// New creates a new cayley handle.
func New(mongoURL string, ses *mgo.Session) (*cayley.Handle, error) {
// If the session is not provided, create the Cayley Handle from
// the mongo URL.
if ses == nil {
// Parse the provied mongoURL.
cfg, err := url.Parse(mongoURL)
if err != nil {
return nil, err
}
// Form the Cayley connection options.
opts := parseMongoURL(cfg)
// Create the cayley handle that maintains a connection to the
// Cayley graph database in Mongo.
store, err := cayley.NewGraph("mongo", cfg.Host, opts)
if err != nil {
return store, err
}
return store, nil
}
// If the session is not nil, create the Cayley handle with the
// provided mongo session.
opts := make(map[string]interface{})
opts["session"] = ses
// Create the cayley handle that maintains a connection to the
// Cayley graph database in Mongo.
store, err := cayley.NewGraph("mongo", "", opts)
if err != nil {
return store, err
}
return store, nil
}
func loadGraph(path string) (*cayley.Handle, error) {
*graph.IgnoreDup = true
err := graph.InitQuadStore("leveldb", path, map[string]interface{}{
"ignore_duplicate": true,
})
if err == graph.ErrDatabaseExists {
log.Print(err)
} else if err != nil {
return nil, err
}
return cayley.NewGraph("leveldb", path, nil)
}
func main() {
// File for your new BoltDB. Use path to regular file and not temporary in the real world
tmpfile, err := ioutil.TempFile("", "example")
if err != nil {
log.Fatal(err)
}
defer os.Remove(tmpfile.Name()) // clean up
// Initialize the database
graph.InitQuadStore("bolt", tmpfile.Name(), nil)
// Open and use the database
store, err := cayley.NewGraph("bolt", tmpfile.Name(), nil)
if err != nil {
log.Fatalln(err)
}
store.AddQuad(quad.Make("phrase of the day", "is of course", "Hello BoltDB!", "demo graph"))
// Now we create the path, to get to our data
p := cayley.StartPath(store, quad.String("phrase of the day")).Out(quad.String("is of course"))
// This is more advanced example of the query.
// Simpler equivalent can be found in hello_world example.
// Now we get an iterator for the path and optimize it.
// The second return is if it was optimized, but we don't care for now.
it, _ := p.BuildIterator().Optimize()
// Optimize iterator on quad store level.
// After this step iterators will be replaced with backend-specific ones.
it, _ = store.OptimizeIterator(it)
// remember to cleanup after yourself
defer it.Close()
// While we have items
for it.Next() {
token := it.Result() // get a ref to a node (backend-specific)
value := store.NameOf(token) // get the value in the node (RDF)
nativeValue := quad.NativeOf(value) // convert value to normal Go type
fmt.Println(nativeValue) // print it!
}
if err := it.Err(); err != nil {
log.Fatalln(err)
}
}