/// <summary>
/// Method to check whether the user with given token already rated the instance with given
/// </summary>
/// <returns>
/// Returns UserRate instance if there is one. Returns null if the user hasn't rated the instance
/// </returns>v
public static UserRate CheckRateLogged(INewsFeedAPIContext db, string token, int id)
{
var currentUserRates = from userRate in db.UserRates
where userRate.Token == token
select userRate;
var currentRatedNews = from userRate in currentUserRates
where userRate.NewsInstanceID == id
select userRate;
return(currentRatedNews.Count() > 0 ? currentRatedNews.First() : null);
}
/// <summary>
/// Method to remove the rating that is given in UserRate instance
/// </summary>
/// <returns>
/// Returns an instance with modified rating
/// </returns>
public static NewsInstance CancelRate(INewsFeedAPIContext db, UserRate rate)
{
db.UserRates.Remove(db.UserRates.Find(rate.ID));
var currentNewsInstance = db.NewsInstances.Find(rate.NewsInstanceID);
currentNewsInstance.RateCount--;
currentNewsInstance.RateSum -= rate.Rating;
db.MarkAsModified(currentNewsInstance);
db.SaveChanges();
return(currentNewsInstance);
}
/// <summary>
/// Method to add given rating to an instance with given id
/// </summary>
/// <returns>
/// Returns an instance with modified rating
/// </returns>
public static NewsInstance RateNews(INewsFeedAPIContext db, int id, int rating)
{
NewsInstance newsInstance = db.NewsInstances.Find(id);
if (newsInstance != null)
{
newsInstance.RateSum += rating;
newsInstance.RateCount++;
db.MarkAsModified(newsInstance);
db.SaveChanges();
}
return(newsInstance);
}
/// <summary>
/// Method to generate a token based on constant values defined in TokenProvider
/// </summary>
/// <returns>
/// Returns generated token as string value
/// </returns>
public static string GetToken(INewsFeedAPIContext db)
{
while (true)
{
var token = new string(Enumerable.Repeat(chars, tokenLength).Select(s => s[random.Next(s.Length)]).ToArray());
if ((from userRate in db.UserRates where userRate.Token == token select userRate).Count() == 0)
{
db.UserRates.Add(new UserRate {
Token = token, NewsInstanceID = -1, Rating = -1
});
db.SaveChanges();
return(token);
}
}
}
/// <summary>
/// Method to log an information about a rate given by a user with given token
/// </summary>
/// <returns>
/// Returns bool result showing whether a rate was logged. Returns false if user with given token already rated the instance with given id
/// </returns>
/// <exception cref="UnregistredTokenException">Thrown in case given token was not issued by the system </exception>
/// <exception cref="RatingOutOfBoundsException">Thrown in case given rate does not fit the range attribute for the property </exception>
public static void TryLogRating(INewsFeedAPIContext db, string token, int id, int rating, out LoggingError loggingError)
{
var ratesWithGivenToken = from userRate in db.UserRates
where userRate.Token == token
select userRate;
if (rating < minRating || rating > maxRating)
{
loggingError = LoggingError.RatingOutOfBounds;
return;
}
if (ratesWithGivenToken.Count() < 1)
{
loggingError = LoggingError.UnregistredToken;
return;
}
var newsRatedWithGivenToken = from userRate in ratesWithGivenToken
where userRate.NewsInstanceID == id
select userRate;
if (newsRatedWithGivenToken.Count() > 0)
{
loggingError = LoggingError.NoNewsRated;
return;
}
db.UserRates.Add(new UserRate {
Token = token, NewsInstanceID = id, Rating = rating
});
try
{
db.SaveChanges();
}
catch (DBConcurrencyException)
{
loggingError = LoggingError.SavingError;
return;
}
loggingError = LoggingError.NoError;
}
public UserRatingController(INewsFeedAPIContext context)
{
db = context;
}
public NewsInstancesController(INewsFeedAPIContext context)
{
db = context;
}
