feat(backend): allow changing username in PATCH /users/@me

backend/db/member.go

@@ -30,13 +30,13 @@ const (
 	ErrMemberNameInUse = errors.Sentinel("member name already in use")
 )
 
-func (db *DB) Member(ctx context.Context, id xid.ID) (m Member, err error) {
+func (db *DB) getMember(ctx context.Context, q pgxscan.Querier, id xid.ID) (m Member, err error) {
 	sql, args, err := sq.Select("*").From("members").Where("id = ?", id).ToSql()
 	if err != nil {
 		return m, errors.Wrap(err, "building sql")
 	}
 
-	err = pgxscan.Get(ctx, db, &m, sql, args...)
+	err = pgxscan.Get(ctx, q, &m, sql, args...)
 	if err != nil {
 		if errors.Cause(err) == pgx.ErrNoRows {
 			return m, ErrMemberNotFound
@@ -47,6 +47,10 @@ func (db *DB) Member(ctx context.Context, id xid.ID) (m Member, err error) {
 	return m, nil
 }
 
+func (db *DB) Member(ctx context.Context, id xid.ID) (m Member, err error) {
+	return db.getMember(ctx, db, id)
+}
+
 // UserMember returns a member scoped by user.
 func (db *DB) UserMember(ctx context.Context, userID xid.ID, memberRef string) (m Member, err error) {
 	sql, args, err := sq.Select("*").From("members").
@@ -98,6 +102,7 @@ func (db *DB) CreateMember(ctx context.Context, tx pgx.Tx, userID xid.ID, name s
 	if err != nil {
 		pge := &pgconn.PgError{}
 		if errors.As(err, &pge) {
+			// unique constraint violation
 			if pge.Code == "23505" {
 				return m, ErrMemberNameInUse
 			}
@@ -146,7 +151,7 @@ func (db *DB) UpdateMember(
 	avatarURLs []string,
 ) (m Member, err error) {
 	if name == nil && displayName == nil && bio == nil && links == nil && avatarURLs == nil {
-		return m, ErrNothingToUpdate
+		return db.getMember(ctx, tx, id)
 	}
 
 	builder := sq.Update("members").Where("id = ?", id)

backend/db/user.go

@@ -113,9 +113,8 @@ func (u *User) UpdateFromDiscord(ctx context.Context, db pgxscan.Querier, du *di
 	return pgxscan.Get(ctx, db, u, sql, args...)
 }
 
-// User gets a user by ID.
+func (db *DB) getUser(ctx context.Context, q pgxscan.Querier, id xid.ID) (u User, err error) {
-func (db *DB) User(ctx context.Context, id xid.ID) (u User, err error) {
+	err = pgxscan.Get(ctx, q, &u, "select * from users where id = $1", id)
-	err = pgxscan.Get(ctx, db, &u, "select * from users where id = $1", id)
 	if err != nil {
 		if errors.Cause(err) == pgx.ErrNoRows {
 			return u, ErrUserNotFound
@@ -127,6 +126,11 @@ func (db *DB) User(ctx context.Context, id xid.ID) (u User, err error) {
 	return u, nil
 }
 
+// User gets a user by ID.
+func (db *DB) User(ctx context.Context, id xid.ID) (u User, err error) {
+	return db.getUser(ctx, db, id)
+}
+
 // Username gets a user by username.
 func (db *DB) Username(ctx context.Context, name string) (u User, err error) {
 	err = pgxscan.Get(ctx, db, &u, "select * from users where username = $1", name)
@@ -151,6 +155,32 @@ func (db *DB) UsernameTaken(ctx context.Context, username string) (valid, taken
 	return true, taken, err
 }
 
+// UpdateUsername validates the given username, then updates the given user's name to it if valid.
+func (db *DB) UpdateUsername(ctx context.Context, tx pgx.Tx, id xid.ID, newName string) error {
+	if !usernameRegex.MatchString(newName) {
+		return ErrInvalidUsername
+	}
+
+	sql, args, err := sq.Update("users").Set("username", newName).Where("id = ?", id).ToSql()
+	if err != nil {
+		return errors.Wrap(err, "building sql")
+	}
+
+	_, err = db.Exec(ctx, sql, args...)
+	if err != nil {
+		pge := &pgconn.PgError{}
+		if errors.As(err, &pge) {
+			// unique constraint violation
+			if pge.Code == "23505" {
+				return ErrUsernameTaken
+			}
+		}
+
+		return errors.Wrap(err, "executing query")
+	}
+	return nil
+}
+
 func (db *DB) UpdateUser(
 	ctx context.Context,
 	tx pgx.Tx, id xid.ID,
@@ -159,7 +189,7 @@ func (db *DB) UpdateUser(
 	avatarURLs []string,
 ) (u User, err error) {
 	if displayName == nil && bio == nil && links == nil && avatarURLs == nil {
-		return u, ErrNothingToUpdate
+		return db.getUser(ctx, tx, id)
 	}
 
 	builder := sq.Update("users").Where("id = ?", id)

backend/routes/user/patch_user.go

@@ -12,6 +12,7 @@ import (
 )
 
 type PatchUserRequest struct {
+	Username    *string       `json:"username"`
 	DisplayName *string       `json:"display_name"`
 	Bio         *string       `json:"bio"`
 	Links       *[]string     `json:"links"`
@@ -34,8 +35,15 @@ func (s *Server) patchUser(w http.ResponseWriter, r *http.Request) error {
 		return server.APIError{Code: server.ErrBadRequest}
 	}
 
+	// get existing user, for comparison later
+	u, err := s.DB.User(ctx, claims.UserID)
+	if err != nil {
+		return errors.Wrap(err, "getting existing user")
+	}
+
 	// validate that *something* is set
-	if req.DisplayName == nil &&
+	if req.Username == nil &&
+		req.DisplayName == nil &&
 		req.Bio == nil &&
 		req.Links == nil &&
 		req.Fields == nil &&
@@ -130,7 +138,22 @@ func (s *Server) patchUser(w http.ResponseWriter, r *http.Request) error {
 	}
 	defer tx.Rollback(ctx)
 
-	u, err := s.DB.UpdateUser(ctx, tx, claims.UserID, req.DisplayName, req.Bio, req.Links, avatarURLs)
+	// update username
+	if req.Username != nil && *req.Username != u.Username {
+		err = s.DB.UpdateUsername(ctx, tx, claims.UserID, *req.Username)
+		if err != nil {
+			switch err {
+			case db.ErrUsernameTaken:
+				return server.APIError{Code: server.ErrUsernameTaken}
+			case db.ErrInvalidUsername:
+				return server.APIError{Code: server.ErrInvalidUsername}
+			default:
+				return errors.Wrap(err, "updating username")
+			}
+		}
+	}
+
+	u, err = s.DB.UpdateUser(ctx, tx, claims.UserID, req.DisplayName, req.Bio, req.Links, avatarURLs)
 	if err != nil && errors.Cause(err) != db.ErrNothingToUpdate {
 		log.Errorf("updating user: %v", err)
 		return err