/// <summary>Executes a SPARQL query and returns resulting quads</summary>
/// <param name="queryModel">Query model to be executed.</param>
/// <returns>Enumeration of entity quads beeing a result of the query.</returns>
public IEnumerable<EntityQuad> ExecuteEntityQuery(Query queryModel)
{
SparqlQueryVariables variables;
var resultSet = ExecuteSelect(GetSparqlQuery(queryModel, out variables));
return from result in resultSet
let id = (result[variables.Entity] is IBlankNode ?
new BlankId(((IBlankNode)result[variables.Entity]).InternalID, null, ((IUriNode)result[variables.MetaGraph]).Uri) :
new EntityId(((IUriNode)result[variables.Entity]).Uri))
let s = result[variables.Subject].WrapNode(id)
let p = result[variables.Predicate].WrapNode(id)
let o = result[variables.Object].WrapNode(id)
let g = result[variables.MetaGraph].WrapNode(id)
select new EntityQuad(id, s, p, o, g);
}
/// <summary>Returns a resulting collection of a query.</summary>
/// <typeparam name="T">Type of elements to be returned.</typeparam>
/// <param name="queryModel">Query model to be parsed.</param>
/// <returns>Enumeration of resulting entities matching given query.</returns>
public IEnumerable <T> ExecuteCollection <T>(QueryModel queryModel)
{
IEnumerable <CastResultOperator> resultOperators = queryModel.ResultOperators.OfType <CastResultOperator>().ToArray();
foreach (CastResultOperator resultOperator in resultOperators)
{
queryModel.ResultOperators.Remove(resultOperator);
}
Model.Query sparqlQuery = VisitQueryModel(queryModel);
IEnumerable <EntityId> actualEntities;
IEnumerable <RomanticWeb.Model.IEntityQuad> quads = _entitySource.ExecuteEntityQuery(sparqlQuery, out actualEntities);
IEnumerable <T> result = (!typeof(IEntity).IsAssignableFrom(typeof(T)) ? CreateLiteralResultSet <T>(quads, actualEntities) : CreateEntityResultSet <T>(quads, actualEntities));
foreach (CastResultOperator resultOperator in resultOperators)
{
var castMethod = EnumerableCastMethod.MakeGenericMethod(resultOperator.CastItemType);
result = (IEnumerable <T>)castMethod.Invoke(null, new object[] { result });
}
return(result);
}
/// <summary>Visits a select clause.</summary>
/// <param name="selectClause">Select clause to be visited.</param>
/// <param name="queryModel">Query model containing given select clause.</param>
public override void VisitSelectClause(SelectClause selectClause, Remotion.Linq.QueryModel queryModel)
{
QuerySourceReferenceExpression querySource = FindQuerySource(selectClause.Selector);
_visitor.VisitExpression(selectClause.Selector);
QueryComponent component = _visitor.RetrieveComponent();
_query = _visitor.Query;
_mainFromComponent = _query.FindAllComponents<StrongEntityAccessor>().Where(item => item.SourceExpression == querySource.ReferencedQuerySource).First();
if (_query.Subject == null)
{
_query.Subject = _mainFromComponent.About;
UnboundConstrain genericConstrain = new UnboundConstrain(new Identifier("s"), new Identifier("p"), new Identifier("o"), _mainFromComponent.SourceExpression.FromExpression);
_mainFromComponent.Elements.Insert(0, genericConstrain);
_query.Select.Add(genericConstrain);
}
_subject = _query.Subject;
queryModel.MainFromClause.Accept(this, queryModel);
_query.Select.Add(_mainFromComponent);
VisitBodyClauses(queryModel.BodyClauses, queryModel);
VisitResultOperators(queryModel.ResultOperators, queryModel);
OverrideSelector(component, selectClause.Selector);
}
/// <summary>Visit a query.</summary>
/// <param name="query">Query to be visited.</param>
public override void VisitQuery(Query query)
{
InitQuery(query.IsSubQuery ? null : query.Prefixes);
BeginQuery(query.IsSubQuery, query.QueryForm, query.Select, query.CreateVariableName);
_entityAccessorToExpand = ((query.Limit >= 0) || (query.Offset >= 0) || (query.OrderBy.Count > 0) ? (StrongEntityAccessor)query.Elements.LastOrDefault(item => item is StrongEntityAccessor) : null);
foreach (QueryElement element in query.Elements)
{
VisitComponent(element);
}
EndQuery(query.IsSubQuery, (_entityAccessorToExpand != null ? query.OrderBy : null));
}
/// <summary>Creates a new blank query that can act as a sub query for this instance.</summary>
/// <param name="subject">Primary subject of the resulting query.</param>
/// <remarks>This method doesn't add the resulting query as a sub query of this instance.</remarks>
/// <returns>Query that can act as a sub query for this instance.</returns>
public Query CreateSubQuery(Identifier subject)
{
Query result = new Query(subject, _variableNamingStrategy);
result.OwnerQuery = this;
return result;
}
protected GenericSparqlQueryVisitor VisitModel(Query queryModel)
{
GenericSparqlQueryVisitor visitor = new GenericSparqlQueryVisitor();
visitor.MetaGraphUri = new Uri("http://app.magi/graphs");
visitor.VisitQuery(queryModel);
return visitor;
}
/// <summary>Visit a query.</summary> /// <param name="query">Query to be visited.</param> public abstract void VisitQuery(Query query);
/// <summary>Executes a SPARQL ask query.</summary>
/// <param name="queryModel">Query model to be executed.</param>
/// <returns><b>true</b> in case a given query has solution, otherwise <b>false</b>.</returns>
public bool ExecuteAskQuery(Query queryModel)
{
return ExecuteSelect(GetSparqlQuery(queryModel)).Result;
}
/// <summary>Executes a SPARQL query with scalar result.</summary>
/// <param name="queryModel">Query model to be executed.</param>
/// <returns>Scalar value beeing a result of the query.</returns>
public int ExecuteScalarQuery(Query queryModel)
{
SparqlQueryVariables variables;
var resultSet = ExecuteSelect(GetSparqlQuery(queryModel, out variables));
return (from result in resultSet select Int32.Parse(((ILiteralNode)result[variables.Scalar]).Value)).FirstOrDefault();
}
private SparqlQuery GetSparqlQuery(Query sparqlQuery, out SparqlQueryVariables variables)
{
GenericSparqlQueryVisitor queryVisitor = new SparqlQueryVisitor();
queryVisitor.MetaGraphUri = MetaGraphUri;
queryVisitor.VisitQuery(sparqlQuery);
variables = queryVisitor.Variables;
LogTo.Info("RomanticWeb.dotNetRDF.TripleStoreAdapter parsed query: {0}", queryVisitor.CommandText);
SparqlQueryParser parser = new SparqlQueryParser();
return parser.ParseFromString(queryVisitor.CommandText);
}
private SparqlQuery GetSparqlQuery(Query sparqlQuery)
{
SparqlQueryVariables variables;
return GetSparqlQuery(sparqlQuery, out variables);
}
/// <inheritdoc />
public string GetCommandText(QueryModel queryModel)
{
Model.Query sparqlQuery = VisitQueryModel(queryModel);
return(_entitySource.GetCommandText(sparqlQuery));
}
/// <inheritdoc />
public Query Optimize(Query query)
{
return query;
}
/// <summary>Default constructor with query context provided.</summary>
/// <param name="context">Query context to be used as name distinction mechanism.</param>
internal UniqueVariableNamingStrategy(Query context)
{
_context = context;
}
internal EntityQueryModelVisitor(Query query, IEntityContext context)
{
_entityContext = context;
_visitor = new EntityQueryVisitor(_query = (Query)(_result = query), _entityContext);
_subject = null;
}
