Laravel模型关联链式查询无匹配结果时如何跳过对应if过滤条件

• 现有代码的核心问题是Laravel查询构造器为可变对象：你在if判断条件中直接对原查询对象$matches调用whereRelation后做计数，不管后续判断是否通过，这个过滤条件已经被写入原查询对象，只要某一个条件无匹配结果，该条件就会残留在查询逻辑中，最终导致返回空结果。

判断过滤条件是否生效时，克隆一份当前的查询构造器做计数校验，避免污染原查询，只有对应条件有匹配结果时，才给原查询追加该过滤规则，修复后代码如下：

$matches = Property::with(['media', 'address', 'customer'])->where([
    'agency_id' => session('agency_id'),
    'purpose' => $propertyRequirement->purpose,
    'category_id' => $propertyRequirement->category_id,
    'sub_category_id' => $propertyRequirement->sub_category_id,
    'urgency' => $propertyRequirement->urgency
])
->whereRelation('address', 'city', $propertyRequirement->propertyRequirementDetail->city)
->whereBetween('price', [$propertyRequirement->min_price, $propertyRequirement->max_price])
->whereBetween('area', [$propertyRequirement->min_area, $propertyRequirement->max_area]);

$filterCounter = 9;

// location条件校验
if (!empty($propertyRequirement->propertyRequirementDetail->location)) {
    // 克隆查询做计数，不污染原对象
    $tempQuery = clone $matches;
    if ($tempQuery->whereRelation('address', 'location', $propertyRequirement->propertyRequirementDetail->location)->count() > 0) {
        $matches->whereRelation('address', 'location', $propertyRequirement->propertyRequirementDetail->location);
        $filterCounter++;
    }
}

if ($propertyRequirement->category_id === 1) {
    // 最小卫生间数校验
    if (!empty($propertyRequirement->propertyRequirementDetail->min_bathrooms)) {
        $tempQuery = clone $matches;
        if ($tempQuery->whereRelation('propertyDetail', 'bathrooms', '>=', $propertyRequirement->propertyRequirementDetail->min_bathrooms)->count() > 0) {
            $matches->whereRelation('propertyDetail', 'bathrooms', '>=', $propertyRequirement->propertyRequirementDetail->min_bathrooms);
            $filterCounter++;
        }
    }
    // 最大卫生间数校验
    if (!empty($propertyRequirement->propertyRequirementDetail->max_bathrooms)) {
        $tempQuery = clone $matches;
        if ($tempQuery->whereRelation('propertyDetail', 'bathrooms', '<=', $propertyRequirement->propertyRequirementDetail->max_bathrooms)->count() > 0) {
            $matches->whereRelation('propertyDetail', 'bathrooms', '<=', $propertyRequirement->propertyRequirementDetail->max_bathrooms);
            $filterCounter++;
        }
    }
    // 最小房间数校验
    if (!empty($propertyRequirement->propertyRequirementDetail->min_rooms)) {
        $tempQuery = clone $matches;
        if ($tempQuery->whereRelation('propertyDetail', 'rooms', '>=', $propertyRequirement->propertyRequirementDetail->min_rooms)->count() > 0) {
            $matches->whereRelation('propertyDetail', 'rooms', '>=', $propertyRequirement->propertyRequirementDetail->min_rooms);
            $filterCounter++;
        }
    }
    // 最大房间数校验
    if (!empty($propertyRequirement->propertyRequirementDetail->max_rooms)) {
        $tempQuery = clone $matches;
        if ($tempQuery->whereRelation('propertyDetail', 'rooms', '<=', $propertyRequirement->propertyRequirementDetail->max_rooms)->count() > 0) {
            $matches->whereRelation('propertyDetail', 'rooms', '<=', $propertyRequirement->propertyRequirementDetail->max_rooms);
            $filterCounter++;
        }
    }
    // 停车位校验
    if (!empty($propertyRequirement->propertyRequirementDetail->parking_space)) {
        $tempQuery = clone $matches;
        if ($tempQuery->whereRelation('propertyDetail', 'parking_space', $propertyRequirement->propertyRequirementDetail->parking_space)->count() > 0) {
            $matches->whereRelation('propertyDetail', 'parking_space', $propertyRequirement->propertyRequirementDetail->parking_space);
            $filterCounter++;
        }
    }
    // 建造年份校验
    if (!empty($propertyRequirement->propertyRequirementDetail->year_build)) {
        $tempQuery = clone $matches;
        if ($tempQuery->whereRelation('propertyDetail', 'year_build', $propertyRequirement->propertyRequirementDetail->year_build)->count() > 0) {
            $matches->whereRelation('propertyDetail', 'year_build', $propertyRequirement->propertyRequirementDetail->year_build);
            $filterCounter++;
        }
    }
}

// 后续可正常调用 $matches->get() 获取结果

内容的提问来源于stack exchange，提问作者Abdul Rehman