我有一个包含3个字段的搜索表单：城市属性类型和房间所有字段都是选择类型输入。

如果我为每个字段选择值，我会得到正确的结果。

例如：

city= Los Angeles
property type = apartment
room = 3

但是如果只选择城市和属性类型，而不选择房间的值（假设空值为all). 我没有得到任何结果。我希望能在洛杉矶找到所有的公寓。

这是我到目前为止得到的wp查询。

if (isset($_GET[\'front-side-prop-search\'])){
    $args = array(
        \'posts_per_page\' => 9,
        \'post_type\'     => \'property\',
        \'meta_query\'    =>  array(
            \'relation \'     => \'AND\',
            array(
                \'key\'       => \'prop_city\',
                \'value\' => $city,
                \'compare\'       => \'=\',
                    \'meta_query\'    =>  array(
                    \'relation \'  => \'OR\',
                        array(
                            \'key\'       => \'prop_city\',
                            \'value\'     => \'All\',
                            \'compare\'   => \'NOT LIKE\',
                        ),
                    ),
                ),
            array(
                \'key\'       => \'prop_type\',
                \'value\' => $type,
                \'compare\'       => \'=\'
            ),
            array(
                \'key\'       => \'prop_rooms\',
                \'value\' => $rooms,
                \'compare\'       => \'=\'
            ),

        ),
    );
};

我确信我的wp\\U查询是错误的，请帮助我或给我指一篇可以帮助我解决这个问题的文章。

**

更新-我最终做了什么：

**

我按照tony的建议检查了每个变量，然后更改了compare 根据变量结果登录每个查询。

知道这一点compare => \'=\' 返回与该值相等的所有值。compare => \'!=\' 将返回不等于该值的所有内容。

这是我最终使用的代码：

$city = $_GET[\'field_59ae96d970a06\'];  //prop_city
$type = $_GET[\'field_59ec7533be002\'];  //prop_type
$rooms = $_GET[\'field_59ae9e2370a0b\'];


//check for each var if returns empty value or not

if($city == ""){
    $city_val = "!=";
}else{
    $city_val = "=";
};

if($type == "all types"){
    $type_val = "!=";
}else{
    $type_val = "=";
};

if($rooms == "all rooms"){
    $rooms_val = "!=";
}else{
    $rooms_val = "=";
};


//the query:

if (isset($_GET[\'front-side-prop-search\'])){

    $args = array(
        \'posts_per_page\' => 9,
        \'post_type\'     => \'property\',
        \'meta_query\'    =>  array(
            \'relation \'     => \'AND\',
            array(
                \'key\'       => \'prop_city\',
                \'value\' => $city,
                \'compare\'       => $city_val,
            ),
            array(
                \'key\'       => \'prop_type\',
                \'value\' => $type,
                \'compare\'       => $type_val,
            ),
            array(
                \'key\'       => \'prop_rooms\',
                \'value\' => $rooms,
                \'compare\'       => $rooms_val,
            ),

        ),
    );
};

if (isset($_GET[\'front-side-prop-search\'])){

 // test whether $city has a selected value, if so then args below: 

 // $city and $type selected

$args = array(
    \'posts_per_page\' => 9,
    \'post_type\'     => \'property\',
    \'meta_query\'    =>  array(
        \'relation \'     => \'AND\',
        array(
            \'key\'       => \'prop_city\',
            \'value\' => $city,
            \'compare\'       => \'=\',
                \'meta_query\'    =>  array(
                \'relation \'  => \'OR\',
                    array(
                        \'key\'       => \'prop_city\',
                        \'value\'     => \'All\',
                        \'compare\'   => \'NOT LIKE\',
                    ),
                ),
            ),
        array(
            \'key\'       => \'prop_type\',
            \'value\' => $type,
            \'compare\'       => \'=\'
        )
    ),
  );


// $city and $rooms

$args = array(
    \'posts_per_page\' => 9,
    \'post_type\'     => \'property\',
    \'meta_query\'    =>  array(
        \'relation \'     => \'AND\',
        array(
            \'key\'       => \'prop_city\',
            \'value\' => $city,
            \'compare\'       => \'=\',
                \'meta_query\'    =>  array(
                \'relation \'  => \'OR\',
                    array(
                        \'key\'       => \'prop_city\',
                        \'value\'     => \'All\',
                        \'compare\'   => \'NOT LIKE\',
                    ),
                ),
            ),
        array(
            \'key\'       => \'prop_rooms\',
            \'value\' => $rooms,
            \'compare\'       => \'=\'
        ),

    ),
);

// etc
};