Validation Patterns

Required Fields

Check whether a required text value is present.

required-field Validation often starts by trimming input and checking that the required value is not empty.

Required Fields

name
required_field.php
Replay: real traced execution (multi-file project)
<?php
$name = "";
$trimmed = trim($name);
$status = $trimmed === "" ? "missing" : "ok";

echo "name=" . $name . "\n";
echo "status=" . $status . "\n";

<?php
$name = "Ada";
$trimmed = trim($name);
$status = $trimmed === "" ? "missing" : "ok";

echo "name=" . $name . "\n";
echo "status=" . $status . "\n";

<?php
$name = "Lin";
$trimmed = trim($name);
$status = $trimmed === "" ? "missing" : "ok";

echo "name=" . $name . "\n";
echo "status=" . $status . "\n";

  1. $name ← (empty), $trimmed ← (empty), $status ← missing

    1<?php2$name→ (empty) = ""; //@name="Ada", "Lin"3$trimmed→ (empty) = trim($name(empty));4$status→ missing = $trimmed(empty) === "" ? "missing" : "ok";56echo "name=" . $name(empty) . "\n";7echo "status=" . $statusmissing . "\n";
    outputname=
status=missing

  1. $name ← Ada, $trimmed ← Ada, $status ← ok

    1<?php2$name→ Ada = "Ada";3$trimmed→ Ada = trim($nameAda);4$status→ ok = $trimmedAda === "" ? "missing" : "ok";56echo "name=" . $nameAda . "\n";7echo "status=" . $statusok . "\n";
    outputname=Ada
status=ok

  1. $name ← Lin, $trimmed ← Lin, $status ← ok

    1<?php2$name→ Lin = "Lin";3$trimmed→ Lin = trim($nameLin);4$status→ ok = $trimmedLin === "" ? "missing" : "ok";56echo "name=" . $nameLin . "\n";7echo "status=" . $statusok . "\n";
    outputname=Lin
status=ok