diff --git a/controller/charge.go b/controller/charge.go
index 9aee3f6..cb33120 100644
--- a/controller/charge.go
+++ b/controller/charge.go
@@ -2,7 +2,6 @@ package controller
 
 import (
 	"electricity_bill_calc/model"
-	"electricity_bill_calc/repository"
 	"electricity_bill_calc/response"
 	"electricity_bill_calc/security"
 	"electricity_bill_calc/service"
@@ -40,7 +39,7 @@ func listAllCharges(c *gin.Context) {
 	requestKeyword := c.DefaultQuery("keyword", "")
 	requestBeginDate := c.DefaultQuery("begin", "")
 	requestEndDate := c.DefaultQuery("end", "")
-	charges, total, err := repository.ChargeRepo.ListPagedChargeRecord(requestKeyword, requestBeginDate, requestEndDate, requestPage)
+	charges, total, err := service.ChargeService.ListPagedChargeRecord(requestKeyword, requestBeginDate, requestEndDate, requestPage)
 	if err != nil {
 		result.NotFound(err.Error())
 		return
diff --git a/repository/charge.go b/repository/charge.go
deleted file mode 100644
index e36bd36..0000000
--- a/repository/charge.go
+++ /dev/null
@@ -1,82 +0,0 @@
-package repository
-
-import (
-	"electricity_bill_calc/config"
-	"electricity_bill_calc/global"
-	"electricity_bill_calc/model"
-	"electricity_bill_calc/utils"
-	"time"
-
-	"xorm.io/builder"
-)
-
-type _ChargeRepository struct{}
-
-var ChargeRepo _ChargeRepository
-
-func (_ChargeRepository) ListPagedChargeRecord(keyword, beginDate, endDate string, page int) ([]model.ChargeWithName, int64, error) {
-	var cond = builder.NewCond()
-	if len(keyword) != 0 {
-		cond = cond.And(builder.Like{"d.name", keyword}.Or(builder.Like{"d.abbr", keyword}))
-	}
-	if len(beginDate) != 0 {
-		beginTime, err := time.ParseInLocation("2006-01-02", beginDate, time.Local)
-		beginTime = utils.VeryBeginOfDate(beginTime)
-		if err != nil {
-			return make([]model.ChargeWithName, 0), 0, err
-		}
-		cond = cond.And(builder.Gte{"c.created_at": beginTime})
-	}
-	if len(endDate) != 0 {
-		endTime, err := time.ParseInLocation("2006-01-02", endDate, time.Local)
-		endTime = utils.VeryEndOfDate(endTime)
-		if err != nil {
-			return make([]model.ChargeWithName, 0), 0, err
-		}
-		cond = cond.And(builder.Lte{"c.created_at": endTime})
-	}
-	startItem := (page - 1) * config.ServiceSettings.ItemsPageSize
-	total, err := global.DBConn.
-		Alias("d").
-		Join("INNER", []string{"user_charge", "c"}, "c.user_id=d.id").
-		Where(cond).
-		NoAutoCondition().
-		Count(&model.ChargeWithName{})
-	if err != nil {
-		return nil, -1, err
-	}
-	charges := make([]model.ChargeWithName, 0)
-	err = global.DBConn.
-		Alias("d").
-		Join("INNER", []string{"user_charge", "c"}, "c.user_id=d.id").
-		Where(cond).
-		Limit(config.ServiceSettings.ItemsPageSize, startItem).
-		NoAutoCondition().
-		Find(&charges)
-	return charges, total, err
-}
-
-func (_ChargeRepository) LastValidChargeTo(uid string) (time.Time, error) {
-	veryBlankTime, _ := time.Parse("2006-01-02 15:04:05", "0001-01-01 00:00:00")
-	var records []string
-	err := global.DBConn.
-		Table(&model.UserCharge{}).
-		Where(builder.Eq{"settled": true, "cancelled": false, "refunded": false, "user_id": uid}).
-		Cols("charge_to").
-		Find(&records)
-	if err != nil {
-		return veryBlankTime, nil
-	}
-	mappedRecords := utils.Map(records, func(elem string) time.Time {
-		t, _ := time.Parse(time.RFC3339, elem)
-		return utils.VeryBeginOfDate(t)
-	})
-	lastValid := utils.Reduce(mappedRecords, veryBlankTime, func(acc, elem time.Time) time.Time {
-		if elem.After(acc) {
-			return elem
-		} else {
-			return acc
-		}
-	})
-	return lastValid, nil
-}
diff --git a/service/abstract.go b/service/abstract.go
new file mode 100644
index 0000000..59ab737
--- /dev/null
+++ b/service/abstract.go
@@ -0,0 +1,23 @@
+package service
+
+func _postProcessSingle[T interface{}](instance *T, has bool, err error) (*T, error) {
+	if err != nil {
+		return nil, err
+	}
+	if has {
+		return instance, nil
+	} else {
+		return nil, nil
+	}
+}
+
+func _postProcessList[T interface{}](instance []*T, has bool, err error) ([]*T, error) {
+	if err != nil {
+		return nil, err
+	}
+	if has {
+		return instance, nil
+	} else {
+		return nil, nil
+	}
+}
diff --git a/service/charge.go b/service/charge.go
index c1e3164..809d67a 100644
--- a/service/charge.go
+++ b/service/charge.go
@@ -1,10 +1,11 @@
 package service
 
 import (
+	"electricity_bill_calc/config"
 	"electricity_bill_calc/exceptions"
 	"electricity_bill_calc/global"
 	"electricity_bill_calc/model"
-	"electricity_bill_calc/repository"
+	"electricity_bill_calc/utils"
 	"time"
 
 	"xorm.io/builder"
@@ -101,7 +102,7 @@ func (c _ChargeService) RefundCharge(seq int64, uid string) error {
 		tx.Rollback()
 		return exceptions.NewNotFoundError("未找到匹配指定条件的计费记录。")
 	}
-	lastValidExpriation, err := repository.ChargeRepo.LastValidChargeTo(uid)
+	lastValidExpriation, err := c.lastValidChargeTo(uid)
 	if err != nil {
 		tx.Rollback()
 		return exceptions.NewNotFoundError("未找到最后合法的计费时间。")
@@ -144,7 +145,7 @@ func (c _ChargeService) CancelCharge(seq int64, uid string) error {
 	if err := tx.Begin(); err != nil {
 		return err
 	}
-	lastValidExpriation, err := repository.ChargeRepo.LastValidChargeTo(uid)
+	lastValidExpriation, err := c.lastValidChargeTo(uid)
 	if err != nil {
 		return exceptions.NewNotFoundError("未找到最后合法的计费时间。")
 	}
@@ -167,3 +168,70 @@ func (_ChargeService) updateUserExpiration(tx *xorm.Session, uid string, expirat
 	}
 	return err
 }
+
+func (_ChargeService) ListPagedChargeRecord(keyword, beginDate, endDate string, page int) ([]model.ChargeWithName, int64, error) {
+	var cond = builder.NewCond()
+	if len(keyword) != 0 {
+		cond = cond.And(builder.Like{"d.name", keyword}.Or(builder.Like{"d.abbr", keyword}))
+	}
+	if len(beginDate) != 0 {
+		beginTime, err := time.ParseInLocation("2006-01-02", beginDate, time.Local)
+		beginTime = utils.VeryBeginOfDate(beginTime)
+		if err != nil {
+			return make([]model.ChargeWithName, 0), 0, err
+		}
+		cond = cond.And(builder.Gte{"c.created_at": beginTime})
+	}
+	if len(endDate) != 0 {
+		endTime, err := time.ParseInLocation("2006-01-02", endDate, time.Local)
+		endTime = utils.VeryEndOfDate(endTime)
+		if err != nil {
+			return make([]model.ChargeWithName, 0), 0, err
+		}
+		cond = cond.And(builder.Lte{"c.created_at": endTime})
+	}
+	startItem := (page - 1) * config.ServiceSettings.ItemsPageSize
+	total, err := global.DBConn.
+		Alias("d").
+		Join("INNER", []string{"user_charge", "c"}, "c.user_id=d.id").
+		Where(cond).
+		NoAutoCondition().
+		Count(&model.ChargeWithName{})
+	if err != nil {
+		return nil, -1, err
+	}
+	charges := make([]model.ChargeWithName, 0)
+	err = global.DBConn.
+		Alias("d").
+		Join("INNER", []string{"user_charge", "c"}, "c.user_id=d.id").
+		Where(cond).
+		Limit(config.ServiceSettings.ItemsPageSize, startItem).
+		NoAutoCondition().
+		Find(&charges)
+	return charges, total, err
+}
+
+func (_ChargeService) lastValidChargeTo(uid string) (time.Time, error) {
+	veryBlankTime, _ := time.Parse("2006-01-02 15:04:05", "0001-01-01 00:00:00")
+	var records []string
+	err := global.DBConn.
+		Table(&model.UserCharge{}).
+		Where(builder.Eq{"settled": true, "cancelled": false, "refunded": false, "user_id": uid}).
+		Cols("charge_to").
+		Find(&records)
+	if err != nil {
+		return veryBlankTime, nil
+	}
+	mappedRecords := utils.Map(records, func(elem string) time.Time {
+		t, _ := time.Parse(time.RFC3339, elem)
+		return utils.VeryBeginOfDate(t)
+	})
+	lastValid := utils.Reduce(mappedRecords, veryBlankTime, func(acc, elem time.Time) time.Time {
+		if elem.After(acc) {
+			return elem
+		} else {
+			return acc
+		}
+	})
+	return lastValid, nil
+}