当我执行插入查询RDF4J时如何获取UpdateExpr

Question

插入查询的问题，无法解析简单的语句

示例：查询：

PREFIX dc: <http://purl.org/dc/elements/1.1/>
INSERT DATA 
{
    <http://example/book1> dc:title "A new book";
                           dc:creator "A.N.Other" .
}

结果：

PREFIX dc: <http://purl.org/dc/elements/1.1/> 
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
PREFIX sesame: <http://www.openrdf.org/schema/sesame#> 
PREFIX owl: <http://www.w3.org/2002/07/owl#> 
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> 
PREFIX fn: <http://www.w3.org/2005/xpath-functions#> 
 <http://example/book1> dc:title "A new book" ; dc:creator "A.N.Other" .

但是，如果我解决一些更困难的问题，一切都很好

查询：

PREFIX dc:  <http://purl.org/dc/elements/1.1/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>

INSERT 
  { GRAPH <http://example/bookStore2> { ?book ?p ?v } }
WHERE
  { GRAPH  <http://example/bookStore>
       { ?book dc:date ?date .
         FILTER ( ?date > "1970-01-01T00:00:00-02:00"^^xsd:dateTime )
         ?book ?p ?v
  } }

结果：

StatementPattern FROM NAMED CONTEXT
   Var (name=book)
   Var (name=p)
   Var (name=v)
   Var (name=_const_f1165b11_uri, value=http://example/bookStore2, anonymous)

Modify
   StatementPattern FROM NAMED CONTEXT
      Var (name=book)
      Var (name=p)
      Var (name=v)
      Var (name=_const_f1165b11_uri, value=http://example/bookStore2, anonymous)
   Filter
      Compare (>)
         Var (name=date)
         ValueConstant (value="1970-01-01T00:00:00-02:00"^^<http://www.w3.org/2001/XMLSchema#dateTime>)
      Join
         StatementPattern FROM NAMED CONTEXT
            Var (name=book)
            Var (name=_const_9b277d39_uri, value=http://purl.org/dc/elements/1.1/date, anonymous)
            Var (name=date)
            Var (name=_const_39534d41_uri, value=http://example/bookStore, anonymous)
         StatementPattern FROM NAMED CONTEXT
            Var (name=book)
            Var (name=p)
            Var (name=v)
            Var (name=_const_39534d41_uri, value=http://example/bookStore, anonymous)

我需要得到第一种情况。我究竟做错了什么？

用于执行这些查询的Java代码：

String query = ...
SPARQLParser parser = new SPARQLParser();
ParsedUpdate q2 = parser.parseUpdate(query, null);
Iterator var2 = q2.getUpdateExprs().iterator();
UpdateExpr updateExpr = (UpdateExpr)var2.next();
System.out.println(updateExpr);

Answer 1

如注释中所示，INSERT DATA SPARQL更新的数据块在内部存储为（未解析的）字符串。如果您希望进一步处理它，您有几个选择。

一种选择是实际上只是执行更新，例如针对临时/空的内存存储，然后只检索该存储中的语句：

 String update = "INSERT DATA { .... }";
 Repository tempRep = new SailRepository(new MemoryStore());
 tempRep.init();
 try(RepositoryConnection conn = tempRep.getConnection()) {
     conn.prepareUpdate(update).execute());
     Model statements = QueryResults.asModel(conn.getStatements(null, null, null));
 }

另一个可能更具可扩展性的选项是将数据块提取为字符串并将其传递给解析器。 SPARQLUpdateDataBlockParser专门用于此目的：

InsertData insertDataExpr = (InsertData)updateExpr;

RDFParser parser = new SPARQLUpdateDataBlockParser();
StatementCollector handler = new StatementCollector();
parser.setRDFHandler(handler);

parser.parse(new StringReader(insertDataExpr.getDataBlock()), "");

Collection<Statement> stmts = handler.getStatements();