PHP: Validate data in Update form before submitting to database - php

Question

I'm still very new to php and form validation. I am currently trying to create an update form that validates before submitting the data to the database. So far I have successfully managed to update the data in the database when submitting the form.
But now I am trying to validate the data and make sure that the 4 fields are filled in and not left blank, if some of the form fields are left blank then I need the form to reload with what was already filled in on the form previously.
I have started adding in form validation into the script below but this is script I have successfully used for adding new data to a database. I'm having trouble trying to wrap my head around what I need to change to make it work for an UPDATE query. Thanks in advance
The only fields i need to update in the form is the description, img_path, location and payment.
<?php
$mysqli = new mysqli("localhost", "root", "", "etrading");
session_start(); //start session
//Check that a product ID is specified for the page
if (isset($_GET['ItemID'])) {
$productID = $_GET['ItemID'];
}else{
header("Location: index.php");
}
if (isset($_POST['Name'])) {
$Name = $_POST['Name'];
$Description = $_POST['Description'];
$img_path = $_POST['img_path'];
$Quantity = $_POST['Quantity'];
$Category = $_POST['Category'];
$Location = $_POST['Location'];
$Saletype = $_POST['Saletype'];
$Price = $_POST['Price'];
$Duration = $_POST['Duration'];
$Payment = $_POST['Payment'];
$updateQuery = "UPDATE item SET Description = '$Description', img_path = '$img_path', Location = '$Location', Payment = '$Payment' WHERE ItemID= $productID";
$mysqli->query($updateQuery);
echo ("Product successfully updated");
}
$query = "SELECT * FROM item WHERE ItemID = $productID";
$result = $mysqli->query($query);
if($result->num_rows > 0) {
$data = $result->fetch_array(MYSQLI_BOTH);
//prepare input data in an array
$updatedata = array($Description, $img_path, $Location, $Payment);
//prepare error list
$errors = array ();
//Validation tests and store list
if ($Description == "" || $img_path == "" || $Location == "" || $Payment == "" ) {
array_push($errors, "All form fields must be filled out before submitting.");
}
//if errors redirect back to form page and save attempted data.
if (count($errors) > 0) {
$_SESSION['updatedata'] = $updatedata;
$_SESSION['errors'] = $errors;
header("Location: ../edit.php");
}else{
unset($_SESSION['updatedata']);
unset($_SESSION['errors']);
}
if(isset($_SESSION['errors'])) {
$errors = $_SESSION['errors'];
for ($errorCount = 0; $errorCount < count($errors); $errorCount++) {
echo ("<p class='error'>Error: " . $errors[$errorCount] . "</p>");
}
}
?>
<div id="form">
<h2> Edit Product </h2>
<form action="edit.php?ItemID=<?php echo $productID; ?>" method="POST" >
<fieldset>
<h4>Sell Your Item</h4>
<p><label class="title" for="Name">Name:</label>
<input type="text" placeholder="<?php echo $data['Name']; ?>" name="Name" id="Name" title="Please enter item name"
readonly ><br />
<label class="title" for="Description">Description:</label>
<textarea name="Description" rows="5" cols="33" placeholder="<?php echo $data['Description']; ?>" id="Description" title="Please describe your item" ></textarea><br />
<img src="../img/<?php echo $data['img_path']; ?>" />
<br>
Select image to upload:
<input type="file" name="img_path" placeholder="<?php echo $data['img_path']; ?>" id="img_path" accept="image/jpg"><br>
<label class="title" for="Quantity">Quantity:</label>
<input type="text" placeholder="<?php echo $data['Quantity']; ?>" name="Quantity" id="Quantity" title="Number of items" readonly><br />
<label class="title" for="Category">Category:</label>
<input type="text" placeholder="<?php echo $data['Category']; ?>" name="Category" id="Category" Title="Category" readonly >
<label class="title" for="Location">Location:</label>
<input type="text" placeholder="<?php echo $data['Location']; ?>" name="Location" id="Location" title="Enter item location" ><br />
<label class="title" for="Saletype">Sale Type:</label>
<input type="text" placeholder="<?php echo $data['Saletype']; ?>" name="Saletype" id="Saletype" title="Sale Type" readonly >
<label class="title" for="Price">Price: $</label>
<input type="text" placeholder="<?php echo $data['Price']; ?>" name="Price" id="Price" title="Please enter your name" readonly><br />
<label class="title" for="Duration">Duration:</label>
<input type="text" placeholder="<?php echo $data['Duration']; ?>" name="Duration" id="Duration" title="End Date" readonly><br />
<label class="title" for="Payment">Payment Type:</label>
<input type="text" placeholder="<?php echo $data['Payment']; ?>" name="Payment" id="Payment" title="Payment" readonly >
<select name="Payment" id="Payment" >
<option value="PayPal">PayPal</option>
<option value="Bank Deposit">Bank Deposit</option>
<option value="Card">Credit Card</option>
</select><br>
<div class="submit"><input type="submit" value="submit" name="submit" /></div>
<div class="reset"><input type="reset" /></div>
</fieldset>
</form>

Answer 1

You could use the required attribute on the HTML form. This will ensure the form can not be submitted unless there are input values.
<input type="text" required />
In your PHP file, you can use the isset() function to check all the values.
if (isset($description) && isset($img_path) && isset($description) && isset($payment))
{
// other code
}
You should also make sure to escape the values.
if (isset($description) && isset($img_path) && isset($description) && isset($payment))
{
$description = mysqli_real_escape_string($conn, $description);
$img_path = mysqli_real_escape_string($conn, $img_path);
$location = mysqli_real_escape_string($conn, $location);
$payment = mysqli_real_escape_string($conn, $payment);
$updateQuery = "UPDATE item SET Description = '$Description', img_path = '$img_path', Location = '$Location', Payment = '$Payment' WHERE ItemID= $productID";
$mysqli->query($updateQuery);
}
The mysqli_real_escape_string escapes special characters in a string for use in an SQL statement, taking into account the current charset of the connection
You should always do validation on both frontend and backend.

Answer 2

Try this.. this would work.. It worked for me..
<input type="text" name="name" value="<?php echo $name; ?>" required="required" placeholder="Enter name">