feature:修复创建修改培训材料，文件不能为空

service/learning/material.go

@@ -128,6 +128,9 @@ func (s LearningMaterialService) Add(ctx context.Context, req *learning.Learning
 	if err != nil {
 		return 0, err
 	}
+	if len(req.File) == 0 {
+		return int(id), err
+	}
 
 	files := []learning.LearningMaterialFile{}
 	for _, f := range req.File {
@@ -216,6 +219,10 @@ func (s LearningMaterialService) Update(ctx context.Context, req *learning.Learn
 	if err != nil {
 		return err
 	}
+	if len(req.File) == 0 {
+		return nil
+	}
+
 	files := []learning.LearningMaterialFile{}
 	for _, f := range req.File {
 		files = append(files, learning.LearningMaterialFile{