wp_query show all values

Question

I have a search form with 3 fields: city porperty type and rooms all fields are select type inputs.

If I select values for each of the fields I get the correct result.

for example:

city= Los Angeles
property type = apartment
room = 3

but if choose only city and property type and dont choose a value for rooms (lets say that the empty value is all). I dont get any result. I would expect to get all apartmnetns in L.A.

this is my wp query I got so far.

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'       => '='
            ),

        ),
    );
};

I am sure that my wp_query is wrong, please help me or point me to an article that could help me solve this issue.

**

Update - What I finaly did:

**

I checked every variable as tony suggested, than I changed the compare sign on each query depending the variable result.

Knowing that compare => '=' returns all the values that are equal to the value. compare => '!=' will return everything that is not equal to the value.

this is the code i eventually used:

$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,
            ),

        ),
    );
};

Answer 1

The example below just changes what args is based on your 3 input fields. This eliminates the need to check for these values (and using "all" for value). I'm sure some combination of logical operators for compare and relation would do the job but this works too.

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
};