public IPaginationTransformResult <T> ApplyPagination <T>(IQueryable <T> query, HttpRequestMessage request)
{
var hasPageNumberParam = false;
var hasPageSizeParam = false;
var pageNumber = 0;
var pageSize = _maxPageSize ?? DefaultPageSize;
foreach (var kvp in request.GetQueryNameValuePairs())
{
if (kvp.Key == PageNumberQueryParam)
{
hasPageNumberParam = true;
if (!int.TryParse(kvp.Value, out pageNumber))
{
throw JsonApiException.CreateForParameterError("Invalid page number",
"Page number must be a positive integer.", PageNumberQueryParam);
}
}
else if (kvp.Key == PageSizeQueryParam)
{
hasPageSizeParam = true;
if (!int.TryParse(kvp.Value, out pageSize))
{
throw JsonApiException.CreateForParameterError("Invalid page size",
"Page size must be a positive integer.", PageSizeQueryParam);
}
}
}
if (!hasPageNumberParam && !hasPageSizeParam)
{
return(new DefaultPaginationTransformResult <T>
{
PagedQuery = query,
PaginationWasApplied = false
});
}
if ((hasPageNumberParam && !hasPageSizeParam))
{
throw JsonApiException.CreateForParameterError("Page size missing",
string.Format("In order for paging to work properly, if either {0} or {1} is set, both must be.",
PageNumberQueryParam, PageSizeQueryParam), PageNumberQueryParam);
}
if (pageNumber < 0)
{
throw JsonApiException.CreateForParameterError("Page number out of bounds",
"Page number must not be negative.", PageNumberQueryParam);
}
if (pageSize <= 0)
{
throw JsonApiException.CreateForParameterError("Page size out of bounds",
"Page size must be greater than or equal to 1.", PageSizeQueryParam);
}
if (_maxPageSize != null && pageSize > _maxPageSize.Value)
{
pageSize = _maxPageSize.Value;
}
if (pageNumber > 0)
{
pageNumber -= 1; // pagination is 1 based in frontend but zero based in backend!
}
var skip = pageNumber * pageSize;
return(new DefaultPaginationTransformResult <T>
{
PageNumber = pageNumber,
PageSize = pageSize,
PagedQuery = query.Skip(skip).Take(pageSize),
PaginationWasApplied = true
});
}
public IOrderedQueryable <T> Sort <T>(IQueryable <T> query, string[] sortExpressions)
{
if (sortExpressions == null || sortExpressions.Length == 0)
{
sortExpressions = new [] { "id" }
}
;
var selectors = new List <ISelector <T> >();
var usedProperties = new Dictionary <PropertyInfo, object>();
var registration = _resourceTypeRegistry.GetRegistrationForType(typeof(T));
foreach (var sortExpression in sortExpressions)
{
if (string.IsNullOrEmpty(sortExpression))
{
throw JsonApiException.CreateForParameterError("Empty sort expression", "One of the sort expressions is empty.", "sort");
}
bool ascending;
string fieldName;
if (sortExpression[0] == '-')
{
ascending = false;
fieldName = sortExpression.Substring(1);
}
else
{
ascending = true;
fieldName = sortExpression;
}
if (string.IsNullOrWhiteSpace(fieldName))
{
throw JsonApiException.CreateForParameterError("Empty sort expression", "One of the sort expressions is empty.", "sort");
}
var paramExpr = Expression.Parameter(typeof(T));
Expression sortValueExpression;
if (fieldName == "id")
{
sortValueExpression = registration.GetSortByIdExpression(paramExpr);
}
else
{
var modelProperty = registration.GetFieldByName(fieldName);
if (modelProperty == null)
{
throw JsonApiException.CreateForParameterError("Attribute not found",
string.Format("The attribute \"{0}\" does not exist on type \"{1}\".",
fieldName, registration.ResourceTypeName), "sort");
}
var property = modelProperty.Property;
if (usedProperties.ContainsKey(property))
{
throw JsonApiException.CreateForParameterError("Attribute specified more than once",
string.Format("The attribute \"{0}\" was specified more than once.", fieldName), "sort");
}
usedProperties[property] = null;
sortValueExpression = Expression.Property(paramExpr, property);
}
var selector = GetSelector <T>(paramExpr, sortValueExpression, !ascending);
selectors.Add(selector);
}
var firstSelector = selectors.First();
IOrderedQueryable <T> workingQuery = firstSelector.ApplyInitially(query);
return(selectors.Skip(1).Aggregate(workingQuery, (current, selector) => selector.ApplySubsequently(current)));
}