Add support for list background import

pkg/models/tasks.go

@@ -131,7 +131,7 @@ type Task struct {
 
 type TaskWithComments struct {
 	Task
-	Comments []*TaskComment
+	Comments []*TaskComment `xorm:"-" json:"comments"`
 }
 
 // TableName returns the table name for listtasks

pkg/modules/migration/vikunja-file/vikunja.go

@@ -99,6 +99,19 @@ func (v *VikunjaFileMigrator) Migrate(user *user.User, file io.ReaderAt, size in
 
 	for _, n := range namespaces {
 		for _, l := range n.Lists {
+			if b, exists := storedFiles[l.BackgroundFileID]; exists {
+				bf, err := b.Open()
+				if err != nil {
+					return fmt.Errorf("could not open list background file %d for reading: %s", l.BackgroundFileID, err)
+				}
+				var buf bytes.Buffer
+				if _, err := buf.ReadFrom(bf); err != nil {
+					return fmt.Errorf("could not read list background file %d: %s", l.BackgroundFileID, err)
+				}
+
+				l.BackgroundInformation = &buf
+			}
+
 			for _, t := range l.Tasks {
 				for _, label := range t.Labels {
 					label.ID = 0