Update storage to new object format

storage/operator/modify.go

@@ -0,0 +1,59 @@
+package operator
+
+import (
+	"fmt"
+
+	"go.mongodb.org/mongo-driver/bson"
+)
+
+type Unset string
+
+func (u Unset) MarshalBSON() ([]byte, error) {
+	return opMarshal("$unset", string(u), "")
+}
+
+type PopIf struct {
+	Key    string
+	Filter interface{}
+}
+
+func (pi PopIf) MarshalBSON() ([]byte, error) {
+	return opMarshal("$pull", pi.Key, pi.Filter)
+}
+
+type Set struct {
+	Key   string
+	Value interface{}
+}
+
+func (s Set) MarshalBSON() ([]byte, error) {
+	return opMarshal("$set", s.Key, s.Value)
+}
+
+type Push struct {
+	Key   string
+	Value interface{}
+}
+
+func (p Push) MarshalBSON() ([]byte, error) {
+	return opMarshal("$push", p.Key, p.Value)
+}
+
+func opMarshal(op, key string, value interface{}) ([]byte, error) {
+	marshalable := opMarshalable(op, key, value)
+	if len(marshalable) == 0 {
+		return nil, fmt.Errorf("failed marshalling op")
+	}
+	return bson.Marshal(marshalable)
+}
+
+func opMarshalable(op, key string, value interface{}) map[string]map[string]interface{} {
+	if len(key) == 0 {
+		return nil
+	}
+	return map[string]map[string]interface{}{
+		op: map[string]interface{}{
+			key: value,
+		},
+	}
+}