C#•3mo ago

✅ How to handle errors in services/controllers

Hi! I do most of work in services and then call the method in the controller. What's the proper way to handle errors that occur in service? I need return error to the frontend (the error model must be consistent). Is it fine to throw error in the services or is there a better way? Here is example of AccountService method

public async Task RegisterAsync(RegisterDto dto)
{
    IdentityUser? foundUser = await _userManager.FindByEmailAsync(dto.Email);

    if (foundUser != null)
    {
        throw new Exception($"Email '{dto.Email}' is already registered");
    }

    IdentityUser userToCreate = new IdentityUser
    {
        UserName = dto.Email,
        Email = dto.Email
    };

    IdentityResult result = await _userManager.CreateAsync(userToCreate, dto.Password);

    if (!result.Succeeded)
    {
        throw new Exception($"Failed to create user:{string.Join(',', result.Errors.Select(e => e.Description))}");
    }
}

public async Task RegisterAsync(RegisterDto dto)
{
    IdentityUser? foundUser = await _userManager.FindByEmailAsync(dto.Email);

    if (foundUser != null)
    {
        throw new Exception($"Email '{dto.Email}' is already registered");
    }

    IdentityUser userToCreate = new IdentityUser
    {
        UserName = dto.Email,
        Email = dto.Email
    };

    IdentityResult result = await _userManager.CreateAsync(userToCreate, dto.Password);

    if (!result.Succeeded)
    {
        throw new Exception($"Failed to create user:{string.Join(',', result.Errors.Select(e => e.Description))}");
    }
}

6 Replies

Angius•3mo ago

Just make sure the exceptions make sense (so no generic Exception) and handled them in the exception-handling middleware Basically, throw a custom NotFoundException or a ConflictException Then, in the exception-handling middleware do something like

return exception switch {
    NotFoundException => new NotFoundResult(),
    ConflictException => new ConflictResult(),
    // ...
    _ => new ServerErrorResult()
};

return exception switch {
    NotFoundException => new NotFoundResult(),
    ConflictException => new ConflictResult(),
    // ...
    _ => new ServerErrorResult()
};

Otherwise, any exception you throw will result in 500 Internal Server Error

Alex•3mo ago

okay, thank you

Angius•3mo ago

Alternatively, use some sort of a result pattern

Alex•3mo ago

I'll check it and decide which one is more suitable

sibber•3mo ago

$close if you have no further questions :)

MODiX•3mo ago

Use the /close command to mark a forum thread as answered

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✅ How to handle errors in services/controllers