public ActionResult Create(CreateQuestionInputModel inputModel)
{
if (inputModel != null && this.ModelState.IsValid)
{
this.ValidateAnswers(inputModel.Answers);
if (this.ModelState.IsValid)
{
var context = new VotingSystemEntities();
var newQuestion = new Question { Content = inputModel.Content, RequireNames = inputModel.RequireNames };
this.AddQuestionAnswers(inputModel.Answers, newQuestion);
this.GenerateQuestionUrlId(newQuestion);
context.Questions.Add(newQuestion);
context.SaveChanges();
return Redirect("/Vote/Index/" + newQuestion.UrlId);
}
}
return this.View("~/Views/Home/Index.cshtml", inputModel ?? new CreateQuestionInputModel());
}
private void AddQuestionAnswers(List<string> answers, Question question)
{
foreach (var answer in answers)
{
if (!string.IsNullOrWhiteSpace(answer))
{
question.Answers.Add(new Answer { Content = answer });
}
}
}
private void GenerateQuestionUrlId(Question newQuestion)
{
string allowedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
int length = 10;
const int ByteSize = 0x100;
const int BufferSize = 128;
if (length < 0)
{
throw new ArgumentOutOfRangeException(nameof(length), "length cannot be less than zero.");
}
if (string.IsNullOrEmpty(allowedChars))
{
throw new ArgumentException("allowedChars may not be empty.");
}
var allowedCharSet = new HashSet<char>(allowedChars).ToArray();
if (ByteSize < allowedCharSet.Length)
{
throw new ArgumentException($"allowedChars may contain no more than {ByteSize} characters.");
}
// Guid.NewGuid and System.Random are not particularly random. By using a
// cryptographically-secure random number generator, the caller is always
// protected, regardless of use.
using (var rng = new System.Security.Cryptography.RNGCryptoServiceProvider())
{
var result = new StringBuilder();
var buffer = new byte[BufferSize];
while (result.Length < length)
{
rng.GetBytes(buffer);
for (var i = 0; i < buffer.Length && result.Length < length; i++)
{
// Divide the byte into allowedCharSet-sized groups. If the
// random value falls into the last group and the last group is
// too small to choose from the entire allowedCharSet, ignore
// the value in order to avoid biasing the result.
var outOfRangeStart = ByteSize - (ByteSize % allowedCharSet.Length);
if (outOfRangeStart <= buffer[i])
{
continue;
}
result.Append(allowedCharSet[buffer[i] % allowedCharSet.Length]);
}
}
newQuestion.UrlId = result.ToString();
}
}
