refactor(backend): update file info retrieval to use models package and improve file slice creation logic

backend/internal/models/file.go

@@ -1,5 +1,11 @@
 package models
 
+import (
+	"backend/internal/utils"
+	"encoding/json"
+	"errors"
+)
+
 type FileInfo struct {
 	FileSize int64  `json:"size"`
 	MimeType string `json:"mime_type"`
@@ -26,3 +32,17 @@ type RedisShareInfo struct {
 	FileId    string `json:"fileId"`
 	CreatedAt int64  `json:"created_at"`
 }
+
+func GetRedisFileInfo(fileId string) (RedisFileInfo, error) {
+	rdb, ctx := utils.GetRedisClient()
+	fileInfoUnmarshalData, _ := rdb.HGet(ctx, "015:fileInfoMap", fileId).Result()
+
+	if fileInfoUnmarshalData != "" {
+		var fileInfoData RedisFileInfo
+		if err := json.Unmarshal([]byte(fileInfoUnmarshalData), &fileInfoData); err != nil {
+			return RedisFileInfo{}, err
+		}
+		return fileInfoData, nil
+	}
+	return RedisFileInfo{}, errors.New("db不存在该文件信息")
+}