2nd/10_Wiki/Dev/Topic_PHP/PHP_Form_Required.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
php-form-required	PHP Form Required	Programming_Language	draft	conceptual		empty() PHP 필수 필드		B	0.89	2026-07-04	2026-07-04			php programming w3schools forms validation required	https://www.w3schools.com/php/php_form_required.asp

PHP Form Required

🎯 한 줄 통찰 (One-line insight)

The pattern for making a field "required" is a mirrored if/else: empty($_POST["field"]) sets an ERROR message and leaves the display variable untouched, while the else branch runs the field through test_input() — meaning error state and sanitized value live in two separate variables that are only ever set on opposite branches of the same check. [S1]

🧠 핵심 개념 (Core concepts)

• empty($_POST["field"]) — checks if a field was left blank. [S1]
• Error variables — $nameErr, $emailErr, $genderErr, $websiteErr — hold per-field error messages, initialized empty. [S1]
• Required vs. optional handling — required fields set an error message when empty; optional fields just stay empty (no error) when blank. [S1]
• Displaying errors inline — <span class="error"><?php echo $nameErr;?></span> placed next to each field. [S1]

📖 세부 내용 (Details)

• Required field check: if (empty($_POST["name"])) { $nameErr = "Name is required"; } else { $name = test_input($_POST["name"]); }. [S1]
• Optional field (no error): if (empty($_POST["website"])) { $website = ""; } else { $website = test_input($_POST["website"]); }. [S1]
• Inline error display: Name: <input type="text" name="name"> <span class="error">* <?php echo $nameErr;?></span>. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 필수 필드(이름/이메일/성별)와 선택 필드(웹사이트/코멘트)를 다르게 처리하는 것이 실전 폼 검증의 표준 구조다. [S1]

💻 코드 패턴 (Code patterns)

Required-field validation with error message (PHP):

if (empty($_POST["name"])) {
    $nameErr = "Name is required";
} else {
    $name = test_input($_POST["name"]);
}

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.89
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: PHP Tutorial
• 관련 개념: PHP Form Validation, PHP Form URL Email
• 참조 맥락: 필수 필드 검증 — 이메일/URL 형식 검증(URL Email) 챕터로 이어짐.

📚 출처 (Sources)

• [S1] W3Schools — PHP Forms - Required Fields — https://www.w3schools.com/php/php_form_required.asp

📝 변경 이력 (Change history)

• 2026-07-04: Initial draft synthesized from the W3Schools "PHP Forms - Required Fields" page (Astra wiki-curation, P-Reinforce v3.1 format).