private static JsonapiPagination ExtractPagination(IEnumerable <KeyValuePair <string, string> > parameters)
{
var hasPageNumberParam = parameters.Any(e => e.Key == PageNumberQueryParam);
var hasPageSizeParam = parameters.Any(e => e.Key == PageSizeQueryParam);
var pageNumber = 0;
var pageSize = DefaultPageSize;
if (!hasPageNumberParam && !hasPageSizeParam)
{
return(null);
}
if (hasPageNumberParam && !int.TryParse(parameters.FirstOrDefault(e => e.Key == PageNumberQueryParam).Value, out pageNumber))
{
throw new InvalidCastException("Page number must be a positive integer.");
}
if (hasPageSizeParam && !int.TryParse(parameters.FirstOrDefault(e => e.Key == PageSizeQueryParam).Value, out pageSize))
{
throw new InvalidCastException("Page size must be a positive integer.");
}
if (pageNumber < 0)
{
throw new NotSupportedException("Page number must not be negative.");
}
if (pageSize <= 0)
{
throw new NotSupportedException("Page size must be greater than or equal to 1.");
}
JsonapiPagination pagination = new JsonapiPagination();
pagination.PageNumber = pageNumber;
pagination.PageSize = pageSize;
return(pagination);
}
public static IQueryable <T> GeneratePagination <T>(this IQueryable <T> query, JsonapiPagination pagination)
{
if (pagination != null)
{
if (pagination.PageSize > 100)
{
throw new InvalidCastException("Page size must be less than 100");
}
query = query.Skip((pagination.PageNumber - 1) * pagination.PageSize).Take(pagination.PageSize);
}
return(query);
}