Php function required field

The Ultimate Guide to PHP Form Validation: Required Fields

A well-designed form is a crucial part of any website or application. Forms are used to gather user data, and they are an essential tool for business and e-commerce websites. Unfortunately, forms can also be the source of numerous problems. For example, a user may forget to fill in a required field, causing the form to fail validation and return an error message. To avoid these problems, it is important to implement proper form validation.

In this article, we will explore the concept of PHP form validation and how to ensure that required fields are filled out correctly. We will cover the following topics:

1. Understanding the PHP form validation process
2. The importance of required fields
3. Implementing the required attribute in PHP
4. Validating required fields with PHP
5. Enhancing form validation with regular expressions

1. Understanding the PHP Form Validation Process

The PHP form validation process is a series of checks that are performed on form data before it is submitted to the server. The purpose of these checks is to ensure that the data entered by the user is complete, accurate, and in the proper format. Form validation is typically performed on the client-side using JavaScript, but it can also be performed on the server-side using PHP.

2. The Importance of Required Fields

Required fields are an essential part of any form. They ensure that important information is collected from the user and prevent the form from being submitted with missing data. For example, in a contact form, the name, email, and message fields are typically required.

3. Implementing the Required Attribute in PHP

The required attribute can be added to a form field to indicate that it is a required field. The attribute is added to the input tag as follows:

input type="text" name="name" required>

4. Validating Required Fields with PHP

To validate required fields with PHP, we will use the isset function. The isset function checks if a variable is set and is not NULL . If the variable is not set, an error message will be displayed.

Here is an example of how to validate a required field in PHP:

if (!isset($_POST['name']) || $_POST['name'] == '') < $errors[] = 'Name is a required field'; >

5. Enhancing Form Validation with Regular Expressions

Regular expressions can be used to enhance form validation by specifying a pattern that the data must match. For example, a regular expression can be used to validate an email address or a phone number.

Here is an example of how to use a regular expression to validate an email address:

if (!preg_match("/^[a-zA-Z0-9._-][email protected][a-zA-Z0-9-]+\.[a-zA-Z.]$/", $_POST['email'])) < $errors[] = 'Email is not in a valid format'; >

In conclusion, form validation is an essential part of any website or application. By implementing the required attribute and validating form data with PHP, you can ensure that important information is collected from the user and prevent the form from being submitted with missing data. Regular expressions can also be used to enhance form validation and ensure that data is in the proper format.

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PHP Forms — Required Fields

This chapter shows how to make input fields required and create error messages if needed.

PHP — Required Fields

From the validation rules table on the previous page, we see that the «Name», «E-mail», and «Gender» fields are required. These fields cannot be empty and must be filled out in the HTML form.

Field	Validation Rules
Name	Required. + Must only contain letters and whitespace
E-mail	Required. + Must contain a valid email address (with @ and .)
Website	Optional. If present, it must contain a valid URL
Comment	Optional. Multi-line input field (textarea)
Gender	Required. Must select one

In the previous chapter, all input fields were optional.

In the following code we have added some new variables: $nameErr, $emailErr, $genderErr, and $websiteErr. These error variables will hold error messages for the required fields. We have also added an if else statement for each $_POST variable. This checks if the $_POST variable is empty (with the PHP empty() function). If it is empty, an error message is stored in the different error variables, and if it is not empty, it sends the user input data through the test_input() function:

// define variables and set to empty values
$nameErr = $emailErr = $genderErr = $websiteErr = «»;
$name = $email = $gender = $comment = $website = «»;

if ($_SERVER[«REQUEST_METHOD»] == «POST») if (empty($_POST[«name»])) $nameErr = «Name is required»;
> else $name = test_input($_POST[«name»]);
>

if (empty($_POST[«email»])) $emailErr = «Email is required»;
> else $email = test_input($_POST[«email»]);
>

if (empty($_POST[«website»])) $website = «»;
> else $website = test_input($_POST[«website»]);
>

if (empty($_POST[«comment»])) $comment = «»;
> else $comment = test_input($_POST[«comment»]);
>

if (empty($_POST[«gender»])) $genderErr = «Gender is required»;
> else $gender = test_input($_POST[«gender»]);
>
>
?>

PHP — Display The Error Messages

Then in the HTML form, we add a little script after each required field, which generates the correct error message if needed (that is if the user tries to submit the form without filling out the required fields):

Example

The next step is to validate the input data, that is «Does the Name field contain only letters and whitespace?», and «Does the E-mail field contain a valid e-mail address syntax?», and if filled out, «Does the Website field contain a valid URL?».

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PHP Required Field: Make Forms with Required Fields

We first mentioned PHP required fields when discussing PHP forms. It means that some of the input fields in a form must be filled if users wish to proceed with the form submission process.

A little asterisk (*) is commonly used to mark the required fields. For example, if you are registering to a new online shopping website, you might have to provide your address so the ordered goods would come to you.

In this tutorial, we will explain how to set required input fields instead of optional ones. It will help you manage the data that users input during registration or commenting. PHP required fields might also be programmed to display error messages when left empty.

Contents

PHP Required Field: Main Tips

• Using PHP forms you can set certain fields to be required and display error messages if they aren’t filled in upon submission.
• This is essential when making any form for actual use with databases and validation.

Example of a Form

Here’s a list of fields we are going to use in our example form:

• Fullname: required, must only contain letters and spaces.
• Email: also required, must be properly formatted.
• Website: optional. If present, must be properly formatted.
• Feedback: optional, the text area allows to enter multiple lines.
• Gender: required, one of the options must be selected.

In the following code we have a few specific variables. We will use them to display errors in case required fields are left empty: $name_error , $email_error , $gender_error , and $website_error .

This can be achieved by using if else conditionals for every $_POST variable. These statements PHP check if variable is empty using the empty() function. In case it is, we store an error message inside the error variable.

Assuming the PHP required fields are all filled in as intended, we continue with our proc_input() function to validate the input:

 $fullname_error = $email_error = $gender_error = $website_error = ""; $fullname = $email = $gender = $feedback = $website = ""; if ($_SERVER["REQUEST_METHOD"] == "POST") < if (empty($_POST["fullname"])) < $fullname_error = "Required"; > else < $fullname = proc_input($_POST["fullname"]); > if (empty($_POST["email"])) < $email_error = "Required"; > else < $email = proc_input($_POST["email"]); > if (empty($_POST["website"])) < $website = ""; > else < $website = proc_input($_POST["website"]); > if (empty($_POST["feedback"])) < $feedback = ""; > else < $feedback = proc_input($_POST["feedback"]); > if (empty($_POST["gender"])) < $gender_error = "Required"; > else < $gender = proc_input($_POST["gender"]); > > ?>

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Displaying Error Messages

Finally, we add a bit of code next to each of the PHP required field in the HTML code. It is meant to display the error messages we have set up:

form method="post" action="PHP_SELF"]);?>"> input type="text" name="fullname" placeholder="Full name"> span>* echo $fullname_error;?> span>br> input type="text" name="email" placeholder="E-mail"> span>* echo $email_error;?> span>br> input type="text" name="website" placeholder="Website URL"> span> echo $website_error;?> span>br> textarea name="feedback" rows="6" cols="50" placeholder="Feedback"> textarea>br>br> input type="radio" name="gender" value="f">F input type="radio" name="gender" value="m">M span>* echo $gender_error;?> span>br>br> input type="submit" name="submit" value="Submit"> form>

PHP Required Field: Summary

• If you set certain fields in the forms as required and they are left empty, an error message will be outputted.
• Required fields ensure you get all the data you need from users during registration (or other process).

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PHP Form Required Fields

This chapter explains how to make input fields required and, if necessary, provide error messages.

PHP Form Required Fields

Let’s look at a PHP for fields, some of which cannot be left blank and must be filled out:

Field	Validation Rules
Name	Required+ It can only contain letters and whitespaces.
E-mail	Required. + Must contain a valid email address (with @ and .)
Gender	Required + Must select from the given option.
Comment	Optional – Multiple line text.

Now, let’s look at an example to see how we can make the above fields mandatory, and then we’ll talk about how the code works.

 else < $name = test_input($_POST["name"]); >if (empty($_POST["email"])) < $emailError = "Email is required"; >else < $email = test_input($_POST["email"]); >if (empty($_POST["gender"])) < $genderError = "Gender is required"; >else < $gender = test_input($_POST["gender"]); >if (empty($_POST["comment"])) < $comment = ""; >else < $comment = test_input($_POST["comment"]); >> ?>

We’ve added several additional variables to the above code: $nameError, $emailError, and $genderError. The required fields error messages will be stored in these error variables. For each $_POST variable, we’ve added an if else expression. This uses the PHP empty() method to see if the $_POST variable is empty.

If the required field empty, an error message is saved in the various error variables; if it’s not empty, the test_input() function gives the user input data:

Let’s take a look at how we may display these error messages that we defined earlier:

PHP – Display The Error Messages

Then, we put a script after each required field in the HTML form that generates the proper error message if the user tries to submit the form without filling out all required data.

Example

    .error  else < $name = test_input($_POST["name"]); >if (empty($_POST["email"])) < $emailError = "Email is required"; >else < $email = test_input($_POST["email"]); >if (empty($_POST["gender"])) < $genderError = "Gender is required"; >else < $gender = test_input($_POST["gender"]); >if (empty($_POST["comment"])) < $comment = ""; >else < $comment = test_input($_POST["comment"]); >> function test_input($data) < $data = trim($data); $data = stripslashes($data); $data = htmlspecialchars($data); return $data; >?> 
PHP Form Validation Example
 
* required field
 "> Name: * 
 
E-mail: * 
 
Gender: Female Male Other * 
 
Comment: 
 
Your Input:"; echo $name; echo "
"; echo $email; echo "
"; echo $gender; echo "
"; echo $comment; ?> 

This is how the required fields will look like:

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