feat(dump): dumping data from badger.DB into n-djson

cmd/dump.go

@@ -0,0 +1,94 @@
+package cmd
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/dgraph-io/badger/v4"
+	"github.com/spf13/cobra"
+)
+
+type dumpEntry struct {
+	Key      string `json:"key"`
+	Value    string `json:"value"`
+	Encoding string `json:"encoding,omitempty"`
+}
+
+var dumpCmd = &cobra.Command{
+	Use:   "dump [DB]",
+	Short: "Dump all key/value pairs as NDJSON",
+	Args:  cobra.MaximumNArgs(1),
+	RunE:  dump,
+}
+
+func dump(cmd *cobra.Command, args []string) error {
+	store := &Store{}
+	targetDB := "@default"
+	if len(args) == 1 {
+		rawArg := args[0]
+		dbName, err := store.parseDB(rawArg, false)
+		if err != nil {
+			return err
+		}
+		if _, err := store.FindStore(dbName); err != nil {
+			var notFound errNotFound
+			if errors.As(err, &notFound) {
+				return fmt.Errorf("%q does not exist, %s", rawArg, err.Error())
+			}
+			return err
+		}
+		targetDB = "@" + dbName
+	}
+
+	encoding, err := cmd.Flags().GetString("encoding")
+	if err != nil {
+		return err
+	}
+	if encoding != "base64" && encoding != "text" {
+		return fmt.Errorf("unsupported encoding %q", encoding)
+	}
+
+	trans := TransactionArgs{
+		key:      targetDB,
+		readonly: true,
+		sync:     true,
+		transact: func(tx *badger.Txn, k []byte) error {
+			opts := badger.DefaultIteratorOptions
+			opts.PrefetchSize = 64
+			it := tx.NewIterator(opts)
+			defer it.Close()
+			for it.Rewind(); it.Valid(); it.Next() {
+				item := it.Item()
+				key := item.KeyCopy(nil)
+				if err := item.Value(func(v []byte) error {
+					entry := dumpEntry{Key: string(key)}
+					switch encoding {
+					case "base64":
+						entry.Value = base64.StdEncoding.EncodeToString(v)
+						entry.Encoding = "base64"
+					case "text":
+						entry.Value = string(v)
+					}
+					payload, err := json.Marshal(entry)
+					if err != nil {
+						return err
+					}
+					fmt.Fprintln(cmd.OutOrStdout(), string(payload))
+					return nil
+				}); err != nil {
+					return err
+				}
+			}
+			return nil
+		},
+	}
+
+	return store.Transaction(trans)
+}
+
+func init() {
+	dumpCmd.Flags().StringP("encoding", "e", "base64", "value encoding: base64 or text")
+	rootCmd.AddCommand(dumpCmd)
+}