如何显示错误并不允许以PHP形式提交两个输入

Question

One my form I have the option to choose from a select box, or to manually enter the information.

I want to prevent user from entering both. They should either choose from the select OR enter manually if their selection is not already there.

html code

<div class="row">
                <div class="form-group col-sm-4">
                  <div class="row">
                    <div class="col-sm-3">
                        <label for="selectComplvl" class="regions" >Region</label></div>
                    <div class="col-sm-8">
                      <select class="form-control regionbox" id="region" value="" name="region">
                        <option>---Select---</option>
                        <?php
                          $region_sql = "SELECT * FROM `regions`";
                          $region_res = mysqli_query($con, $region_sql);
                          if(mysqli_num_rows($region_res) > 0){
                             while($region_row = mysqli_fetch_array($region_res)){
                                  echo "<option value='".$region_row[id]."'>".$region_row[region]."</option>";
                              } 
                          }

                        ?>

                      </select>
                      <div class="help-block with-errors"></div>
                    </div>
                  </div>
                </div>

                <div class="form-group col-sm-4">
                  <div class="row">
                    <div class="col-sm-4">
                        <label for="feisEntered" class="feis">Feis Entered</label></div>
                    <div class="col-sm-8">
                      <select class="form-control feisbox" id="feisEntered" name="feisEntered">
                        <option>First choose a Region</option>

                      </select>
                      <div class="help-block with-errors"></div>
                    </div>
                  </div>
                </div>

                <div class="form-group col-sm-4">
                  <div class="row">
                    <div class="col-sm-3">
                        <label for="feisEntered" class="enterfeis">Or Enter</label></div>
                    <div class="col-sm-8">
                      <input id="inputfeis" type="text" name="feisEntered" class="form-control" placeholder="Feis name - MM/DD/YYYY">
                      <div class="help-block with-errors"></div>
                    </div>
                  </div>
                </div>
            </div>

And my query:

if(isset($_POST['submit'])){  
    $dancer=$_POST['dancer'];
    $dancer = mysqli_real_escape_string($con,$dancer);
    $level=$_POST['level'];
    $level = mysqli_real_escape_string($con,$level);
    $feisEntered=$_POST['feisEntered'];
    $feisEntered = mysqli_real_escape_string($con,$feisEntered);
    $danceName=$_POST['danceName'];
    $danceName = mysqli_real_escape_string($con,$danceName);
    $compNum=$_POST['compNum'];
    $compNum = mysqli_real_escape_string($con,$compNum);
    $competitor = $_POST['competitor'];
    $competitor = mysqli_real_escape_string($con,$competitor);
    $danceScore = $_POST['danceScore'];
    $danceScore = mysqli_real_escape_string($con,$danceScore);
    $placement = $_POST['placement'];
    $placement = mysqli_real_escape_string($con,$placement);
    $firstScore = $_POST['firstScore'];
    $firstScore = mysqli_real_escape_string($con,$firstScore);
    $secondScore = $_POST['secondScore'];
    $secondScore = mysqli_real_escape_string($con,$secondScore);
    $thirdScore = $_POST['thirdScore'];
    $thirdScore = mysqli_real_escape_string($con,$thirdScore);
    $judge = $_POST['judge'];
    $judge = mysqli_real_escape_string($con,$judge);
    $comments = $_POST['comments'];
    $comments = mysqli_real_escape_string($con,$comments);


$query = "INSERT INTO reports (user_id, dancer_id1, dancer_name, competition_level1, feis_entered, dance_name1, competition_number1, number_competitors1, dancer_score1, dancer_placement1, firstpl_score1, 2ndpl_score1, 3rdpl_score1, judge_name1, judge_comment1) VALUES ('$id','$dancerID', '$dancer', '$level', '$feisEntered', '$danceName', '$compNum', '$competitor', '$danceScore', '$placement', '$firstScore', '$secondScore', '$thirdScore', '$judge', '$comments')";

     $result = mysqli_query($con, $query);
}

So what I want to happen is a error message appears if they fill out both saying "Please choose only one". That way only one enters into database.

Answer 1

In your HTML document, you should use Javascript to validate the user input before submitting the form to the PHP script. Then, in the PHP script, you should double-check that values were not received for both the select and the input (this could happen if the user does not have Javascript enabled, or they somehow bypass the validation) and determine what you want to do in that case (select one over the other, or exit with an error).

Answer 2

Never rely on just JS to validate input. Use JS to implement the behavior you speak of and then handle all possible outcomes in PHP. If someone is fiddling with your JS and bypasses the behavior you implement, you need to be able to handle that in your PHP code as well to make sure DB doesnt get unexpected input and break everything. Just like Justin said above, you could select one or the other, or throw an error. I recommend throwing an error and telling the user to make sure they have JS enabled.