Add validate username by regex =)

src/core/application/user/dto/user.py

@@ -8,7 +8,9 @@ class LoginUserDTO(BaseModel):
 
 
 class RegisterUserDTO(BaseModel):
-    username: str = Field(min_length=3, max_length=64)
+    username: str = Field(
+        min_length=3, max_length=64, pattern=r"^[a-zA-Z0-9_]*$"
+    )
     email: EmailStr = Field(max_length=100)
     password: SecretStr = Field(min_length=6, max_length=64)
 

src/core/domain/user/entities/user.py

@@ -1,5 +1,6 @@
 from dataclasses import dataclass
 from uuid import UUID
+import re
 
 from core.domain.user.entities.role import RoleEntity
 
@@ -20,3 +21,8 @@ def _validate(self):
             raise ValueError("Email is too long")
         if not 3 <= len(self.username) <= 64:
             raise ValueError("Username must be between 3 and 64 characters")
+        pattern = re.compile(r"^[a-zA-Z0-9_]+$")
+        if not pattern.match(self.username):
+            raise ValueError(
+                "Username must only contain letters, numbers, and underscores."
+            )

src/presentation/app/blueprints/auth/forms.py

@@ -9,12 +9,24 @@
     Length,
     Email,
     EqualTo,
+    Regexp,
 )
 
 
 class RegistrationForm(FlaskForm):
     username = StringField(
-        "Username", validators=[DataRequired(), Length(min=3, max=64)]
+        "Username",
+        validators=[
+            DataRequired(),
+            Length(min=3, max=64),
+            Regexp(
+                r"^[a-zA-Z0-9_]+$",
+                message=(
+                    "Username must only contain letters, "
+                    "numbers, and underscores."
+                ),
+            ),
+        ],
     )
     email = StringField(
         "Email", validators=[DataRequired(), Email(), Length(max=100)]

src/presentation/app/blueprints/auth/templates/register.html

@@ -15,7 +15,8 @@ <h2>Реєстрація</h2>
                 {{ form.hidden_tag() }}
                 <div class="form-group {% if form.username.errors %}has-error{% endif %}">
                     {{ form.username.label }}
-                    {{ form.username(size=32, class_="form-control") }}
+                    {{ form.username(size=32, class_="form-control", pattern="^[a-zA-Z0-9_]+$", title="Username must
+                    only contain letters, numbers, and underscores") }}
                     <div class="error-message">
                         {% for error in form.username.errors %}
                         {{ error }}