Flask（Part.69）｜ 【割引機能の利用（一括適用）】

@register_bp.route("/bill/<int:bill_id>/apply_bulk_discount", methods=["POST"])
@login_required
def apply_bulk_discount(bill_id):
    discount_id = request.form.get("discount_id")
    if not discount_id:
        flash("割引が選択されていません。", "warning")
        return redirect(url_for("register.view_bill", bill_id=bill_id))

    discount = Discount.query.get(discount_id)
    if not discount:
        flash("割引が見つかりません。", "danger")
        return redirect(url_for("register.view_bill", bill_id=bill_id))

    orders = Order.query.filter_by(bill_id=bill_id).all()
    for order in orders:
        order.discount_id = discount.id
        order.discount_number = discount.number

    db.session.commit()
    flash("すべての注文に割引を適用しました。", "success")
    return redirect(url_for("register.view_bill", bill_id=bill_id))

<!-- 一括割引フォーム -->
{% if bill.status != 'paid' %}
<form action="{{ url_for('register.apply_bulk_discount', bill_id=bill.id) }}" method="post" style="margin-bottom: 1em;">
    <label for="bulk_discount_id">一括割引:</label>
    <select name="discount_id" id="bulk_discount_id" class="custom-select">
        {% if discount_list %}
        {% for discount in discount_list %}
        <option value="{{ discount.id }}">{{ discount.number }}%{% if discount.priority %}（優先）{% endif %}</option>
        {% endfor %}
        {% endif %}
    </select>
    <button type="submit" class="update-button">適用</button>
</form>