Generate a random list identifier based on the list title

pkg/migration/20200516123847.go

@@ -0,0 +1,57 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-2020 Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package migration
+
+import (
+	"code.vikunja.io/api/pkg/models"
+	"src.techknowlogick.com/xormigrate"
+	"xorm.io/xorm"
+)
+
+func init() {
+	migrations = append(migrations, &xormigrate.Migration{
+		ID:          "20200516123847",
+		Description: "Generate a list identifier for each list",
+		Migrate: func(tx *xorm.Engine) error {
+			lists := []*models.List{}
+			err := tx.Find(&lists)
+			if err != nil {
+				return err
+			}
+
+			for _, l := range lists {
+				if l.Identifier != "" {
+					continue
+				}
+
+				err := models.GenerateListIdentifier(l, tx)
+				if err != nil {
+					return err
+				}
+				_, err = tx.Where("id = ?", l.ID).Update(l)
+				if err != nil {
+					return err
+				}
+			}
+
+			return nil
+		},
+		Rollback: func(tx *xorm.Engine) error {
+			return nil
+		},
+	})
+}

pkg/models/list.go

@@ -21,7 +21,9 @@ import (
 	"code.vikunja.io/api/pkg/timeutil"
 	"code.vikunja.io/api/pkg/user"
 	"code.vikunja.io/web"
+	"strings"
 	"xorm.io/builder"
+	"xorm.io/xorm"
 )
 
 // List represents a list of tasks
@@ -351,6 +353,43 @@ func (l *List) CheckIsArchived() (err error) {
 	return nil
 }
 
+// GenerateListIdentifier generates a unique random list identifier based on the list title.
+// If it is not able to find one, the list identifier will be empty.
+func GenerateListIdentifier(l *List, sess *xorm.Engine) (err error) {
+
+	// The general idea here is to take the title and slice it into pieces, until we found a unique piece.
+
+	var exists = true
+	titleSlug := strings.Replace(strings.ToUpper(l.Title), " ", "", -1)
+
+	// We can save at most 10 characters in the db, so we need to ensure it has at most 10 characters
+	if len(titleSlug) > 10 {
+		titleSlug = titleSlug[0:9]
+	}
+
+	var i = 0
+
+	for exists {
+
+		// Prevent endless looping
+		if i == len(titleSlug) {
+			break
+		}
+
+		// Take a random part of the title slug, starting at the beginning
+		l.Identifier = titleSlug[i:]
+		exists, err = sess.
+			Where("identifier = ?", l.Identifier).
+			And("id != ?", l.ID).
+			Exist(&List{})
+		if err != nil {
+			return
+		}
+		i++
+	}
+	return nil
+}
+
 // CreateOrUpdateList updates a list or creates it if it doesn't exist
 func CreateOrUpdateList(list *List) (err error) {
 
@@ -376,6 +415,14 @@ func CreateOrUpdateList(list *List) (err error) {
 		}
 	}
 
+	// Generate a random list identifier base on the list title
+	if list.ID == 0 && list.Identifier == "" {
+		err = GenerateListIdentifier(list, x)
+		if err != nil {
+			return
+		}
+	}
+
 	if list.ID == 0 {
 		_, err = x.Insert(list)
 		metrics.UpdateCount(1, metrics.ListCountKey)