Init V4 community edition (#2265)

* Init V4 community edition

* Init V4 community edition

application/migrator/model/file.go

@@ -0,0 +1,39 @@
+package model
+
+import (
+	"github.com/jinzhu/gorm"
+)
+
+// File 文件
+type File struct {
+	// 表字段
+	gorm.Model
+	Name            string `gorm:"unique_index:idx_only_one"`
+	SourceName      string `gorm:"type:text"`
+	UserID          uint   `gorm:"index:user_id;unique_index:idx_only_one"`
+	Size            uint64
+	PicInfo         string
+	FolderID        uint `gorm:"index:folder_id;unique_index:idx_only_one"`
+	PolicyID        uint
+	UploadSessionID *string `gorm:"index:session_id;unique_index:session_only_one"`
+	Metadata        string  `gorm:"type:text"`
+
+	// 关联模型
+	Policy Policy `gorm:"PRELOAD:false,association_autoupdate:false"`
+
+	// 数据库忽略字段
+	Position           string            `gorm:"-"`
+	MetadataSerialized map[string]string `gorm:"-"`
+}
+
+// Thumb related metadata
+const (
+	ThumbStatusNotExist     = ""
+	ThumbStatusExist        = "exist"
+	ThumbStatusNotAvailable = "not_available"
+
+	ThumbStatusMetadataKey  = "thumb_status"
+	ThumbSidecarMetadataKey = "thumb_sidecar"
+
+	ChecksumMetadataKey = "webdav_checksum"
+)