Add Modify() and GetItem() to interface and badger store

badger.go

@@ -39,12 +39,48 @@ func (b badgerStore) Get(key string, out interface{}) error {
 	})
 }
 
+func (b badgerStore) GetItem(key string) (*Item, error) {
+	out := &Item{}
+	err := b.db.View(func(txn *badger.Txn) error {
+		item, err := txn.Get([]byte(key))
+		if err != nil {
+			return err
+		}
+
+		key := string(item.KeyCopy(nil))
+		data, err := item.ValueCopy(nil)
+		if err != nil {
+			return err
+		}
+
+		out.Key = key
+		out.Data = data
+
+		return nil
+	})
+	return out, err
+}
+
 func (b badgerStore) Delete(key string) error {
 	return b.db.Update(func(txn *badger.Txn) error {
 		return txn.Delete([]byte(key))
 	})
 }
 
+func (b badgerStore) Modify(key string, modify ModifyFunc) error {
+	item, err := b.GetItem(key)
+	if err != nil {
+		return err
+	}
+
+	newVal, err := modify(item)
+	if err != nil {
+		return err
+	}
+
+	return b.Set(key, newVal)
+}
+
 func (b badgerStore) Iter() Iter {
 	out := make(chan *Item, 10)
 	go func() {
@@ -90,10 +126,18 @@ func (b badgerBucket) Get(key string, out interface{}) error {
 	return b.store.Get(b.name+"\u001f"+key, out)
 }
 
+func (b badgerBucket) GetItem(key string) (*Item, error) {
+	return b.store.GetItem(b.name + "\u001f" + key)
+}
+
 func (b badgerBucket) Delete(key string) error {
 	return b.store.Delete(b.name + "\u001f" + key)
 }
 
+func (b badgerBucket) Modify(key string, modify ModifyFunc) error {
+	return b.store.Modify(b.name+"\u001f"+key, modify)
+}
+
 func (b badgerBucket) Iter() Iter {
 	out := make(chan *Item, 10)
 	go func() {

main.go

@@ -8,7 +8,12 @@ type Store interface {
 	Set(key string, val interface{}) error
 	// Get places a value at a key into val
 	Get(key string, val interface{}) error
-	Delete(key string) error
+	// GetItem gets an item from the store
+	GetItem(string) (*Item, error)
+	// Delete deletes a value from the store
+	Delete(string) error
+	// Modify allows editing of a value in the store
+	Modify(string, ModifyFunc) error
 	// Bucket returns a bucket with the specified name
 	Bucket(name string) Bucket
 	// Iter returns an iterator
@@ -23,11 +28,18 @@ type Bucket interface {
 	Set(string, interface{}) error
 	// Get places a value at a key in the bucket into val
 	Get(string, interface{}) error
+	// GetItem gets an item from the store
+	GetItem(string) (*Item, error)
+	// Delete deletes a value from the bucket
 	Delete(key string) error
+	// Modify allows editing of a value in the bucket
+	Modify(string, ModifyFunc) error
 	// Iter returns an iterator for the bucket
 	Iter() Iter
 }
 
+type ModifyFunc func(*Item) (interface{}, error)
+
 // Item represents an iterator item
 type Item struct {
 	Key  string