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// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Web.Http.Internal;
using System.Web.Http.Properties;
namespace System.Web.Http.Query
{
/// <summary>
/// Used to deserialize a set of string based query operations into expressions and
/// compose them over a specified query.
/// </summary>
internal static class ODataQueryDeserializer
{
/// <summary>
/// Deserializes the query operations in the specified Uri and applies them
/// to the specified IQueryable.
/// </summary>
/// <param name="query">The root query to compose the deserialized query over.</param>
/// <param name="uri">The request Uri containing the query operations.</param>
/// <returns>The resulting IQueryable with the deserialized query composed over it.</returns>
public static IQueryable Deserialize(IQueryable query, Uri uri)
{
if (query == null)
{
throw Error.ArgumentNull("query");
}
if (uri == null)
{
throw Error.ArgumentNull("uri");
}
ServiceQuery serviceQuery = GetServiceQuery(uri);
return Deserialize(query, serviceQuery.QueryParts, null);
}
/// <summary>
/// Deserializes the query operations in the specified Uri and returns an IQueryable
/// with a manufactured query root with those operations applied.
/// </summary>
/// <typeparam name="T">The element type of the query</typeparam>
/// <param name="uri">The request Uri containing the query operations.</param>
/// <returns>The resulting IQueryable with the deserialized query composed over it.</returns>
public static IQueryable<T> Deserialize<T>(Uri uri)
{
if (uri == null)
{
throw Error.ArgumentNull("uri");
}
return (IQueryable<T>)Deserialize(typeof(T), uri);
}
/// <summary>
/// Deserializes the query operations in the specified Uri and returns an IQueryable
/// with a manufactured query root with those operations applied.
/// </summary>
/// <param name="elementType">The element type of the query</param>
/// <param name="uri">The request Uri containing the query operations.</param>
/// <returns>The resulting IQueryable with the deserialized query composed over it.</returns>
public static IQueryable Deserialize(Type elementType, Uri uri)
{
if (elementType == null)
{
throw Error.ArgumentNull("elementType");
}
if (uri == null)
{
throw Error.ArgumentNull("uri");
}
ServiceQuery serviceQuery = GetServiceQuery(uri);
Array array = Array.CreateInstance(elementType, 0);
IQueryable baseQuery = ((IEnumerable)array).AsQueryable();
return Deserialize(baseQuery, serviceQuery.QueryParts, null);
}
internal static IQueryable Deserialize(IQueryable query, IEnumerable<ServiceQueryPart> queryParts)
{
if (query == null)
{
throw Error.ArgumentNull("query");
}
if (queryParts == null)
{
throw Error.ArgumentNull("queryParts");
}
return Deserialize(query, queryParts, null);
}
internal static IQueryable Deserialize(IQueryable query, IEnumerable<ServiceQueryPart> queryParts, QueryResolver queryResolver)
{
if (query == null)
{
throw Error.ArgumentNull("query");
}
if (queryParts == null)
{
throw Error.ArgumentNull("queryParts");
}
foreach (ServiceQueryPart part in queryParts)
{
switch (part.QueryOperator)
{
case "filter":
try
{
query = DynamicQueryable.Where(query, part.Expression, queryResolver);
}
catch (ParseException e)
{
throw new ParseException(
Error.Format(SRResources.ParseErrorInClause, "$filter", e.Message));
}
break;
case "orderby":
try
{
query = DynamicQueryable.OrderBy(query, part.Expression, queryResolver);
}
catch (ParseException e)
{
throw new ParseException(
Error.Format(SRResources.ParseErrorInClause, "$orderby", e.Message));
}
break;
case "skip":
try
{
int skipCount = Convert.ToInt32(part.Expression, System.Globalization.CultureInfo.InvariantCulture);
if (skipCount < 0)
{
throw new ParseException(
Error.Format(SRResources.PositiveIntegerExpectedForODataQueryParameter, "$skip", part.Expression));
}
query = DynamicQueryable.Skip(query, skipCount);
}
catch (FormatException e)
{
throw new ParseException(
Error.Format(SRResources.ParseErrorInClause, "$skip", e.Message));
}
break;
case "top":
try
{
int topCount = Convert.ToInt32(part.Expression, System.Globalization.CultureInfo.InvariantCulture);
if (topCount < 0)
{
throw new ParseException(
Error.Format(SRResources.PositiveIntegerExpectedForODataQueryParameter, "$top", part.Expression));
}
query = DynamicQueryable.Take(query, topCount);
}
catch (FormatException e)
{
throw new ParseException(
Error.Format(SRResources.ParseErrorInClause, "$top", e.Message));
}
break;
}
}
return query;
}
internal static ServiceQuery GetServiceQuery(Uri uri)
{
if (uri == null)
{
throw Error.ArgumentNull("uri");
}
NameValueCollection queryPartCollection = UriQueryUtility.ParseQueryString(uri.Query);
List<ServiceQueryPart> serviceQueryParts = new List<ServiceQueryPart>();
foreach (string queryPart in queryPartCollection)
{
if (queryPart == null || !queryPart.StartsWith("$", StringComparison.Ordinal))
{
// not a special query string
continue;
}
foreach (string value in queryPartCollection.GetValues(queryPart))
{
string queryOperator = queryPart.Substring(1);
if (!ServiceQuery.IsSupportedQueryOperator(queryOperator))
{
// skip any operators we don't support
continue;
}
ServiceQueryPart serviceQueryPart = new ServiceQueryPart(queryOperator, value);
serviceQueryParts.Add(serviceQueryPart);
}
}
// Query parts for OData need to be ordered $filter, $orderby, $skip, $top. For this
// set of query operators, they are already in alphabetical order, so it suffices to
// order by operator name. In the future if we support other operators, this may need
// to be reexamined.
serviceQueryParts = serviceQueryParts.OrderBy(p => p.QueryOperator).ToList();
ServiceQuery serviceQuery = new ServiceQuery()
{
QueryParts = serviceQueryParts,
};
return serviceQuery;
}
}
}
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