Merge pull request #292 from ds--/master

Adds exporting capabilities

internal/dump.go

@@ -0,0 +1,61 @@
+package internal
+
+import (
+	"fmt"
+	"os"
+	"compress/gzip"
+	"path/filepath"
+
+	"github.com/google/cayley/graph"
+	"github.com/google/cayley/exporter"
+)
+
+// Dump the content of the database into a file based
+// on a few different formats
+func Dump(qs graph.QuadStore, outFile, typ string) error {
+	var f *os.File
+	if outFile == "-" {
+		f = os.Stdout
+	} else {
+		var err error
+		f, err = os.Create(outFile)
+		if err != nil {
+			return fmt.Errorf("could not open file %q: %v", outFile, err)
+		}
+		defer f.Close()
+		fmt.Printf("dumping db to file %q\n", outFile)
+	}
+
+	var export *exporter.Exporter
+	if filepath.Ext(outFile) == ".gz" {
+		gzip := gzip.NewWriter(f)
+		defer gzip.Close()
+		export = exporter.NewExporter(gzip, qs)
+	} else {
+		export = exporter.NewExporter(f, qs)
+	}
+
+	//TODO: add possible support for exporting specific queries only
+	switch typ {
+	case "quad":
+		export.ExportQuad()
+	case "json":
+		export.ExportJson()
+	// gml/graphml experimental
+	case "gml":
+		export.ExportGml()
+	case "graphml":
+		export.ExportGraphml()
+	default:
+		return fmt.Errorf("unknown format %q", typ)
+	}
+	
+	if export.Err() != nil {
+		return export.Err()
+	}
+
+        if outFile != "-" {
+		fmt.Printf("%d entries were written\n", export.Count())
+	}
+	return nil
+}