Question

我正在尝试在PHP中创建一个Map-Reduce命令，其中完全的功能与纯JavaScript相同，但结果却不尽相同。我在PHP中有 null 值： - （

我有“employees”集合，每位员工都有一个他/她所属的“部门”列表。

所以 Javascript map-reduce代码（有效）可以按部门获得员工人数：

map = function() {
    if (!this.department)   {
        return;
    }
    for (i in this.department)  {
        emit(this.department[i], 1);
    };
};

reduce = function(key, values) {
    var total = 0;

    for (i in values)   {
        total += values[i];
    };

    return total;
};

retorno = db.runCommand({
    "mapreduce": "employees",
    "map": map,
    "reduce": reduce,
    "out": "employees_by_department"
});
if (retorno.ok != 1)    {
    print(retorno.errmsg);
};

resultado = db.employees_by_department.find();
while ( resultado.hasNext() ) {
    printjson( resultado.next() );
}

等效的 PHP代码（带有 null 值）将是：

<?php
try {
    $connection = new MongoClient( "mongodb://localhost" ); 
    $db = $connection->selectDB("employees");
} catch (Exception $e) {
    printf("Error: %s: %s\n", "Error al conectarse a MongoDB: ",  $e->getMessage());
    die();
}


$map = new MongoCode("function() {
    if (!this.department)   {
        return;
    }
    for (i in this.department)  {
        emit(this.department[i], 1);
    };
};");

$reduce = new MongoCode("reduce = function(key, values) {
    var total = 0;

    for (i in values)   {
        total += values[i];
    };

    return total;
};");

$retorno = $db->command(array(
    "mapreduce" => "employees",
    "map" => $map,
    "reduce" => $reduce,
    "out" => "employees_by_department_php"
    ));
if ($retorno["ok"] =! 1)    {
    print($retorno["errmsg"]);
}
else {
    $resultado = $db->selectCollection("employees_by_department_php")->find();
    foreach($resultado as $dep) {
        printf("_id: \"%s\", value: %d\n", $dep["_id"], $dep["value"]);
    }
}

?>

有什么想法吗？

Answer 1

UUpppss !!解决了！问题是拼写错误（复制粘贴问题）： - |

在PHP中，reduce函数的第一行是

$reduce = new MongoCode("reduce = function(key, values) {

应该是

$reduce = new MongoCode("function(key, values) {

MongoDB MapReduce在PHP中返回空值（但在Javascript中工作）

1 个答案: