fs: add Optional ID() method to Object and implement it in backends

ID() shows the internal ID of the Object if available.

backend/amazonclouddrive/amazonclouddrive.go

@@ -1315,6 +1315,14 @@ func (f *Fs) changeNotifyRunner(notifyFunc func(string, fs.EntryType), checkpoin
 	return checkpoint
 }
 
+// ID returns the ID of the Object if known, or "" if not
+func (o *Object) ID() string {
+	if o.info.Id == nil {
+		return ""
+	}
+	return *o.info.Id
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs     = (*Fs)(nil)
@@ -1326,4 +1334,5 @@ var (
 	_ fs.ChangeNotifier  = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
 	_ fs.MimeTyper       = &Object{}
+	_ fs.IDer            = &Object{}
 )

backend/b2/b2.go

@@ -1422,6 +1422,11 @@ func (o *Object) MimeType() string {
 	return o.mimeType
 }
 
+// ID returns the ID of the Object if known, or "" if not
+func (o *Object) ID() string {
+	return o.id
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs          = &Fs{}
@@ -1431,4 +1436,5 @@ var (
 	_ fs.ListRer     = &Fs{}
 	_ fs.Object      = &Object{}
 	_ fs.MimeTyper   = &Object{}
+	_ fs.IDer        = &Object{}
 )

backend/box/box.go

@@ -1048,6 +1048,11 @@ func (o *Object) Remove() error {
 	return o.fs.deleteObject(o.id)
 }
 
+// ID returns the ID of the Object if known, or "" if not
+func (o *Object) ID() string {
+	return o.id
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs              = (*Fs)(nil)
@@ -1058,4 +1063,5 @@ var (
 	_ fs.DirMover        = (*Fs)(nil)
 	_ fs.DirCacheFlusher = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
+	_ fs.IDer            = (*Object)(nil)
 )

backend/drive/drive.go

@@ -1678,6 +1678,11 @@ func (o *Object) MimeType() string {
 	return o.mimeType
 }
 
+// ID returns the ID of the Object if known, or "" if not
+func (o *Object) ID() string {
+	return o.id
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs              = (*Fs)(nil)
@@ -1695,4 +1700,5 @@ var (
 	_ fs.Abouter         = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
 	_ fs.MimeTyper       = (*Object)(nil)
+	_ fs.IDer            = (*Object)(nil)
 )

backend/mega/mega.go

@@ -1110,6 +1110,11 @@ func (o *Object) Remove() error {
 	return nil
 }
 
+// ID returns the ID of the Object if known, or "" if not
+func (o *Object) ID() string {
+	return o.info.GetHash()
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs              = (*Fs)(nil)
@@ -1122,4 +1127,5 @@ var (
 	_ fs.MergeDirser     = (*Fs)(nil)
 	_ fs.Abouter         = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
+	_ fs.IDer            = (*Object)(nil)
 )

backend/onedrive/onedrive.go

@@ -1302,6 +1302,11 @@ func (o *Object) MimeType() string {
 	return o.mimeType
 }
 
+// ID returns the ID of the Object if known, or "" if not
+func (o *Object) ID() string {
+	return o.id
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs     = (*Fs)(nil)
@@ -1313,4 +1318,5 @@ var (
 	_ fs.Abouter         = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
 	_ fs.MimeTyper       = &Object{}
+	_ fs.IDer            = &Object{}
 )

backend/opendrive/opendrive.go

@@ -1086,6 +1086,11 @@ func (o *Object) readMetaData() (err error) {
 	return nil
 }
 
+// ID returns the ID of the Object if known, or "" if not
+func (o *Object) ID() string {
+	return o.id
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs              = (*Fs)(nil)
@@ -1095,4 +1100,5 @@ var (
 	_ fs.DirMover        = (*Fs)(nil)
 	_ fs.DirCacheFlusher = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
+	_ fs.IDer            = (*Object)(nil)
 )

backend/pcloud/pcloud.go

@@ -1118,6 +1118,11 @@ func (o *Object) Remove() error {
 	})
 }
 
+// ID returns the ID of the Object if known, or "" if not
+func (o *Object) ID() string {
+	return o.id
+}
+
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs              = (*Fs)(nil)
@@ -1129,4 +1134,5 @@ var (
 	_ fs.DirCacheFlusher = (*Fs)(nil)
 	_ fs.Abouter         = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
+	_ fs.IDer            = (*Object)(nil)
 )

fs/fs.go

@@ -246,6 +246,12 @@ type MimeTyper interface {
 	MimeType() string
 }
 
+// IDer is an optional interface for Object
+type IDer interface {
+	// ID returns the ID of the Object if known, or "" if not
+	ID() string
+}
+
 // ObjectUnWrapper is an optional interface for Object
 type ObjectUnWrapper interface {
 	// UnWrap returns the Object that this Object is wrapping or