Question

我有两个名为“成分”和“金额”的表。每种成分都有一个称为数量的关系列，该列可以包含一个或多个数量的对象。

我想做的是循环获取所有成分，然后也获取所有这些成分的量。但是，我注意到，当我使用查询来获取金额时，这会大大减慢该过程，并且我无法获取所有成分（900多种）的金额，服务器只会超时。

有没有一种方法可以获取某种成分的所有金额而无需执行第二次for循环？最终，我要返回所有成分及其所含的量。

这是代码

try {
$query = new ParseQuery("Ingredient");
$query->descending("name");
$query->limit(1000); 
$results = $query->find();

for ($i = 0; $i < count($results); $i++) { 
    $object = $results[$i];
    $ingredient = new Ingredient($object->getObjectId(), $object->get('name'), $object->get('category'), $object->get('KH'), $object->get('EW'), 
    $object->get('FE'), $object->get('ALK'), $object->get('amounts')->_encode());
    array_push($old_values_array, $ingredient);

    $relation = $object->get('amounts');
    $query1 = $relation->getQuery();

    $results1 = $query1->find();

    for ($j = 0; $j < count($results1); $j++) { 
        //echo "Got here in loop 2";
        $object2 = $results1[$j];
        $id = $object2->getObjectId();
        $name = $object2->get('name');
        $grams = $object2->get('grams');

        $amount = new Amount($id, $name, $grams);
        array_push($amounts_array, $amount);  
     }   

}

Answer 1

one workaround would be to add a pointer to ingredients in your Amount parse class. Hence, you can query all 'Amounts' related to that ingredients at once and with one query.

-- If you don't know the max number of amounts for an ingredients, you can first count and the make another query to find them.

$ingredient = ...;

$query= new ParseQuery("Ingredient")->equalsTo('ingredient',$ingredient);

$amountCount=$query->count();
$amounts=$query->limit($amountCount)->find();

apologies if my PHP syntax might be wrong.

Parse.com，无法在for循环中使用query-> find（）获取数据

1 个答案: