feat(backend): handle username always in lowercase

This should make all usernames of new users into lowercase. Usernames are also searched in the DB as lowercase.

Signed-off-by: Philip Molares <philip.molares@udo.edu>
Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

backend/src/users/user-info.dto.ts

@@ -1,12 +1,13 @@
 /*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { ApiProperty } from '@nestjs/swagger';
-import { IsString } from 'class-validator';
+import { IsLowercase, IsString } from 'class-validator';
 
 import { BaseDto } from '../utils/base.dto.';
+import { Username } from '../utils/username';
 
 export class UserInfoDto extends BaseDto {
   /**
@@ -14,8 +15,9 @@ export class UserInfoDto extends BaseDto {
    * @example "john.smith"
    */
   @IsString()
+  @IsLowercase()
   @ApiProperty()
-  username: string;
+  username: Username;
 
   /**
    * The display name

backend/src/users/user.entity.ts

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
@@ -20,6 +20,7 @@ import { HistoryEntry } from '../history/history-entry.entity';
 import { Identity } from '../identity/identity.entity';
 import { MediaUpload } from '../media/media-upload.entity';
 import { Note } from '../notes/note.entity';
+import { Username } from '../utils/username';
 
 @Entity()
 export class User {
@@ -29,7 +30,7 @@ export class User {
   @Column({
     unique: true,
   })
-  username: string;
+  username: Username;
 
   @Column()
   displayName: string;
@@ -77,7 +78,7 @@ export class User {
   private constructor() {}
 
   public static create(
-    username: string,
+    username: Username,
     displayName: string,
   ): Omit<User, 'id' | 'createdAt' | 'updatedAt'> {
     const newUser = new User();

backend/src/users/users.service.ts

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
@@ -9,6 +9,7 @@ import { Repository } from 'typeorm';
 
 import { AlreadyInDBError, NotInDBError } from '../errors/errors';
 import { ConsoleLoggerService } from '../logger/console-logger.service';
+import { Username } from '../utils/username';
 import {
   FullUserInfoDto,
   UserInfoDto,
@@ -29,12 +30,12 @@ export class UsersService {
   /**
    * @async
    * Create a new user with a given username and displayName
-   * @param username - the username the new user shall have
-   * @param displayName - the display name the new user shall have
+   * @param {Username} username - the username the new user shall have
+   * @param {string} displayName - the display name the new user shall have
    * @return {User} the user
    * @throws {AlreadyInDBError} the username is already taken.
    */
-  async createUser(username: string, displayName: string): Promise<User> {
+  async createUser(username: Username, displayName: string): Promise<User> {
     const user = User.create(username, displayName);
     try {
       return await this.userRepository.save(user);
@@ -77,12 +78,12 @@ export class UsersService {
   /**
    * @async
    * Get the user specified by the username
-   * @param {string} username the username by which the user is specified
+   * @param {Username} username the username by which the user is specified
    * @param {UserRelationEnum[]} [withRelations=[]] if the returned user object should contain certain relations
    * @return {User} the specified user
    */
   async getUserByUsername(
-    username: string,
+    username: Username,
     withRelations: UserRelationEnum[] = [],
   ): Promise<User> {
     const user = await this.userRepository.findOne({