Laravel如何实现多个指定字段仅且必须填写其中一个的验证规则

你可以在原有required_without_all规则的基础上，补充Laravel内置的prohibits规则实现需求，该规则的作用是：只要当前字段有值，就禁止prohibits后声明的其他字段存在值，刚好满足「仅允许填写一个」的限制。

修改后的验证规则如下：

public function rules()
{
    return [
        "isFlat" => "required_without_all:isDetachedHouse,isTerrace,isSemiDetached|prohibits:isDetachedHouse,isTerrace,isSemiDetached",
        "isDetachedHouse" => "required_without_all:isFlat,isTerrace,isSemiDetached|prohibits:isFlat,isTerrace,isSemiDetached",
        "isTerrace" => "required_without_all:isFlat,isDetachedHouse,isSemiDetached|prohibits:isFlat,isDetachedHouse,isSemiDetached",
        "isSemiDetached" => "required_without_all:isFlat,isDetachedHouse,isTerrace|prohibits:isFlat,isDetachedHouse,isTerrace",
        "finishQuality" => [
            "required",
            Rule::in(["luxury", "standard", "economy"])
        ],
    ];
}

如果你使用的Laravel版本低于8.x（prohibits规则为8.x版本新增），可以通过闭包自定义验证实现相同效果：

public function rules()
{
    // 定义互斥字段集合
    $exclusiveFields = ['isFlat', 'isDetachedHouse', 'isTerrace', 'isSemiDetached'];
    // 统计已填写的互斥字段数量
    $filledExclusiveCount = count(array_filter(request()->only($exclusiveFields)));

    // 复用的互斥校验闭包
    $exclusiveValidate = function ($attribute, $value, $fail) use ($filledExclusiveCount) {
        if ($filledExclusiveCount > 1) {
            $fail('房屋类型仅允许选择一项');
        }
    };

    return [
        "isFlat" => [
            "required_without_all:isDetachedHouse,isTerrace,isSemiDetached",
            $exclusiveValidate
        ],
        "isDetachedHouse" => [
            "required_without_all:isFlat,isTerrace,isSemiDetached",
            $exclusiveValidate
        ],
        "isTerrace" => [
            "required_without_all:isFlat,isDetachedHouse,isSemiDetached",
            $exclusiveValidate
        ],
        "isSemiDetached" => [
            "required_without_all:isFlat,isDetachedHouse,isTerrace",
            $exclusiveValidate
        ],
        "finishQuality" => [
            "required",
            Rule::in(["luxury", "standard", "economy"])
        ],
    ];
}

内容的提问来源于stack exchange，提问作者Muhammad Hassan Javed