot notation".

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

---

---

PHP 中的一切：

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