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Valentina
Asked: 2022-04-14 07:10:10 +0800 CST 2022-04-14 07:10:10 +0800 CST

How to avoid correct answer, when the information sent is false Ajax | PHP?

  • 772

The following code allows me to enter new records when there is no one idto update, so far it works fine, but trying to update a record that does not exist, for example id 20when in my data table I only have 5 records that go consecutively from id 1until the id 5.

 <?php
    if (isset($_POST['ajaxData'])) {
        $id = $_POST["item_id"];
        $nombre_cliente = $_POST["nombre_cliente"];

        if (empty($_POST['nombre_cliente'])){
            echo json_encode(['status'=> false, 'message'=> ["nombre_cliente" =>"Por favor, ingresé el nombre del cliente para continuar."]]);
            exit;
        }
        
        if($id != '') {
            $stmt = $con->prepare("UPDATE cliente
                                    SET
                                        nombre_cliente = ?
                                    WHERE id_cliente = ?");
            $stmt->bind_param("si",
                                $nombre_cliente,
                                $id
                            );
            if ($stmt->execute()) {
                echo json_encode(['status'=> true, 'message'=>"<strong>Los datos se actualizaron correctamente.</strong>"]);
                exit;
            } else {
                echo json_encode(['status'=> false, 'message'=>"<strong>Lo sentimos, pero no podemos procesar su solicitud. Inténtalo más tarde.</strong>"]);
                exit;
            }
        } else {
            $stmtAdd = $con->prepare("INSERT INTO cliente (nombre_cliente) VALUES (?)");
            $stmtAdd->bind_param("s",$nombre_cliente);
            if ($stmtAdd->execute()) {
                echo json_encode(['status'=> true, 'message'=>"<strong>Nuevo cliente registrado correctamente.</strong>"]);
                exit;
            } else {
                echo json_encode(['status'=> false, 'message'=>"<strong>Lo sentimos, pero no podemos procesar su solicitud. Inténtalo más tarde.</strong>"]);
                exit;       
            }
        }

    }
?>

So when it sent the update saying id 20that it doesn't exist, ajax, it gives me a statement that the data was updated correctly, when this shouldn't happen, because it's data that doesn't exist, it should send me the message false, and not the true.

This is my ajax code:

$(function() {
    var frm = $('#ajaxData');
    frm.submit(function(e){
        //$('.error', '#resetform').remove();
        e.preventDefault();
        var formData = frm.serialize();
        formData += '&' + $('#submit_data').attr('name') + '=' + $('#submit_data').attr('value');
        
        var url = "update_cliente.php";
        $.ajax({
            type: frm.attr('method'),
            url: url,
            data: formData,
        })
        .done(function(data) {
            let res = JSON.parse(data);
            // si es true el estado
            if(res.status){
                $('.success').fadeIn();
                $('.success').html(res.message).delay(8000).fadeOut(8000);
                $(frm)[0].reset();
                $(frm).hide();
                setTimeout(function(){
                    location.href = 'cliente.php';
                },9000);
            } else {
                for (let name in res.message) {
                    $('.error').remove();
                    let msg = '<span class="error">' + res.message[name] + '</span>';
                    $(msg).insertAfter($('[name=' + name + ']', '#ajaxData'));
                    $('.error').fadeIn().delay(5000).fadeOut(5000);
                }
            }
        })
        .fail(function() {
            $('.warning').fadeIn();
            $('.warning').html(textStatus).delay(3000).fadeOut(3000);
        })
    });
});

How can I solve this error? Is it an Ajax error or an PHP code approach?

php

1 Answers

  1. Best Answer

    The problem is that this alone does not work to know if an update has occurred:

    if ($stmt->execute()) { // ...

    The method execute()returns truewhen there is no error executing a query. But a query with a WHEREwhose criteria isn't met isn't a bad query, it's just a query that doesn't return anything or does nothing or doesn't really change anything.

    That's why you should also check the affected rows with affected_rows.

    The same goes for the INSERTand the DELETE. Only when it isaffected_rows greater than the , the or an eventual .0UPDATEINSERTDELETE

    To apply what we've said, you can modify your UPDATEe blocks INSERTlike this:

    In the UPDATE:

            if ($stmt->execute() && $stmt->affected_rows > 0) {
            echo json_encode(['status'=> true, 'message'=>"<strong>Los datos se actualizaron correctamente.</strong>"]);
            exit;
        } else {
            echo json_encode(['status'=> false, 'message'=>"<strong>Lo sentimos, pero no podemos procesar su solicitud. Inténtalo más tarde.</strong>"]);
            exit;
        }

    And in the INSERT:

            if ($stmtAdd->execute() && $stmtAdd->affected_rows > 0) {
            echo json_encode(['status'=> true, 'message'=>"<strong>Nuevo cliente registrado correctamente.</strong>"]);
            exit;
        } else {
            echo json_encode(['status'=> false, 'message'=>"<strong>Lo sentimos, pero no podemos procesar su solicitud. Inténtalo más tarde.</strong>"]);
            exit;       
        }

    It should be said that a UPDATEthat was based on the same data that already exists would also return 0in affected_rows. For example, if the current name is Pedroand you send it to update it, Pedrothe query is tried, but it returns 0affected rows. The DBMS is not stupid, I imagine that somehow it verifies that the data to be set as new is different from the one that already exists before confirming the UPDATE. Of course, if there are other column(s) to update, with a value other than those that exist, even if Pedroit is the same, the UPDATE will occur because there is something different in that other column(s).

    In any case, perhaps it would be convenient to avoid sending useless queries to the server from the client, such as ordering to update a record that does not exist. But that is another business...

    • 3