api schema check

services/user_service/schemas.py

@@ -108,10 +108,21 @@ class UserLogin(BaseModel):
     @classmethod
     def validate_password_bytes(cls, v):
         """Ensure password doesn't exceed bcrypt's 72-byte limit."""
+        if not v or len(v.strip()) == 0:
+            raise ValueError("Password cannot be empty")
         password_bytes = v.encode('utf-8')
         if len(password_bytes) > 72:
             raise ValueError("Password is too long when encoded as UTF-8 (max 72 bytes for bcrypt)")
         return v
+    
+    @field_validator("username")
+    @classmethod
+    def validate_login_fields(cls, v, info):
+        """Ensure at least email or username is provided."""
+        email = info.data.get('email')
+        if not email and not v:
+            raise ValueError("Either email or username must be provided")
+        return v
 
 
 class Token(BaseModel):