Question

我正在使用rdfdotnet库查询rdf文件

这是我的代码

//Define your Graph here - it may be better to use a QueryableGraph if you plan
//on making lots of Queries against this Graph as that is marginally more performant
IGraph g = new Graph();

//Load some data into your Graph using the LoadFromFile() extension method
g.LoadFromFile("C:/Users/admin/Desktop/current/Semantic/test.rdf");

//Use the extension method ExecuteQuery() to make the query against the Graph
try
{
    String q = " Prefix u:<http://localhost:49682/Semantic/test.rdf> SELECT * WHERE {?x1 u:age ?x2}";
        Object results = g.ExecuteQuery(q);

        if (results is SparqlResultSet)
        {
            //SELECT/ASK queries give a SparqlResultSet
            SparqlResultSet rset = (SparqlResultSet)results;
            foreach (SparqlResult r in rset)
            {
                //Do whatever you want with each Result
            }
        }
        else if (results is IGraph)
        {
            //CONSTRUCT/DESCRIBE queries give a IGraph
            IGraph resGraph = (IGraph)results;
            foreach (Triple t in resGraph.Triples)
            {
                //Do whatever you want with each Triple
            }
        }
        else
        {
            //If you don't get a SparqlResutlSet or IGraph something went wrong 
            //but didn't throw an exception so you should handle it here
            Console.WriteLine("ERROR");
        }
    }
    catch (VDS.RDF.Query.RdfQueryException queryEx)
    {
        //There was an error executing the query so handle it here
        Console.WriteLine(queryEx.Message);
    }

执行查询时出错

[第1行第10列到第1行第52列的UriToken]预期在查询中跟随PREFIX谓词的前缀令牌

Answer 1

您使用的是哪个版本的库？

旧版本有一个错误，在你的情况u:中，前缀之间必须有空格（在你的情况下是<http://localhost:49682/Semantic/test.rdf> - 和名称空间URI}

如果您使用最新版本的库（0.5.1），则不会再出现此问题

修改

这是修复版本0.5.0（请参阅问题CORE-88），因此如果您看到此错误，则至少有两个版本落后，因为我已经回答了升级应解决问题。

查询RDFDOTNET中的RDF文件

1 个答案: