/// <summary>
/// Gets the row value for the aggregator as number
/// </summary>
internal Double GetRowValueAsNumber(DataRow tableRow)
{
try
{
if (!tableRow.IsNull(this.AggregatorVariable.VariableName))
{
RDFPatternMember rowAggregatorValue = RDFQueryUtilities.ParseRDFPatternMember(tableRow[this.AggregatorVariable.VariableName].ToString());
//PlainLiteral: accepted only if numeric and non-languaged
if (rowAggregatorValue is RDFPlainLiteral)
{
if (String.IsNullOrEmpty(((RDFPlainLiteral)rowAggregatorValue).Language))
{
if (Double.TryParse(rowAggregatorValue.ToString(), NumberStyles.Float, CultureInfo.InvariantCulture, out Double doubleValue))
{
return(doubleValue);
}
}
}
//TypedLiteral: accepted only if numeric
else if (rowAggregatorValue is RDFTypedLiteral)
{
if (((RDFTypedLiteral)rowAggregatorValue).HasDecimalDatatype())
{
return(Double.Parse(((RDFTypedLiteral)rowAggregatorValue).Value, NumberStyles.Float, CultureInfo.InvariantCulture));
}
}
}
return(Double.NaN);
}
catch (Exception ex)
{
RDFQueryEvents.RaiseSELECTQueryEvaluation(String.Format("Exception intercepted during evaluation of RDFAggregator '{0}' in method GetRowValueAsNumber: '{1}'", this, ex.Message));
return(Double.NaN);
}
}
/// <summary>
/// Applies the query to the given SPARQL endpoint
/// </summary>
public RDFSelectQueryResult ApplyToSPARQLEndpoint(RDFSPARQLEndpoint sparqlEndpoint)
{
RDFSelectQueryResult selResult = new RDFSelectQueryResult();
if (sparqlEndpoint != null)
{
RDFQueryEvents.RaiseSELECTQueryEvaluation(String.Format("Evaluating SELECT query on SPARQL endpoint '{0}'...", sparqlEndpoint));
//Establish a connection to the given SPARQL endpoint
using (WebClient webClient = new WebClient())
{
//Insert reserved "query" parameter
webClient.QueryString.Add("query", HttpUtility.UrlEncode(this.ToString()));
//Insert user-provided parameters
webClient.QueryString.Add(sparqlEndpoint.QueryParams);
//Insert request headers
webClient.Headers.Add(HttpRequestHeader.Accept, "application/sparql-results+xml");
//Send querystring to SPARQL endpoint
var sparqlResponse = webClient.DownloadData(sparqlEndpoint.BaseAddress);
//Parse response from SPARQL endpoint
if (sparqlResponse != null)
{
using (var sStream = new MemoryStream(sparqlResponse))
{
selResult = RDFSelectQueryResult.FromSparqlXmlResult(sStream);
}
selResult.SelectResults.TableName = this.ToString();
}
}
//Eventually adjust column names (should start with "?")
Int32 columnsCount = selResult.SelectResults.Columns.Count;
for (Int32 i = 0; i < columnsCount; i++)
{
if (!selResult.SelectResults.Columns[i].ColumnName.StartsWith("?"))
{
selResult.SelectResults.Columns[i].ColumnName = "?" + selResult.SelectResults.Columns[i].ColumnName;
}
}
RDFQueryEvents.RaiseSELECTQueryEvaluation(String.Format("Evaluated SELECT query on SPARQL endpoint '{0}': Found '{1}' results.", sparqlEndpoint, selResult.SelectResultsCount));
}
return(selResult);
}
/// <summary>
/// Gets the row value for the aggregator as string
/// </summary>
internal String GetRowValueAsString(DataRow tableRow)
{
try
{
if (!tableRow.IsNull(this.AggregatorVariable.VariableName))
{
return(tableRow[this.AggregatorVariable.VariableName].ToString());
}
return(String.Empty);
}
catch (Exception ex)
{
RDFQueryEvents.RaiseSELECTQueryEvaluation(String.Format("Exception intercepted during evaluation of RDFAggregator '{0}' in method GetRowValueAsString: '{1}'", this, ex.Message));
return(String.Empty);
}
}