//ExecuteQueryToFormattedString executes a query and serializes the results to a string in the format provided
func (model *Model) ExecuteQueryToFormattedString(query *Query, format string) (string, error) {
var librdf_query *C.librdf_query
cQueryString := C.CString(query.queryString)
if cQueryString != nil {
defer C.free(unsafe.Pointer(cQueryString))
}
cName := C.CString(query.name)
if cName != nil {
defer C.free(unsafe.Pointer(cName))
}
cFormat := C.CString(format)
if cFormat != nil {
defer C.free(unsafe.Pointer(cFormat))
}
librdf_query = C.librdf_new_query(query.world.librdf_world, (*C.char)(unsafe.Pointer(cName)), nil, (*C.uchar)(unsafe.Pointer(cQueryString)), nil)
if librdf_query == nil {
return "", errors.New("Unable to create query for execution")
}
results := C.librdf_model_query_execute(model.librdf_model, librdf_query)
if results == nil {
return "", errors.New("Failed to execute query")
}
var cFormattedString *C.uchar
isBindings := C.librdf_query_results_is_bindings(results)
isBoolean := C.librdf_query_results_is_boolean(results)
if isBindings == 0 || isBoolean == 0 {
cFormattedString = C.librdf_query_results_to_string2(results, (*C.char)(unsafe.Pointer(cFormat)), nil, nil, nil)
} else {
var serializer *C.librdf_serializer
if serializer = C.librdf_new_serializer(query.world.librdf_world, (*C.char)(unsafe.Pointer(cFormat)), nil, nil); serializer == nil {
return "", errors.New("Failed to build serializer")
}
defer C.librdf_free_serializer(serializer)
var stream *C.librdf_stream
if stream = C.librdf_query_results_as_stream(results); stream == nil {
return "", errors.New("Failed to build stream from results")
}
defer C.librdf_free_stream(stream)
cFormattedString = C.librdf_serializer_serialize_stream_to_string(serializer, nil, stream)
}
if cFormattedString == nil {
return "", errors.New("Failed to build formatted string from results")
}
defer C.free(unsafe.Pointer(cFormattedString))
formattedString := C.GoString((*C.char)(unsafe.Pointer(cFormattedString)))
return formattedString, nil
}
//ExecuteQueryToResultsChannel executes the given query and returns a channel used to read the results
func (model *Model) ExecuteQueryToResultsChannel(query *Query, bufferSize int) (chan *QueryResultItem, error) {
var err error = nil
chanQueryResultItem := make(chan *QueryResultItem, bufferSize)
cQueryString := C.CString(query.queryString)
if cQueryString != nil {
defer C.free(unsafe.Pointer(cQueryString))
}
cName := C.CString(query.name)
if cName != nil {
defer C.free(unsafe.Pointer(cName))
}
librdf_query := C.librdf_new_query(query.world.librdf_world, (*C.char)(unsafe.Pointer(cName)), nil, (*C.uchar)(unsafe.Pointer(cQueryString)), nil)
if librdf_query == nil {
return nil, errors.New("Failed to create new query")
}
results := C.librdf_model_query_execute(model.librdf_model, librdf_query)
if results == nil {
err = errors.New("Error executing query")
}
if C.librdf_query_results_finished(results) != 0 {
return nil, errors.New("Query returned no results")
}
go func() {
for C.librdf_query_results_finished(results) == 0 {
item := new(QueryResultItem)
cBindingCount := C.librdf_query_results_get_bindings_count(results)
bindingCount := int(cBindingCount)
if bindingCount == 0 {
continue
}
item.NameNodePairs = make([]NameNodePair, bindingCount, bindingCount)
for i := 0; i < bindingCount; i++ {
cName := C.librdf_query_results_get_binding_name(results, C.int(i))
librdf_node := C.librdf_query_results_get_binding_value(results, C.int(i))
item.NameNodePairs[i].Name = C.GoString(cName)
node := new(Node)
node.world = query.world
node.librdf_node = librdf_node
item.NameNodePairs[i].Node = node
}
chanQueryResultItem <- item
C.librdf_query_results_next(results)
}
close(chanQueryResultItem)
}()
return chanQueryResultItem, err
}