diff --git a/model.go b/model.go
index 5af17bf..ed0be4e 100644
--- a/model.go
+++ b/model.go
@@ -387,7 +387,7 @@ func (m *Model) Search(w http.ResponseWriter, r *http.Request) {
 	childCtx := context.WithValue(r.Context(), RuntimeScopeKey, &types.RuntimeScope{
 		Domain:     domainName,
 		Request:    r,
-		User:       m.valueLookup("user", w, r),
+		User:       m.valueLookup(types.FieldUser, w, r),
 		ModuleName: m.naming.ModuleName,
 		TableName:  m.naming.TableName,
 		Scenario:   types.ScenarioList,
@@ -490,7 +490,7 @@ func (m *Model) Create(w http.ResponseWriter, r *http.Request) {
 	diffAttrs = make([]*types.DiffAttr, 0, 10)
 	childCtx := context.WithValue(r.Context(), RuntimeScopeKey, &types.RuntimeScope{
 		Domain:     domainName,
-		User:       m.valueLookup("user", w, r),
+		User:       m.valueLookup(types.FieldUser, w, r),
 		Request:    r,
 		ModuleName: m.naming.ModuleName,
 		TableName:  m.naming.TableName,
@@ -588,7 +588,7 @@ func (m *Model) Update(w http.ResponseWriter, r *http.Request) {
 	childCtx := context.WithValue(r.Context(), RuntimeScopeKey, &types.RuntimeScope{
 		Domain:          domainName,
 		Request:         r,
-		User:            m.valueLookup("user", w, r),
+		User:            m.valueLookup(types.FieldUser, w, r),
 		ModuleName:      m.naming.ModuleName,
 		TableName:       m.naming.TableName,
 		Scenario:        types.ScenarioUpdate,
@@ -671,7 +671,7 @@ func (m *Model) Delete(w http.ResponseWriter, r *http.Request) {
 	}
 	childCtx := context.WithValue(r.Context(), RuntimeScopeKey, &types.RuntimeScope{
 		Domain:          m.valueLookup(types.FieldDomain, w, r),
-		User:            m.valueLookup("user", w, r),
+		User:            m.valueLookup(types.FieldUser, w, r),
 		Request:         r,
 		ModuleName:      m.naming.ModuleName,
 		TableName:       m.naming.TableName,
@@ -790,7 +790,7 @@ func (m *Model) Export(w http.ResponseWriter, r *http.Request) {
 	childCtx := context.WithValue(r.Context(), RuntimeScopeKey, &types.RuntimeScope{
 		Domain:     domainName,
 		Request:    r,
-		User:       m.valueLookup("user", w, r),
+		User:       m.valueLookup(types.FieldUser, w, r),
 		ModuleName: m.naming.ModuleName,
 		TableName:  m.naming.TableName,
 		Scenario:   types.ScenarioExport,
@@ -988,7 +988,7 @@ __end:
 	if result.TotalCount > result.SuccessCount {
 		result.FailureFile = failureFile
 	}
-	result.Duration = time.Now().Sub(tm)
+	result.Duration = time.Since(tm)
 	m.getHook().afterImport(ctx, result)
 }
 
@@ -1022,7 +1022,7 @@ func (m *Model) Import(w http.ResponseWriter, r *http.Request) {
 	//这里用background的context
 	childCtx := context.WithValue(context.Background(), RuntimeScopeKey, &types.RuntimeScope{
 		Domain:     domainName,
-		User:       m.valueLookup("user", w, r),
+		User:       m.valueLookup(types.FieldUser, w, r),
 		ModuleName: m.naming.ModuleName,
 		TableName:  m.naming.TableName,
 		Scenario:   types.ScenarioImport,
@@ -1075,7 +1075,7 @@ func (m *Model) Import(w http.ResponseWriter, r *http.Request) {
 	fast, _ = strconv.ParseBool(qs.Get("__fast"))
 	go m.importInternal(childCtx, domainName, schemas, filename, fast, extraFields)
 	m.response.Success(w, types.ImportResponse{
-		UID:    m.valueLookup("user", w, r),
+		UID:    m.valueLookup(types.FieldUser, w, r),
 		Status: "committed",
 	})
 }
@@ -1096,7 +1096,7 @@ func newModel(v any, db *gorm.DB, naming types.Naming) *Model {
 		Clauses:  map[string]clause.Clause{},
 	}
 	if err := model.statement.Parse(v); err == nil {
-		if model.statement.Schema.PrimaryFieldDBNames != nil && len(model.statement.Schema.PrimaryFieldDBNames) > 0 {
+		if model.statement != nil && model.statement.Schema != nil && len(model.statement.Schema.PrimaryFieldDBNames) > 0 {
 			model.primaryKey = model.statement.Schema.PrimaryFieldDBNames[0]
 		}
 	}
diff --git a/types/types.go b/types/types.go
index 605cfdc..a2bf95e 100644
--- a/types/types.go
+++ b/types/types.go
@@ -93,6 +93,7 @@ const (
 )
 
 const (
+	FieldUser   = "user"
 	FieldDomain = "domain"
 )