fix: admin handlers 添加 DTO 转换修复 JSON 序列化

修复 PR #36 合并后部分 admin handler 直接返回 service 层对象导致
JSON 字段名为 PascalCase 而非期望的 snake_case 问题。

修复内容:
- account_handler: Refresh 接口添加 dto.AccountFromService
- openai_oauth_handler: RefreshAccountToken/CreateAccountFromOAuth 添加 dto 转换
- subscription_handler: BulkAssign 添加 dto.BulkAssignResultFromService
- usage_handler: List 接口添加 dto.UsageLogFromService 转换
- 新增 dto.BulkAssignResult 类型和对应的 mapper 函数

backend/internal/handler/admin/account_handler.go

@@ -376,7 +376,7 @@ func (h *AccountHandler) Refresh(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, updatedAccount)
+	response.Success(c, dto.AccountFromService(updatedAccount))
 }
 
 // GetStats handles getting account statistics

backend/internal/handler/admin/openai_oauth_handler.go

@@ -3,6 +3,7 @@ package admin
 import (
 	"strconv"
 
+	"github.com/Wei-Shaw/sub2api/internal/handler/dto"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 
@@ -163,7 +164,7 @@ func (h *OpenAIOAuthHandler) RefreshAccountToken(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, updatedAccount)
+	response.Success(c, dto.AccountFromService(updatedAccount))
 }
 
 // CreateAccountFromOAuth creates a new OpenAI OAuth account from token info
@@ -224,5 +225,5 @@ func (h *OpenAIOAuthHandler) CreateAccountFromOAuth(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, account)
+	response.Success(c, dto.AccountFromService(account))
 }

backend/internal/handler/admin/proxy_handler.go

@@ -4,6 +4,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/Wei-Shaw/sub2api/internal/handler/dto"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 
@@ -57,7 +58,11 @@ func (h *ProxyHandler) List(c *gin.Context) {
 		return
 	}
 
-	response.Paginated(c, proxies, total, page, pageSize)
+	out := make([]dto.Proxy, 0, len(proxies))
+	for i := range proxies {
+		out = append(out, *dto.ProxyFromService(&proxies[i]))
+	}
+	response.Paginated(c, out, total, page, pageSize)
 }
 
 // GetAll handles getting all active proxies without pagination
@@ -72,7 +77,11 @@ func (h *ProxyHandler) GetAll(c *gin.Context) {
 			response.ErrorFrom(c, err)
 			return
 		}
-		response.Success(c, proxies)
+		out := make([]dto.ProxyWithAccountCount, 0, len(proxies))
+		for i := range proxies {
+			out = append(out, *dto.ProxyWithAccountCountFromService(&proxies[i]))
+		}
+		response.Success(c, out)
 		return
 	}
 
@@ -82,7 +91,11 @@ func (h *ProxyHandler) GetAll(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, proxies)
+	out := make([]dto.Proxy, 0, len(proxies))
+	for i := range proxies {
+		out = append(out, *dto.ProxyFromService(&proxies[i]))
+	}
+	response.Success(c, out)
 }
 
 // GetByID handles getting a proxy by ID
@@ -100,7 +113,7 @@ func (h *ProxyHandler) GetByID(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, proxy)
+	response.Success(c, dto.ProxyFromService(proxy))
 }
 
 // Create handles creating a new proxy
@@ -125,7 +138,7 @@ func (h *ProxyHandler) Create(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, proxy)
+	response.Success(c, dto.ProxyFromService(proxy))
 }
 
 // Update handles updating a proxy
@@ -157,7 +170,7 @@ func (h *ProxyHandler) Update(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, proxy)
+	response.Success(c, dto.ProxyFromService(proxy))
 }
 
 // Delete handles deleting a proxy
@@ -233,7 +246,11 @@ func (h *ProxyHandler) GetProxyAccounts(c *gin.Context) {
 		return
 	}
 
-	response.Paginated(c, accounts, total, page, pageSize)
+	out := make([]dto.Account, 0, len(accounts))
+	for i := range accounts {
+		out = append(out, *dto.AccountFromService(&accounts[i]))
+	}
+	response.Paginated(c, out, total, page, pageSize)
 }
 
 // BatchCreateProxyItem represents a single proxy in batch create request

backend/internal/handler/admin/redeem_handler.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"strconv"
 
+	"github.com/Wei-Shaw/sub2api/internal/handler/dto"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 
@@ -47,7 +48,11 @@ func (h *RedeemHandler) List(c *gin.Context) {
 		return
 	}
 
-	response.Paginated(c, codes, total, page, pageSize)
+	out := make([]dto.RedeemCode, 0, len(codes))
+	for i := range codes {
+		out = append(out, *dto.RedeemCodeFromService(&codes[i]))
+	}
+	response.Paginated(c, out, total, page, pageSize)
 }
 
 // GetByID handles getting a redeem code by ID
@@ -65,7 +70,7 @@ func (h *RedeemHandler) GetByID(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, code)
+	response.Success(c, dto.RedeemCodeFromService(code))
 }
 
 // Generate handles generating new redeem codes
@@ -89,7 +94,11 @@ func (h *RedeemHandler) Generate(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, codes)
+	out := make([]dto.RedeemCode, 0, len(codes))
+	for i := range codes {
+		out = append(out, *dto.RedeemCodeFromService(&codes[i]))
+	}
+	response.Success(c, out)
 }
 
 // Delete handles deleting a redeem code
@@ -148,7 +157,7 @@ func (h *RedeemHandler) Expire(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, code)
+	response.Success(c, dto.RedeemCodeFromService(code))
 }
 
 // GetStats handles getting redeem code statistics

backend/internal/handler/admin/subscription_handler.go

@@ -177,7 +177,7 @@ func (h *SubscriptionHandler) BulkAssign(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, result)
+	response.Success(c, dto.BulkAssignResultFromService(result))
 }
 
 // Extend handles extending a subscription

backend/internal/handler/admin/usage_handler.go

@@ -4,6 +4,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/Wei-Shaw/sub2api/internal/handler/dto"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/pagination"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/timezone"
@@ -94,7 +95,11 @@ func (h *UsageHandler) List(c *gin.Context) {
 		return
 	}
 
-	response.Paginated(c, records, result.Total, page, pageSize)
+	out := make([]dto.UsageLog, 0, len(records))
+	for i := range records {
+		out = append(out, *dto.UsageLogFromService(&records[i]))
+	}
+	response.Paginated(c, out, result.Total, page, pageSize)
 }
 
 // Stats handles getting usage statistics with filters

backend/internal/handler/admin/user_handler.go

@@ -3,6 +3,7 @@ package admin
 import (
 	"strconv"
 
+	"github.com/Wei-Shaw/sub2api/internal/handler/dto"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 
@@ -68,7 +69,11 @@ func (h *UserHandler) List(c *gin.Context) {
 		return
 	}
 
-	response.Paginated(c, users, total, page, pageSize)
+	out := make([]dto.User, 0, len(users))
+	for i := range users {
+		out = append(out, *dto.UserFromService(&users[i]))
+	}
+	response.Paginated(c, out, total, page, pageSize)
 }
 
 // GetByID handles getting a user by ID
@@ -86,7 +91,7 @@ func (h *UserHandler) GetByID(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, user)
+	response.Success(c, dto.UserFromService(user))
 }
 
 // Create handles creating a new user
@@ -113,7 +118,7 @@ func (h *UserHandler) Create(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, user)
+	response.Success(c, dto.UserFromService(user))
 }
 
 // Update handles updating a user
@@ -148,7 +153,7 @@ func (h *UserHandler) Update(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, user)
+	response.Success(c, dto.UserFromService(user))
 }
 
 // Delete handles deleting a user
@@ -190,7 +195,7 @@ func (h *UserHandler) UpdateBalance(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, user)
+	response.Success(c, dto.UserFromService(user))
 }
 
 // GetUserAPIKeys handles getting user's API keys
@@ -210,7 +215,11 @@ func (h *UserHandler) GetUserAPIKeys(c *gin.Context) {
 		return
 	}
 
-	response.Paginated(c, keys, total, page, pageSize)
+	out := make([]dto.ApiKey, 0, len(keys))
+	for i := range keys {
+		out = append(out, *dto.ApiKeyFromService(&keys[i]))
+	}
+	response.Paginated(c, out, total, page, pageSize)
 }
 
 // GetUserUsage handles getting user's usage statistics

backend/internal/handler/dto/mappers.go

@@ -292,3 +292,19 @@ func UserSubscriptionFromService(sub *service.UserSubscription) *UserSubscriptio
 		AssignedByUser:     UserFromServiceShallow(sub.AssignedByUser),
 	}
 }
+
+func BulkAssignResultFromService(r *service.BulkAssignResult) *BulkAssignResult {
+	if r == nil {
+		return nil
+	}
+	subs := make([]UserSubscription, 0, len(r.Subscriptions))
+	for i := range r.Subscriptions {
+		subs = append(subs, *UserSubscriptionFromService(&r.Subscriptions[i]))
+	}
+	return &BulkAssignResult{
+		SuccessCount:  r.SuccessCount,
+		FailedCount:   r.FailedCount,
+		Subscriptions: subs,
+		Errors:        r.Errors,
+	}
+}

backend/internal/handler/dto/types.go

@@ -210,3 +210,10 @@ type UserSubscription struct {
 	Group          *Group `json:"group,omitempty"`
 	AssignedByUser *User  `json:"assigned_by_user,omitempty"`
 }
+
+type BulkAssignResult struct {
+	SuccessCount  int                `json:"success_count"`
+	FailedCount   int                `json:"failed_count"`
+	Subscriptions []UserSubscription `json:"subscriptions"`
+	Errors        []string           `json:"errors"`
+}