Why Does `isset($_POST)` Always Return True for Empty Forms?

Unveiling the Mystery: Why "isset($_POST)" Always Returns True, Even with Empty Forms

When dealing with form submissions, it's common to rely on the isset() function to check if specific field values have been provided. However, you may encounter a puzzling situation where isset($_POST["field_name"]) always evaluates to true, even if the corresponding field in the submitted form was left blank.

Tracing the Conundrum: Understanding Form Input Behavior

The culprit lies in the nature of form inputs. By default, most form inputs are always considered "set," regardless of whether the user has provided any value. This is because they are automatically populated with empty string values.

The Missing Piece: Incorporating Emptiness Check

To address this issue, you must supplement the isset() check with an emptiness check. One way to achieve this is by using the empty() function.

Rewriting the Code with an Emptiness Check:

if (!empty($_POST["mail"])) {
    echo "Yes, mail is set";    
} else {  
    echo "No, mail is not set";
}

Explanation:

• The !empty() function evaluates to true only if the value of $_POST["mail"] is not empty.
• This ensures that the "Yes, mail is set" message is displayed only if the user has provided a value for the mail field.
• The "No, mail is not set" message is displayed when the field is left blank.

Conclusion:

By incorporating an emptiness check into your code, you can accurately determine whether a form field has been provided a value, resolving the issue of "isset($_POST)" always returning true for empty fields.

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