refactor/fix: now using pgx errors for postgres error checking instead of trying to look up the error code;

feat: implemented working custom validation;
fix: authservice begin/complete registration

backend/internal/middleware/request.go

@@ -19,9 +19,12 @@ package middleware
 
 import (
 	"easywish/internal/utils/enums"
+	"easywish/internal/validation"
+	"fmt"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	"github.com/go-playground/validator/v10"
 )
 
 type UserInfo struct {
@@ -87,6 +90,15 @@ func RequestMiddleware[T any](role enums.Role) gin.HandlerFunc {
 			return
 		}
 
+		validate := validation.NewValidator()
+
+		if err := validate.Struct(body); err != nil {
+			errorList := err.(validator.ValidationErrors)
+			c.String(http.StatusBadRequest, fmt.Sprintf("Validation error: %s", errorList))
+
+			return
+		}
+
 		request := Request[T]{
 			User: *userInfo,
 			Body: body,

backend/internal/models/auth.go

@@ -23,13 +23,13 @@ type Tokens struct {
 }
 
 type RegistrationBeginRequest struct {
-	Username string  `json:"username" binding:"required,min=3,max=20"`
+	Username string  `json:"username" binding:"required,min=3,max=20" validate:"username"`
 	Email		 *string `json:"email" binding:"email"`
 	Password string  `json:"password" binding:"required"` // TODO: password checking
 }
 
 type RegistrationCompleteRequest struct {
-	Username 					string  `json:"username" binding:"required,min=3,max=20"`
+	Username 					string  `json:"username" binding:"required,min=3,max=20" validate:"username"`
 	VerificationCode	string  `json:"verification_code" binding:"required"`
 	Name							string  `json:"name" binding:"required,max=75"`
 	Birthday					*string `json:"birthday"`
@@ -41,7 +41,7 @@ type RegistrationCompleteResponse struct {
 }
 
 type LoginRequest struct {
-	Username string `json:"username" binding:"required,min=3,max=20"`
+	Username string `json:"username" binding:"required,min=3,max=20" validate:"username"`
 	Password string `json:"password" binding:"required,max=100"`
 	TOTP 		 *string `json:"totp"`
 }

backend/internal/services/auth.go

@@ -23,8 +23,8 @@ import (
 	"easywish/internal/models"
 	"easywish/internal/utils"
 	"easywish/internal/utils/enums"
+	"errors"
 
-	"github.com/jackc/pgerrcode"
 	"github.com/jackc/pgx/v5"
 	"go.uber.org/zap"
 )
@@ -57,7 +57,7 @@ func (a *authServiceImpl) RegistrationBegin(request models.RegistrationBeginRequ
 
 	if user, err = db.TXQueries.CreateUser(db.CTX, request.Username); err != nil {
 
-		if errs.IsPgErr(err, pgerrcode.UniqueViolation) {
+		if errors.Is(err, pgx.ErrNoRows) {
 			a.log.Warn(
 				"Attempted registration for a taken username",
 				zap.String("username", request.Username),
@@ -69,13 +69,13 @@ func (a *authServiceImpl) RegistrationBegin(request models.RegistrationBeginRequ
 		return false, errs.ErrServerError
 	}
 
-	if _, err := db.TXQueries.GetUserByEmail(db.CTX, *request.Email); err == nil {
+	if _, emailerr := db.TXQueries.GetUserByEmail(db.CTX, *request.Email); emailerr == nil {
 		a.log.Warn(
 			"Attempted registration for a taken email",
 			zap.String("email", *request.Email))
 		return false, errs.ErrEmailTaken
 
-	} else if !errs.IsPgErr(err, pgerrcode.NoData) {
+	} else if !errors.Is(emailerr, pgx.ErrNoRows) {
 		a.log.Error(
 			"Failed to check if email is not taken",
 			zap.String("email", *request.Email),
@@ -139,7 +139,7 @@ func (a *authServiceImpl) RegistrationComplete(request models.RegistrationComple
 	user, err = db.TXQueries.GetUserByUsername(db.CTX, request.Username)
 
 	if err != nil {
-		if errs.IsPgErr(err, pgerrcode.NoData) {
+		if errors.Is(err, pgx.ErrNoRows) {
 			a.log.Warn(
 				"Could not find user attempting to complete registration with given username", 
 				zap.String("username", request.Username), 
@@ -161,7 +161,7 @@ func (a *authServiceImpl) RegistrationComplete(request models.RegistrationComple
 	})
 
 	if err != nil {
-		if errs.IsPgErr(err, pgerrcode.NoData) {
+		if errors.Is(err, pgx.ErrNoRows) {
 			a.log.Warn(
 				"User supplied unexistent confirmation code for completing registration",
 				zap.String("username", user.Username),

backend/internal/validation/custom.go

@@ -0,0 +1,52 @@
+// Copyright (c) 2025 Nikolai Papin
+//
+// This file is part of Easywish
+//
+// 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 validation
+
+import (
+	"regexp"
+
+	"github.com/go-playground/validator/v10"
+)
+
+type CustomValidatorHandler struct {
+	Function func(fl validator.FieldLevel) bool
+	FieldName string
+}
+
+func GetCustomHandlers() []CustomValidatorHandler {
+
+	handlers := []CustomValidatorHandler{
+
+		{
+			FieldName: "username",
+			Function: func(fl validator.FieldLevel) bool {
+				username := fl.Field().String()
+        return regexp.MustCompile(`^[a-zA-Z0-9_]{3,20}$`).MatchString(username)
+		}},
+
+		{
+			FieldName: "name",
+			Function: func(fl validator.FieldLevel) bool {
+				username := fl.Field().String()
+        return regexp.MustCompile(`^[.]{1,75}$`).MatchString(username)
+		}},
+
+	} 
+
+	return handlers
+}

backend/internal/validation/setup.go

@@ -1,34 +1,28 @@
 // Copyright (c) 2025 Nikolai Papin
-//
+// 
 // This file is part of Easywish
-//
+// 
 // 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 errors
+package validation
 
 import (
-	"errors"
-
-	"github.com/jackc/pgx/v5/pgconn"
+    "go.uber.org/fx"
 )
 
-func IsPgErr(err error, code string) bool {
-	var pgErr *pgconn.PgError
-	if errors.As(err, &pgErr) {
-		if pgErr.Code == code {
-			return true
-		}
-	}
-	return false
-}
+var Module = fx.Module("validation",
+    fx.Provide(
+			NewValidator,
+    ),
+)

backend/internal/validation/validator.go

@@ -0,0 +1,32 @@
+// Copyright (c) 2025 Nikolai Papin
+//
+// This file is part of Easywish
+//
+// 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 validation
+
+import (
+	"github.com/go-playground/validator/v10"
+)
+
+func NewValidator() *validator.Validate {
+	v := validator.New()
+
+	for _, handler := range GetCustomHandlers() {
+		v.RegisterValidation(handler.FieldName, handler.Function)
+	}
+
+	return v
+}