feat: 商品添加克重字段,订单添加通道费,运费按重量计算

- 商品模型: 添加weight字段(克重)
- 订单模型: 添加channel_fee字段(支付通道费)
- 后台商品管理: 添加克重输入框
- 后台订单详情: 显示通道费
- 订单创建: 根据商品重量计算运费,添加通道费计算
- 购物车: 根据商品重量计算运费,显示通道费

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/internal/api/handlers/order.go

@@ -243,6 +243,7 @@ func (h *OrderHandler) Create(c *gin.Context) {
 
 	var subtotal float64
 	var totalQuantity int
+	var totalWeight float64
 	var orderItems []models.OrderItem
 	supplierMap := make(map[uint]bool)
 
@@ -280,6 +281,7 @@ func (h *OrderHandler) Create(c *gin.Context) {
 
 		subtotal += cart.Product.Price * float64(cart.Quantity)
 		totalQuantity += cart.Quantity
+			totalWeight += cart.Product.Weight * float64(cart.Quantity)
 		orderItems = append(orderItems, models.OrderItem{
 			ProductID: cart.ProductID,
 			Quantity:  cart.Quantity,
@@ -298,7 +300,7 @@ func (h *OrderHandler) Create(c *gin.Context) {
 		break
 	}
 
-	var shippingFeeFirstWeight, shippingFeePerGram, serviceFeeRate, taxRate float64
+	var shippingFeeFirstWeight, shippingFeePerGram, serviceFeeRate, taxRate, channelFeeRate float64
 	var setting models.SystemSetting
 	if err := utils.DB.Where("`key` = ?", "shipping_fee_first_weight").First(&setting).Error; err == nil {
 		shippingFeeFirstWeight, _ = strconv.ParseFloat(setting.Value, 64)
@@ -312,17 +314,23 @@ func (h *OrderHandler) Create(c *gin.Context) {
 	if err := utils.DB.Where("`key` = ?", "tax_rate").First(&setting).Error; err == nil {
 		taxRate, _ = strconv.ParseFloat(setting.Value, 64)
 	}
+	if err := utils.DB.Where("`key` = ?", "payment_channel_fee_rate").First(&setting).Error; err == nil {
+		channelFeeRate, _ = strconv.ParseFloat(setting.Value, 64)
+	}
 
-	shippingFee := shippingFeeFirstWeight
+	// 根据商品重量计算运费
-	if subtotal >= 99 || shippingFeeFirstWeight == 0 {
+	shippingFee := 0.0
-		shippingFee = 0
+	if subtotal < 99 && shippingFeeFirstWeight > 0 {
-	} else if totalQuantity > 500 {
+		shippingFee = shippingFeeFirstWeight
-		shippingFee += shippingFeePerGram * float64(totalQuantity-500)
+		if totalWeight > 500 {
+			shippingFee += shippingFeePerGram * (totalWeight - 500)
+		}
 	}
 
 	serviceFee := subtotal * serviceFeeRate / 100
 	tax := subtotal * taxRate / 100
-	totalAmount := subtotal + shippingFee + serviceFee + tax
+	channelFee := subtotal * channelFeeRate / 100
+	totalAmount := subtotal + shippingFee + serviceFee + tax + channelFee
 
 	order := models.Order{
 		UserID:            userID,
@@ -331,6 +339,7 @@ func (h *OrderHandler) Create(c *gin.Context) {
 		ShippingFee:       shippingFee,
 		ServiceFee:        serviceFee,
 		Tax:               tax,
+		ChannelFee:        channelFee,
 		TotalAmount:       totalAmount,
 		Status:            models.OrderStatusPendingPayment,
 		ShippingAddressID: &req.ShippingAddressID,

backend/internal/models/order.go

@@ -14,6 +14,7 @@ type Order struct {
 	ShippingFee      float64        `gorm:"type:decimal(10,2);default:0" json:"shipping_fee"`
 	ServiceFee       float64        `gorm:"type:decimal(10,2);default:0" json:"service_fee"`
 	Tax              float64        `gorm:"type:decimal(10,2);default:0" json:"tax"`
+	ChannelFee       float64        `gorm:"type:decimal(10,2);default:0" json:"channel_fee"` // 支付通道费
 	TotalAmount      float64        `gorm:"type:decimal(10,2);not null" json:"total_amount"`
 	RefundAmount     *float64       `gorm:"type:decimal(10,2)" json:"refund_amount"`
 	RefundStatus     string         `gorm:"size:20" json:"refund_status"`

backend/internal/models/product.go

@@ -11,6 +11,7 @@ type Product struct {
 	Name          string         `gorm:"size:255;not null" json:"name"`
 	Description   string         `json:"description"`
 	Price         float64        `gorm:"type:decimal(10,2);not null" json:"price"`
+	Weight        float64        `gorm:"type:decimal(10,2);default:0" json:"weight"` // 商品克重（克）
 	MinPurchase   int            `gorm:"default:1" json:"min_purchase"`
 	MaxPurchase   *int           `json:"max_purchase"`
 	MinWeight     *float64       `json:"min_weight"`

frontend/src/views/admin/Orders.vue

@@ -104,6 +104,10 @@
               <span>税费</span>
               <span>¥{{ (currentOrder.tax || 0).toFixed(2) }}</span>
             </div>
+            <div class="fee-item" v-if="currentOrder.channel_fee > 0">
+              <span>通道费</span>
+              <span>¥{{ (currentOrder.channel_fee || 0).toFixed(2) }}</span>
+            </div>
             <div class="fee-item total">
               <span>合计</span>
               <span class="total-amount">¥{{ (currentOrder.total_amount || 0).toFixed(2) }}</span>

frontend/src/views/admin/Products.vue

@@ -80,17 +80,22 @@
         <div class="form-section">
           <div class="section-title">价格库存</div>
           <el-row :gutter="16">
-            <el-col :span="8">
+            <el-col :span="6">
               <el-form-item label="价格" required>
                 <el-input-number v-model="form.price" :precision="2" :min="0" style="width: 100%" />
               </el-form-item>
             </el-col>
-            <el-col :span="8">
+            <el-col :span="6">
               <el-form-item label="库存">
                 <el-input-number v-model="form.stock" :min="0" style="width: 100%" />
               </el-form-item>
             </el-col>
-            <el-col :span="8">
+            <el-col :span="6">
+              <el-form-item label="克重(克)">
+                <el-input-number v-model="form.weight" :precision="1" :min="0" style="width: 100%" />
+              </el-form-item>
+            </el-col>
+            <el-col :span="6">
               <el-form-item label="上架">
                 <el-switch v-model="form.is_active" />
               </el-form-item>
@@ -188,6 +193,7 @@ const form = reactive({
   name: '',
   description: '',
   price: 0,
+  weight: 0,
   stock: 0,
   min_purchase: 1,
   max_purchase: undefined as number | undefined,
@@ -265,7 +271,7 @@ async function fetchBrands() {
 function openAdd() {
   editing.value = null
   Object.assign(form, {
-    name: '', description: '', price: 0, stock: 0, 
+    name: '', description: '', price: 0, weight: 0, stock: 0,
     min_purchase: 1, max_purchase: undefined,
     require_credit: false, credit_cost: 0, credit_reward: 0,
     is_active: true, category_ids: [], brand_id: undefined
@@ -281,6 +287,7 @@ function editProd(row: any) {
     name: row.name,
     description: row.description || '',
     price: row.price,
+    weight: row.weight || 0,
     stock: row.stock || 0,
     min_purchase: row.min_purchase || 1,
     max_purchase: row.max_purchase,

frontend/src/views/user/Cart.vue

@@ -210,6 +210,11 @@
           <span>¥{{ taxFee.toFixed(2) }}</span>
         </div>
 
+        <div class="summary-row" v-if="channelFee > 0">
+          <span>通道费 ({{ settings.payment_channel_fee_rate || 0 }}%)</span>
+          <span>¥{{ channelFee.toFixed(2) }}</span>
+        </div>
+
         <div class="summary-divider"></div>
         
         <div class="summary-row summary-total">
@@ -334,11 +339,18 @@ const selectedQuantity = computed(() => {
     .reduce((sum, item) => sum + item.quantity, 0)
 })
 
+// 计算选中商品的总重量
+const selectedWeight = computed(() => {
+  return items.value
+    .filter(item => selectedIds.value.includes(item.id))
+    .reduce((sum, item) => sum + (item.product?.weight || 0) * item.quantity, 0)
+})
+
 const shippingFee = computed(() => {
   const firstWeight = parseFloat(settings.value.shipping_fee_first_weight || '0')
   const perGram = parseFloat(settings.value.shipping_fee_per_gram || '0')
   if (selectedTotal.value >= 99 || firstWeight === 0) return 0
-  return firstWeight + perGram * Math.max(0, selectedQuantity.value - 500)
+  return firstWeight + perGram * Math.max(0, selectedWeight.value - 500)
 })
 
 const serviceFee = computed(() => {
@@ -351,8 +363,13 @@ const taxFee = computed(() => {
   return selectedTotal.value * rate / 100
 })
 
+const channelFee = computed(() => {
+  const rate = parseFloat(settings.value.payment_channel_fee_rate || '0')
+  return selectedTotal.value * rate / 100
+})
+
 const grandTotal = computed(() => {
-  return selectedTotal.value + shippingFee.value + serviceFee.value + taxFee.value
+  return selectedTotal.value + shippingFee.value + serviceFee.value + taxFee.value + channelFee.value
 })
 
 const canCheckout = computed(() => {