public void Apply(SparqlResultSet results)
{
switch (this._type)
{
case SparqlResultsType.Boolean:
results.SetResult(this._r);
break;
case SparqlResultsType.VariableBindings:
foreach (String var in this._vars)
{
results.AddVariable(var);
}
foreach (SparqlResult res in this._results)
{
results.AddResult(res);
}
break;
default:
throw new RdfParseException("The type property of a serialized SparqlResultSet did not contain a valid value");
}
}
public void Apply(SparqlResultSet results)
{
switch (_type)
{
case SparqlResultsType.Boolean:
results.SetResult(_r);
break;
case SparqlResultsType.VariableBindings:
foreach (String var in _vars)
{
results.AddVariable(var);
}
foreach (SparqlResult res in _results)
{
results.AddResult(res);
}
break;
default:
throw new RdfParseException("The type property of a serialized SparqlResultSet did not contain a valid value");
}
}
/// <summary>
/// Handles a Variable Declaration by adding the Variable to the Result Set.
/// </summary>
/// <param name="var">Variable Name.</param>
/// <returns></returns>
protected override bool HandleVariableInternal(string var)
{
_results.AddVariable(var);
return(true);
}
/// <summary>
/// Executes a SPARQL Query on the native Quad Store
/// </summary>
/// <param name="sparqlQuery">SPARQL Query to execute</param>
/// <returns></returns>
/// <remarks>
/// <para>
/// This method will first attempt to parse the query into a <see cref="SparqlQuery">SparqlQuery</see> object. If this succeeds then the Query Type can be used to determine how to handle the response.
/// </para>
/// <para>
/// If the parsing fails then the query will be executed anyway using Virtuoso's SPASQL (SPARQL + SQL) syntax. Parsing can fail because Virtuoso supports various SPARQL extensions which the library does not support. These include things like aggregate functions but also SPARQL Update statements.
/// </para>
/// <para>
/// If you use an aggregate query which has an Integer, Decimal or Double type result then you will receive a <see cref="SparqlResultSet">SparqlResultSet</see> containing a single <see cref="SparqlResult">SparqlResult</see> which has contains a binding for a variable named <strong>Result</strong> which contains a <see cref="LiteralNode">LiteralNode</see> typed to the appropriate datatype.
/// </para>
/// </remarks>
/// <exception cref="RdfQueryException">Thrown if an error occurs in making the query</exception>
public Object Query(String sparqlQuery)
{
Object finalResult = null;
DataTable results = new DataTable();
results.Columns.CollectionChanged += new System.ComponentModel.CollectionChangeEventHandler(Columns_CollectionChanged);
//See if the query can be parsed into a SparqlQuery object
//It might not since the user might use Virtuoso's extensions to Sparql in their query
try
{
//We'll set the Parser to SPARQL 1.1 mode even though Virtuoso's SPARQL implementation has
//various perculiarties in their SPARQL 1.1 implementation and we'll try and
//handle the potential results in the catch branch if a valid SPARQL 1.0 query
//cannot be parsed
//Change made in response to a bug report by Aleksandr A. Zaripov [[email protected]]
SparqlQueryParser parser = new SparqlQueryParser();
parser.SyntaxMode = SparqlQuerySyntax.Sparql_1_1;
SparqlQuery query = parser.ParseFromString(sparqlQuery);
switch (query.QueryType)
{
case SparqlQueryType.Select:
case SparqlQueryType.SelectAll:
case SparqlQueryType.SelectAllDistinct:
case SparqlQueryType.SelectAllReduced:
case SparqlQueryType.SelectDistinct:
case SparqlQueryType.SelectReduced:
//Type the Tables columns as System.Object
foreach (SparqlVariable var in query.Variables)
{
if (var.IsResultVariable)
{
results.Columns.Add(var.Name, typeof(System.Object));
}
}
break;
}
try
{
this.Open(false);
//Make the Query against Virtuoso
VirtuosoCommand cmd = this._db.CreateCommand();
cmd.CommandText = "SPARQL " + sparqlQuery;
VirtuosoDataAdapter adapter = new VirtuosoDataAdapter(cmd);
adapter.Fill(results);
//Decide how to process the results based on the return type
switch (query.QueryType)
{
case SparqlQueryType.Ask:
//Expect a DataTable containing a single row and column which contains a boolean
if (results.Rows.Count == 1 && results.Columns.Count == 1)
{
bool result;
int r;
if (Boolean.TryParse(results.Rows[0][0].ToString(), out result))
{
finalResult = new SparqlResultSet(result);
}
else if (Int32.TryParse(results.Rows[0][0].ToString(), out r))
{
if (r == 1)
{
finalResult = new SparqlResultSet(true);
}
else
{
finalResult = new SparqlResultSet(false);
}
}
else
{
throw new RdfQueryException("Expected a Boolean as the result of an ASK query but the non-boolean value '" + results.Rows[0][0].ToString() + "' was received");
}
}
else
{
//If we get anything else then we'll return that the result was False
finalResult = new SparqlResultSet(false);
}
break;
case SparqlQueryType.Construct:
case SparqlQueryType.Describe:
case SparqlQueryType.DescribeAll:
//Expect a DataTable containing a single row and column which contains a String
//That string will be a Turtle serialization of the Graph
if (results.Rows.Count == 1 && results.Columns.Count == 1)
{
try
{
//Use StringParser to parse
String data = results.Rows[0][0].ToString();
TurtleParser ttlparser = new TurtleParser();
Graph g = new Graph();
StringParser.Parse(g, data, ttlparser);
finalResult = g;
}
catch (RdfParseException parseEx)
{
throw new RdfQueryException("Expected a valid Turtle serialization of the Graph resulting from a CONSTRUCT/DESCRIBE query but the result failed to parse", parseEx);
}
}
else
{
throw new RdfQueryException("Expected a single string value representing the serialization of the Graph resulting from a CONSTRUCT/DESCRIBE query but this was not received");
}
break;
case SparqlQueryType.Select:
case SparqlQueryType.SelectAll:
case SparqlQueryType.SelectAllDistinct:
case SparqlQueryType.SelectAllReduced:
case SparqlQueryType.SelectDistinct:
case SparqlQueryType.SelectReduced:
//Expect a DataTable containing columns for each Result Variable and a row for each solution
SparqlResultSet rset = new SparqlResultSet();
rset.SetResult(true);
//Get Result Variables
List<SparqlVariable> resultVars = query.Variables.Where(v => v.IsResultVariable).ToList();
foreach (SparqlVariable var in resultVars)
{
rset.AddVariable(var.Name);
}
Graph temp = new Graph();
//Convert each solution into a SPARQLResult
foreach (DataRow r in results.Rows)
{
SparqlResult result = new SparqlResult();
foreach (SparqlVariable var in resultVars)
{
if (r[var.Name] != null)
{
result.SetValue(var.Name, this.LoadNode(temp, r[var.Name]));
}
}
rset.AddResult(result);
}
finalResult = rset;
break;
default:
throw new RdfQueryException("Unable to process the Results of an Unknown query type");
}
this.Close(false);
}
catch
{
this.Close(true, true);
throw;
}
}
catch (RdfParseException)
{
//Unable to parse a SPARQL 1.0 query
//Have to attempt to detect the return type based on the DataTable that
//the SPASQL (Sparql+SQL) query gives back
//Make the Query against Virtuoso
VirtuosoCommand cmd = this._db.CreateCommand();
cmd.CommandText = "SPARQL " /*define output:format '_JAVA_' "*/ + sparqlQuery;
VirtuosoDataAdapter adapter = new VirtuosoDataAdapter(cmd);
adapter.Fill(results);
//Try to detect the return type based on the DataTable configuration
if (results.Rows.Count == 0 && results.Columns.Count > 0)
{
//No Rows but some columns implies empty SELECT results
SparqlResultSet rset = new SparqlResultSet();
foreach (DataColumn col in results.Columns)
{
rset.AddVariable(col.ColumnName);
}
finalResult = rset;
}
else if (results.Rows.Count == 1 && results.Columns.Count == 1 && !Regex.IsMatch(sparqlQuery, "SELECT", RegexOptions.IgnoreCase))
{
//Added a fix here suggested by Alexander Sidorov - not entirely happy with this fix as what happens if SELECT just happens to occur in a URI/Variable Name?
//Single Row and Column implies ASK/DESCRIBE/CONSTRUCT results
bool result;
int r;
decimal rdec;
double rdbl;
float rflt;
if (results.Rows[0][0].ToString().Equals(String.Empty))
{
//Empty Results
finalResult = new SparqlResultSet();
}
else if (Boolean.TryParse(results.Rows[0][0].ToString(), out result))
{
//Parseable Boolean so ASK Results
finalResult = new SparqlResultSet(result);
}
else if (Int32.TryParse(results.Rows[0][0].ToString(), out r))
{
//Parseable Integer so Aggregate SELECT Query Results
SparqlResultSet rset = new SparqlResultSet();
rset.AddVariable("Result");
SparqlResult res = new SparqlResult();
res.SetValue("Result", new LiteralNode(null, r.ToString(), new Uri(XmlSpecsHelper.XmlSchemaDataTypeInteger)));
rset.AddResult(res);
finalResult = rset;
}
else if (Single.TryParse(results.Rows[0][0].ToString(), out rflt))
{
//Parseable Single so Aggregate SELECT Query Results
SparqlResultSet rset = new SparqlResultSet();
rset.AddVariable("Result");
SparqlResult res = new SparqlResult();
res.SetValue("Result", new LiteralNode(null, rflt.ToString(), new Uri(XmlSpecsHelper.XmlSchemaDataTypeFloat)));
rset.AddResult(res);
finalResult = rset;
}
else if (Double.TryParse(results.Rows[0][0].ToString(), out rdbl))
{
//Parseable Double so Aggregate SELECT Query Results
SparqlResultSet rset = new SparqlResultSet();
rset.AddVariable("Result");
SparqlResult res = new SparqlResult();
res.SetValue("Result", new LiteralNode(null, rdbl.ToString(), new Uri(XmlSpecsHelper.XmlSchemaDataTypeDouble)));
rset.AddResult(res);
finalResult = rset;
}
else if (Decimal.TryParse(results.Rows[0][0].ToString(), out rdec))
{
//Parseable Decimal so Aggregate SELECT Query Results
SparqlResultSet rset = new SparqlResultSet();
rset.AddVariable("Result");
SparqlResult res = new SparqlResult();
res.SetValue("Result", new LiteralNode(null, rdec.ToString(), new Uri(XmlSpecsHelper.XmlSchemaDataTypeDecimal)));
rset.AddResult(res);
finalResult = rset;
}
else
{
//String so try and parse as Turtle
try
{
//Use StringParser to parse
String data = results.Rows[0][0].ToString();
TurtleParser ttlparser = new TurtleParser();
Graph g = new Graph();
StringParser.Parse(g, data, ttlparser);
finalResult = g;
}
catch (RdfParseException)
{
//If it failed to parse then it might be the result of one of the aggregate
//functions that Virtuoso extends Sparql with
Graph temp = new Graph();
SparqlResultSet rset = new SparqlResultSet();
rset.AddVariable(results.Columns[0].ColumnName);
SparqlResult res = new SparqlResult();
res.SetValue(results.Columns[0].ColumnName, this.LoadNode(temp, results.Rows[0][0]));
//Nothing was returned here previously - fix submitted by Aleksandr A. Zaripov [[email protected]]
rset.AddResult(res);
finalResult = rset;
}
}
}
else
{
//Any other number of rows/columns we have to assume that it's normal SELECT results
//Changed in response to bug report by Aleksandr A. Zaripov [[email protected]]
//SELECT Query Results
SparqlResultSet rset = new SparqlResultSet();
rset.SetResult(true);
//Get Result Variables
foreach (DataColumn col in results.Columns)
{
rset.AddVariable(col.ColumnName);
}
Graph temp = new Graph();
//Convert each solution into a SPARQLResult
foreach (DataRow r in results.Rows)
{
SparqlResult result = new SparqlResult();
foreach (String var in rset.Variables)
{
if (r[var] != null)
{
result.SetValue(var, this.LoadNode(temp, r[var]));
}
}
rset.AddResult(result);
}
finalResult = rset;
}
}
return finalResult;
}