四選一填寫驗證

Altob.NtuInvoiceGateway/Pages/Invoice.cshtml

@@ -58,12 +58,12 @@
                         <input type="hidden" asp-for="InvoiceData.TaxType" />
 
                         <div class="alert alert-info mb-4">
-                            <strong>注意：</strong>以下四個選項至少需填寫一個
+                            <strong>注意：</strong>以下四個選項僅能擇一填寫
                         </div>
 
                         <div class="row mb-3">
                             <div class="col-md-6">
-                                <label asp-for="InvoiceData.Email" class="form-label">消費者信箱(寄送發票開立通知用)</label>
+                                <label asp-for="InvoiceData.Email" class="form-label">Email(寄送發票開立通知用)</label>
                                 <input asp-for="InvoiceData.Email" class="form-control" type="email" maxlength="64" placeholder="example@email.com" />
                                 <span asp-validation-for="InvoiceData.Email" class="text-danger"></span>
                             </div>

Altob.NtuInvoiceGateway/Pages/Invoice.cshtml.cs

@@ -216,7 +216,7 @@ public class InvoiceModel : PageModel
             return Page();
         }
 
-        // 驗證 Email, CarrierID, BuyerIdentifier 至少填寫一個
+        // 驗證 Email, CarrierID, BuyerIdentifier, LoveCode 僅能擇一填寫
         int filledCount = 0;
         if (!string.IsNullOrEmpty(InvoiceData.Email)) filledCount++;
         if (!string.IsNullOrEmpty(InvoiceData.CarrierID)) filledCount++;
@@ -225,7 +225,13 @@ public class InvoiceModel : PageModel
 
         if (filledCount == 0)
         {
-            ErrorMessage = "Email、手機條碼、購買者統編至少需填寫一個";
+            ErrorMessage = "Email、手機條碼、購買者統編、捐贈碼僅能擇一填寫，請填寫任一項";
+            return Page();
+        }
+
+        if (filledCount > 1)
+        {
+            ErrorMessage = "Email、手機條碼、購買者統編、捐贈碼僅能擇一填寫，請刪除多餘輸入";
             return Page();
         }