How to check whether a text variable is equal to an Array-CodePudding

My requirement is to check whether a text variable is equal or not to an mysql output array.

The mysql output array I have taken as follows,

$connect = mysqli_connect("localhost", "root", "", "newbooks");
$query = "SELECT book_name FROM takenbooks order by ID DESC";
$result = mysqli_query($connect, $query);
while( $row = mysqli_fetch_assoc( $result)){
    $avail_books[] = $row['book_name']; // Inside while loop
}

Now I need to check whether user have entered any book from which included in above array.So I have implemented as below.

$(document).ready(function(){
  $('#insert_form').on("submit", function(event){  
    event.preventDefault();
    $('#book_name').val()=$book_required;


    if(in_array($book_required,$avail_books))
    {
      alert("Not Available");
    }
    else{
      $.ajax({

        url:"books.php",  
        method:"POST",  
        data:$('#insert_form').serialize(),  
        beforeSend:function(){  
          $('#insert').val("Inserting");  
        },  
        success:function(data){  
          $('#insert_form')[0].reset();  
          $('#add_data_Modal').modal('hide');  
          $('#employee_table').html(data);  
        }  

      });  
    }
  }
}

But this is not working. Can someone show where I have messed this?

CodePudding user response：

There can be other ways to accomplish what you want.

For example, use the following query:

SELECT count(*) FROM takenbooks where book_name = ?

But for How to check whether a text variable is equal to an Array and based on your original code, the normal way will be to pass the user input data (I believer is $('#book_name').val()) thru ajax to a PHP file to check whether this data is in the array , then return the result back (or do further processing)

For the HTML

<script
  src="https://code.jquery.com/jquery-3.6.0.js"
  integrity="sha256-H K7U5CnXl1h5ywQfKtSj8PCmoN9aaq30gDh27Xc0jk="
  crossorigin="anonymous"></script>


<form id=insert_form>
<input type=text id="book_name">
<input type=submit>
</form>

<script>
$(document).ready(function(){
  $('#insert_form').on("submit", function(event){  
   event.preventDefault();

  $.ajax({
   type: "POST",
   url: 'checkdata.php',
   data: {data1: $('#book_name').val()},
   success: function(data){
   alert(data);
   },
    error: function(xhr, status, error){
    console.error(xhr);
   }
  });
 })
})
 </script>

For the PHP (checkdata.php)

<?php
 
if (isset($_POST["data1"])){

$connect = mysqli_connect("localhost", "root", "", "newbooks");
$query = "SELECT book_name FROM takenbooks order by ID DESC";
$result = mysqli_query($connect, $query);

while( $row = mysqli_fetch_assoc( $result)){
    $avail_books[] = $row['book_name']; // Inside while loop
}

   if(in_array($_POST["data1"],$avail_books)) {
     echo "Not Available";
     } else {

    // Place insert query here

     echo "New Record inserted";

    }
}

?>

CodePudding user response：

It might have some Syntax error but thats the basic concept of what you are trying to achieve. Someones enters text, script searches the database and returns the results.

<html>
<body>
<form action="" method="POST">
 <input type="text" name"book" required placeholder="Type the name of the Book" />
 <input type="submit" value="Search Book" />
</form>

<div><h2>Results:</h2>

<?php

if(isset($_POST['book'] && !empty($_POST['book'])){

   mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

   $connect = new mysqli("localhost", "root", "", "newbooks");
   $stmt = $mysqli->prepare("SELECT ID, book_name FROM takenbooks WHERE book_name LIKE ? ORDER BY ID DESC;");
   $stmt->bind_param("s", "%"   $_POST['book']   "%");
   $stmt->execute();
   $result = $stmt->get_result();
  
   while ($row = $result->fetch_assoc()) {
      echo '<p>Book \"' . $row['book_name'] . '\" was found.<br/></p>';
   }
}

?>
</div>
</body>
</html>

CodePudding user response：

You can first get the list of books once, then write a Javascript array from which to search for the entered book name. (This may not be practical if the list of books changes quite often, or the list is extremely long.)

<?php

$connect = mysqli_connect("localhost", "root", "", "newbooks");
$query = "SELECT book_name FROM takenbooks order by ID DESC";
$result = mysqli_query($connect, $query);
$avail_books = [];
while( $row = mysqli_fetch_assoc( $result)){
    $avail_books[] = $row['book_name']; // Inside while loop
}

?>
<!DOCTYPE html>
<html>
<body>
<form id="insert_form">
  Book name: <input type="text" name="book_name">
  <input type="submit" value="Check for availability">
</form>
<div id="available"></div>
<script>

const avail_books = <?php json_encode($avail_books); ?>;

document.querySelector('#insert_form').addEventListener(function (evt) {
  evt.preventDefault();

  let book_name = evt.target.book_name.value;
  let not_available = (-1 === avail_books.indexOf(book_name))? 'not': '';
  document.querySelector('#available').innerHTML = book_name   " is "   not_available   " available.";
});
</script>    

</body>
</html>

PHP, on the server, gets the books and stores the list in a PHP array. And when writing out HTML and Javascript use PHP to write out a Javascript avail_books array containing the book names retrieved from the database.

Now the server can send the client the HTML/Javascript code for rendering. Once loaded in the browser, and if you "View Source", the Javascript code will look something like this:

const avail_books = ["To Kill a Mockingbird", "Animal Farm", "Atlas Shrugged"];

With that the user can check the list of books without having to send a query to the server with every inquiry. It's faster and uses less resources.