public void ProcessQuery(QueryDescriptorQueryNode query)
{
_sparqlModel = new SparqlModel();
switch (query.Query.Kind)
{
case QueryNodeKind.EntitySet:
ProcessNode(query.Query as EntitySetQueryNode);
break;
case QueryNodeKind.KeyLookup:
ProcessRoot(query.Query as KeyLookupQueryNode);
break;
case QueryNodeKind.Filter:
var entityType = (query.Query as FilterQueryNode).ItemType;
var instances = AssertInstancesVariable(entityType);
_entitySetVariable = instances;
ProcessFilter(query.Query as FilterQueryNode);
_sparqlModel.AddSelectVariable(instances, entityType.FullName(), true);
_sparqlModel.IsDescribe = true;
break;
case QueryNodeKind.Top:
case QueryNodeKind.Skip:
ProcessNode(query.Query);
break;
case QueryNodeKind.Segment:
var navigation = query.Query as NavigationPropertyNode;
var finalVar = ProcessNode(navigation);
_sparqlModel.AddSelectVariable(
finalVar.ToString(),
navigation.TypeReference.FullName(),
navigation.NavigationProperty.OwnMultiplicity() == EdmMultiplicity.Many);
_sparqlModel.IsDescribe = true;
break;
default:
throw new NotImplementedException("No processing implemented for " + query.Query.Kind);
}
// Apply page size limit
if (!_sparqlModel.Limit.HasValue || _sparqlModel.Limit.Value > _maxPageSize)
{
_sparqlModel.OriginalLimit = _sparqlModel.Limit;
_sparqlModel.Limit = _maxPageSize;
}
}
public void ProcessQuery(QueryDescriptorQueryNode query)
{
_sparqlModel = new SparqlModel();
switch (query.Query.Kind)
{
case QueryNodeKind.EntitySet:
ProcessNode(query.Query as EntitySetQueryNode);
break;
case QueryNodeKind.KeyLookup:
ProcessRoot(query.Query as KeyLookupQueryNode);
break;
case QueryNodeKind.Filter:
var entityType = (query.Query as FilterQueryNode).ItemType;
var instances = AssertInstancesVariable(entityType);
_entitySetVariable = instances;
ProcessFilter(query.Query as FilterQueryNode);
_sparqlModel.AddSelectVariable(instances, entityType.FullName(), true);
_sparqlModel.IsDescribe = true;
break;
case QueryNodeKind.Top:
case QueryNodeKind.Skip:
ProcessNode(query.Query);
break;
case QueryNodeKind.Segment:
var navigation = query.Query as NavigationPropertyNode;
var finalVar = ProcessNode(navigation);
_sparqlModel.AddSelectVariable(
finalVar.ToString(),
navigation.TypeReference.FullName(),
navigation.NavigationProperty.OwnMultiplicity() == EdmMultiplicity.Many);
_sparqlModel.IsDescribe = true;
break;
default:
throw new NotImplementedException("No processing implemented for " + query.Query.Kind);
}
// Apply page size limit
if (!_sparqlModel.Limit.HasValue || _sparqlModel.Limit.Value > _maxPageSize)
{
_sparqlModel.OriginalLimit = _sparqlModel.Limit;
_sparqlModel.Limit = _maxPageSize;
}
}
private Uri GetNextPageLink(SparqlModel originalQueryModel)
{
if (!originalQueryModel.Limit.HasValue)
{
// No limit in the original query so there should be no next page
return(null);
}
if (!originalQueryModel.OriginalLimit.HasValue ||
originalQueryModel.OriginalLimit.Value > originalQueryModel.Limit.Value)
{
// We need a next page link
var thisPageLink = _request.Url.ToString();
var queryParams = System.Web.HttpUtility.ParseQueryString(_request.Url.Query);
int nextPageStart = originalQueryModel.Offset.HasValue
? originalQueryModel.Offset.Value + originalQueryModel.Limit.Value
: originalQueryModel.Limit.Value;
queryParams["$skip"] = nextPageStart.ToString(CultureInfo.InvariantCulture);
string updatedQuery = "?" + String.Join("&",
queryParams.AllKeys.Select(
k => String.Format("{0}={1}", k, queryParams[k])));
return(new Uri(_request.Url, updatedQuery));
}
return(null);
}
/// <summary>
/// Creates an OData feed response containing a list of entries for a particular type of entity
/// </summary>
/// <param name="resultsGraph">The RDF graph containing the SPARQL results</param>
/// <param name="entityType">The fully qualified domain name for the type of entity to be written</param>
/// <param name="resultsCount">The count of the total number of results that the server can provide</param>
/// <param name="originalQueryModel">The SPARQL query that was executed to generate this graph</param>
public void CreateFeedFromGraph(IGraph resultsGraph, string entityType, int resultsCount, SparqlModel originalQueryModel = null)
{
var msgWriter = new ODataMessageWriter(_response, _writerSettings, _map.Model);
var feedWriter = msgWriter.CreateODataFeedWriter();
var entries = new List<ODataEntry>();
var typeUri = _map.GetUriForType(entityType);
if (!String.IsNullOrEmpty(typeUri))
{
var predNode = resultsGraph.CreateUriNode(UriFactory.Create(RdfConstants.RdfType));
var objNode = resultsGraph.CreateUriNode(UriFactory.Create(typeUri));
if (originalQueryModel == null || originalQueryModel.Ordering == null)
{
// No sorting required, just iterate all instances
foreach (var instanceTriple in resultsGraph.GetTriplesWithPredicateObject(predNode, objNode))
{
var instanceUri = (instanceTriple.Subject as IUriNode).Uri;
entries.Add(CreateODataEntry(resultsGraph, instanceUri.ToString(), entityType));
}
}
else
{
// We need to apply the same sort criteria to this graph to ensure
// that the ODATA results are properly sorted.
// NOTE: This will only work if all the properties used in the original query
// are present in the graph - this could be a problem with more complex traversals
// and the query may instead need to be rewritten / regenerated to extract only
// the required sort properties.
originalQueryModel.IsDescribe = false;
var resultsTable =
resultsGraph.ExecuteQuery(originalQueryModel.GetSparqlRepresentation()) as SparqlResultSet;
var targetVariable= originalQueryModel.SelectVariables[0];
foreach (var result in resultsTable.Results)
{
var instanceUriNode = result[targetVariable] as IUriNode;
if (instanceUriNode != null)
{
entries.Add(CreateODataEntry(resultsGraph, instanceUriNode.Uri.ToString(), entityType));
}
}
}
}
var feed = new ODataFeed {Id = _baseUri + _map.GetTypeSet(entityType)};
if (_writerSettings.Version >= ODataVersion.V2)
{
feed.Count = resultsCount;
}
if (originalQueryModel != null)
{
feed.NextPageLink = GetNextPageLink(originalQueryModel);
}
feedWriter.WriteStart(feed);
foreach (var entry in entries)
{
feedWriter.WriteStart(entry);
feedWriter.WriteEnd();
}
feedWriter.WriteEnd();
feedWriter.Flush();
}
private Uri GetNextPageLink(SparqlModel originalQueryModel)
{
if (!originalQueryModel.Limit.HasValue)
{
// No limit in the original query so there should be no next page
return null;
}
if (!originalQueryModel.OriginalLimit.HasValue ||
originalQueryModel.OriginalLimit.Value > originalQueryModel.Limit.Value)
{
// We need a next page link
var thisPageLink = _request.Url.ToString();
var queryParams = System.Web.HttpUtility.ParseQueryString(_request.Url.Query);
int nextPageStart = originalQueryModel.Offset.HasValue
? originalQueryModel.Offset.Value + originalQueryModel.Limit.Value
: originalQueryModel.Limit.Value;
queryParams["$skip"] = nextPageStart.ToString(CultureInfo.InvariantCulture);
string updatedQuery = "?" + String.Join("&",
queryParams.AllKeys.Select(
k => String.Format("{0}={1}", k, queryParams[k])));
return new Uri(_request.Url, updatedQuery);
}
return null;
}
/// <summary>
/// Creates an OData feed response containing a list of entries for a particular type of entity
/// </summary>
/// <param name="resultsGraph">The RDF graph containing the SPARQL results</param>
/// <param name="entityType">The fully qualified domain name for the type of entity to be written</param>
/// <param name="resultsCount">The count of the total number of results that the server can provide</param>
/// <param name="originalQueryModel">The SPARQL query that was executed to generate this graph</param>
public void CreateFeedFromGraph(IGraph resultsGraph, string entityType, int resultsCount, SparqlModel originalQueryModel = null)
{
var msgWriter = new ODataMessageWriter(_response, _writerSettings, _map.Model);
var feedWriter = msgWriter.CreateODataFeedWriter();
var entries = new List <ODataEntry>();
var typeUri = _map.GetUriForType(entityType);
if (!String.IsNullOrEmpty(typeUri))
{
var predNode = resultsGraph.CreateUriNode(UriFactory.Create(RdfConstants.RdfType));
var objNode = resultsGraph.CreateUriNode(UriFactory.Create(typeUri));
if (originalQueryModel == null || originalQueryModel.Ordering == null)
{
// No sorting required, just iterate all instances
foreach (var instanceTriple in resultsGraph.GetTriplesWithPredicateObject(predNode, objNode))
{
var instanceUri = (instanceTriple.Subject as IUriNode).Uri;
entries.Add(CreateODataEntry(resultsGraph, instanceUri.ToString(), entityType));
}
}
else
{
// We need to apply the same sort criteria to this graph to ensure
// that the ODATA results are properly sorted.
// NOTE: This will only work if all the properties used in the original query
// are present in the graph - this could be a problem with more complex traversals
// and the query may instead need to be rewritten / regenerated to extract only
// the required sort properties.
originalQueryModel.IsDescribe = false;
var resultsTable =
resultsGraph.ExecuteQuery(originalQueryModel.GetSparqlRepresentation()) as SparqlResultSet;
var targetVariable = originalQueryModel.SelectVariables[0];
foreach (var result in resultsTable.Results)
{
var instanceUriNode = result[targetVariable] as IUriNode;
if (instanceUriNode != null)
{
entries.Add(CreateODataEntry(resultsGraph, instanceUriNode.Uri.ToString(), entityType));
}
}
}
}
var feed = new ODataFeed {
Id = _baseUri + _map.GetTypeSet(entityType)
};
if (_writerSettings.Version >= ODataVersion.V2)
{
feed.Count = resultsCount;
}
if (originalQueryModel != null)
{
feed.NextPageLink = GetNextPageLink(originalQueryModel);
}
feedWriter.WriteStart(feed);
foreach (var entry in entries)
{
feedWriter.WriteStart(entry);
feedWriter.WriteEnd();
}
feedWriter.WriteEnd();
feedWriter.Flush();
}