[storage] include delete doc method

In this commit we included a delete doc method
that removes a doc by a given index.

Author: Christos Kotsis

db/storage.go

@@ -108,6 +108,21 @@ func (s *Storage) SetName(n string, i int) error {
 	return nil
 }
 
+// DeleteDoc will the document with the given index
+func (s *Storage) DeleteDoc(i int) error {
+	if i > len(s.Data)-1 {
+		return wrapErr(fmt.Errorf(libOutOfIndex), getFn())
+	}
+
+	s.Data = append(s.Data[:i], s.Data[i+1:]...)
+
+	if s.AD == i {
+		s.AD = 0
+	}
+
+	return nil
+}
+
 // Switch will change Active Document (AD) to the given index
 func (s *Storage) Switch(i int) error {
 	if i > len(s.Data)-1 {
@@ -145,7 +160,7 @@ func (s *Storage) SwitchDoc(n string) error {
 }
 
 // ImportDocs for importing documents
-func (s *Storage) ImportDocs(path string) error {
+func (s *Storage) ImportDocs(path string, o ...bool) error {
 	impf, err := ioutil.ReadFile(path)
 	if err != nil {
 		return wrapErr(err, getFn())
@@ -155,6 +170,12 @@ func (s *Storage) ImportDocs(path string) error {
 	var counter int
 	var data interface{}
 
+	if len(o) > 0 {
+		if o[0] {
+			s.Data = nil
+		}
+	}
+
 	data = nil
 	dec := yaml.NewDecoder(bytes.NewReader(impf))
 	for {

docs/examples/kubernetes-labels-update.md

@@ -19,7 +19,12 @@ func main() {
 	if err != nil {
 		logger.Fatal(err)
 	}
-	err = state.ImportDocs("manifests/deployment.yaml")
+
+	// passing true is optional. When we pass it, we instruct the import method
+	// overwrite the content of the db (local/db.yaml). If we do not pass true,
+	// the local/db.yaml file will also have one additional document which is
+	// an empty {} doc that is created during init.
+	err = state.ImportDocs("manifests/deployment.yaml", true)
 	if err != nil {
 		logger.Fatal(err)
 	}