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using Linq2Rest.Parser;
using Nancy;
using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
/// <summary>
/// This is a modified version of Nancy.OData
/// https://github.com/adamhathcock/Nancy.OData
///
/// It adds natural sorting on the results, because Linq2Rest/OData doesn't support custom orderby functions.
///
/// </summary>
///
namespace BCR
{
public static class ODataExtensions
{
private const string ODATA_URI_KEY = "OData_Uri";
private static NameValueCollection ParseUriOptions(NancyContext context)
{
object item;
if (context.Items.TryGetValue(ODATA_URI_KEY, out item))
{
return item as NameValueCollection;
}
NameValueCollection nv = new NameValueCollection();
context.Items.Add(ODATA_URI_KEY, nv);
var queryString = context.Request.Url.Query;
if (string.IsNullOrWhiteSpace(queryString))
{
return nv;
}
if (!queryString.StartsWith("?"))
{
throw new InvalidOperationException("Invalid OData query string " + queryString);
}
var parameters = queryString.Substring(1).Split('&', '=');
if (parameters.Length % 2 != 0)
{
throw new InvalidOperationException("Invalid OData query string " + queryString);
}
for (int i = 0; i < parameters.Length; i += 2)
{
nv.Add(parameters[i], Uri.UnescapeDataString(parameters[i + 1]));
}
return nv;
}
public static string GetReflectedPropertyValueAsString(this object subject, string field)
{
object reflectedValue = subject.GetType().GetProperty(field).GetValue(subject, null);
return reflectedValue != null ? reflectedValue.ToString() : "";
}
public static object GetReflectedPropertyValue(this object subject, string field)
{
return subject.GetType().GetProperty(field).GetValue(subject, null);
}
public static bool ReflectedPropertyIsString(this object subject, string field)
{
return subject.GetType().GetProperty(field).GetType() == typeof(bool);
}
/// <summary>
/// Returns a filtered and ordered result set.
/// Uses natural sort.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="context"></param>
/// <param name="modelItems">The objects to filter</param>
/// <param name="totalCount">The total number of items in the resultset before paging.</param>
/// <returns></returns>
public static IEnumerable<object> ApplyODataUriFilter<T>(this NancyContext context, IEnumerable<T> modelItems, ref int totalCount)
{
NameValueCollection nv = ParseUriOptions(context);
// Perform sorting ourselves, because linq2rest doesn't allow custom comparers.
// In order to use a custom sort function, we should first retrieve all filtered objects without paging (i.e. remove $skip and $top).
// Then sort the objects and lastly apply the paging and select.
NameValueCollection pagingNV = new NameValueCollection();
if (null != nv.Get("$skip"))
{
pagingNV.Add("$skip", nv.Get("$skip"));
nv.Remove("$skip");
}
if (null != nv.Get("$top"))
{
pagingNV.Add("$top", nv.Get("$top"));
nv.Remove("$top");
}
// Remove select as well, as we need to be able to cast the objects to T type after sorting.
if (null != nv.Get("$select"))
{
pagingNV.Add("$select", nv.Get("$select"));
nv.Remove("$select");
}
string sortOption = nv.Get("$orderby");
nv.Remove("$orderby");
// Do a query that returns all records using the supplied filter parameters, so we can sort them ourselves.
// As we removed the $select filter, the returned objects are still of type T.
var parser = new ParameterParser<T>();
var filter = parser.Parse(nv);
var objects = filter.Filter(modelItems).Cast<T>();
totalCount = objects.Count();
// Now sort
if (null != sortOption)
{
char[] delimiterChars = { ',' };
string[] orderby = sortOption.Split(delimiterChars);
string[] field = new string[orderby.Length];
bool[] ascending = new bool[orderby.Length];
char[] delimiterSpace = { ' ' };
for (int i = 0; i < orderby.Length; i++)
{
string[] terms = orderby[i].Split(delimiterSpace);
field[i] = terms[0];
ascending[i] = true;
if (terms.Count() == 2)
ascending[i] = terms[1] != "desc";
}
// TODO: generalize the comparer selection.
if (typeof(T) == typeof(Comic))
{
if (orderby.Count() == 1)
{
objects = objects.OrderBy(item => item as Comic, new ComicComparer(field[0], ascending[0]));
}
else
if (orderby.Count() == 2)
{
objects = objects.OrderBy(item => item as Comic, new ComicComparer(field[0], ascending[0]))
.ThenBy(item => item as Comic, new ComicComparer(field[1], ascending[1]));
}
else
if (orderby.Count() >= 3)
{
objects = objects.OrderBy(item => item as Comic, new ComicComparer(field[0], ascending[0]))
.ThenBy(item => item as Comic, new ComicComparer(field[1], ascending[1]))
.ThenBy(item => item as Comic, new ComicComparer(field[2], ascending[2]));
}
}
else
{
// Uhg, use natural sort on every field.....
// This must change someday.
if (orderby.Count() == 1)
{
objects = objects.OrderBy(item => item.GetReflectedPropertyValueAsString(field[0]), new NaturalSortComparer(ascending[0]));
}
else
if (orderby.Count() == 2)
{
objects = objects.OrderBy(item => item.GetReflectedPropertyValueAsString(field[0]), new NaturalSortComparer(ascending[0]))
.ThenBy(item => item.GetReflectedPropertyValueAsString(field[1]), new NaturalSortComparer(ascending[1]));
}
else
if (orderby.Count() >= 3)
{
objects = objects.OrderBy(item => item.GetReflectedPropertyValueAsString(field[0]), new NaturalSortComparer(ascending[0]))
.ThenBy(item => item.GetReflectedPropertyValueAsString(field[1]), new NaturalSortComparer(ascending[1]))
.ThenBy(item => item.GetReflectedPropertyValueAsString(field[2]), new NaturalSortComparer(ascending[2]));
}
}
}
// Now limit the resultset by applying the paging and select options.
var parser2 = new ParameterParser<T>();
var filter2 = parser2.Parse(pagingNV);
var objects2 = filter2.Filter(objects.Cast<T>());
return objects2;
}
public static Response AsOData<T>(this IResponseFormatter formatter, IEnumerable<T> modelItems, HttpStatusCode code = HttpStatusCode.OK)
{
// BCR only supports json, no need to supply and check the $format every time....
int totalCount = 0;
return formatter.AsJson(formatter.Context.ApplyODataUriFilter(modelItems, ref totalCount), code);
}
}
}
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