cayleygraph/cayley · error

ErrEmptyPath

ErrEmptyPath

Error message

kv: path to the database must be specified

What it means

ErrEmptyPath is returned by kv backend Create functions when the caller supplies an empty path string. Since kv backends store data on disk (badger, bbolt, leveldb), an empty path would be ambiguous or dangerous, so creation is rejected up front with this sentinel error.

Source

Thrown at graph/kv/quadstore.go:40

	"fmt"
	"os"
	"sync"

	"github.com/cayleygraph/quad"
	"github.com/cayleygraph/quad/pquads"
	"github.com/hidal-go/hidalgo/kv"
	boom "github.com/tylertreat/BoomFilters"

	"github.com/cayleygraph/cayley/graph"
	"github.com/cayleygraph/cayley/graph/proto"
	"github.com/cayleygraph/cayley/graph/refs"
	"github.com/cayleygraph/cayley/internal/lru"
	"github.com/cayleygraph/cayley/query/shape"
)

var (
	ErrNoBucket  = errors.New("kv: no bucket")
	ErrEmptyPath = errors.New("kv: path to the database must be specified")
)

type Registration struct {
	NewFunc      NewFunc
	InitFunc     InitFunc
	IsPersistent bool
}

type InitFunc func(string, graph.Options) (kv.KV, error)
type NewFunc func(string, graph.Options) (kv.KV, error)

func Register(name string, r Registration) {
	graph.RegisterQuadStore(name, graph.QuadStoreRegistration{
		InitFunc: func(addr string, opt graph.Options) error {
			if !r.IsPersistent {
				return nil
			}
			kv, err := r.InitFunc(addr, opt)

View on GitHub (pinned to 81dcd7d73e)

Solutions

1. Set the database path in your configuration (e.g. storage_path in the Cayley config) or pass a non-empty path argument.
2. Load the value from an environment variable or config file and validate it is non-empty before calling Create.
3. In code, check path != "" before invoking the backend registration.

Example fix

// before
kv, err := badgerdb.Create(cfg.DBPath, opts) // DBPath is ""
// after
if cfg.DBPath == "" {
    return errors.New("config: storage path must be set")
}
kv, err := badgerdb.Create(cfg.DBPath, opts)

if path == "" {
    return errors.New("database path must be configured (storage_path)")
}

kv, err := backend.Create(path, opts)
if errors.Is(err, kv.ErrEmptyPath) {
    return fmt.Errorf("configuration error: set storage_path before opening the database")
}

When it happens

Trigger: Calling graph/kv/{badger,bbolt,...}.Create("", opts) or graph.NewInit/open paths that derive the database path from configuration where the path field is missing or empty.

Common situations: Missing 'storage_path' / database path entry in the Cayley config file, constructing options programmatically and forgetting the path, environment variable not set so the path defaults to "".

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• ErrNoBucket
• kv: data version is out of date. Run cayleyupgrade for your
• unknown quad format %q
• iterator already used in query
• HTTP Request needed

AI-assisted analysis of cayleygraph/cayley@81dcd7d73e (2026-09-06). Data as JSON: /api/errors/86a9e8d4f0ad40a6. Report an issue: GitHub.