合并下拉php中的重复值

Question

I would like to merge duplicate values that i have in my drop down list, i dont want to use array_unique because it deletes my second duplicate value. The way my program works is if you select a location it will populate my second drop down accordingly.

If you look at the picture provided you can see two duplicate entries Rosebank when i click the first rosebank it will only show me on provider in my second drop down but when i click on the second rosebank it shows me all the providers with the location rosebank. I would like to know if there is a way i can merge the two duplicates so that it will show me all the providers when i click rosebank and it should only show one rosebank.

Here is my code without array_unique:

    <label for="select-service">
                <strong>Enter a Location:</strong>
            </label>
            <select class="form-control" id="select-location" class="col-xs-12 col-sm-4 form-control" required>
                <option value="">Select Location</option>



                 <?php


            foreach($appointment_locations as $location) {



             $LocationsArray = explode(",", $location->notes);

              foreach($LocationsArray as $singleLocation):
                 ?>

                <option value="<?=$singleLocation ?>"><?=$singleLocation  ?></option>                  

                <? endforeach;

                 };?>

            </select>

and here is what i have tried with array_unique, it successfully deletes the duplicates but as i said earlier, it will only show me one value in my next drop down and not all

  <label for="select-service">
                <strong>Enter a Location:</strong>
            </label>
            <select class="form-control" id="select-location" class="col-xs-12 col-sm-4 form-control" required>
                <option value="">Select Location</option>



                 <?php

          foreach(array_unique($appointment_locations) as $location) {
           // foreach($appointment_locations as $location) {



             $LocationsArray = explode(",", $location->notes);

              foreach($LocationsArray as $singleLocation):
                 ?>

                <option value="<?=$singleLocation ?>"><?=$singleLocation  ?></option>                  

                <? endforeach;

                 };?>

            </select>

here is my var_dump

                         array(2) {
  [0]=>
  object(stdClass)#28 (2) {
    ["id"]=>
    string(1) "4"
    ["notes"]=>
    string(29) "Randburg, Greenside, Rosebank"
  }
  [1]=>
  object(stdClass)#29 (2) {
    ["id"]=>
    string(1) "8"
    ["notes"]=>
    string(8) "Rosebank"
  }
}

Answer 1

This should do it:

Get the unique locations by storing them in an array as the keys:

$unique_locations = [];
foreach(array_unique($appointment_locations) as $location) {
    foreach(explode(",", $location->notes) as $singleLocation) {
        $unique_locations[$singleLocation] = 1;
    }
}
?>

Use array_keys, array_map and implode to put it all together:

...
<select>
    <?= implode('', array_map(function($location) { return "<option value='$location'>$location</option>"; }, array_keys($unique_locations)))  ?>
</select>
...