Add a GetString helper for simple string annotations. Add tests which call Get and GetString on annotations objects (#1118)

api/models/annotations.go

@@ -160,6 +160,18 @@ func (m Annotations) Get(key string) ([]byte, bool) {
 	return nil, false
 }
 
+// GetString returns a string value if the annotation value is a string, otherwise an error
+func (m Annotations) GetString(key string) (string, error) {
+	if v, ok := m[key]; ok {
+		var s string
+		if err := json.Unmarshal([]byte(*v), &s); err != nil {
+			return "", err
+		}
+		return s, nil
+	}
+	return "", errors.New("Annotation not found")
+}
+
 // Without returns a new annotations object with a value excluded
 func (m Annotations) Without(key string) Annotations {
 	nuVal := m.clone()

api/models/annotations_test.go

@@ -259,3 +259,45 @@ func TestMergeAnnotations(t *testing.T) {
 	}
 
 }
+
+func TestGetAnnotations(t *testing.T) {
+	annotations := EmptyAnnotations()
+	annotations, err := annotations.With("string-annotation", "string-value")
+	if err != nil {
+		t.Fatal("Cannot add string annotation")
+	}
+	annotations, err = annotations.With("array-annotation", []string{"string-1", "string-2"})
+	if err != nil {
+		t.Fatal("Cannot add array annotation")
+	}
+	strAnnotation, ok := annotations.Get("string-annotation")
+	if !ok {
+		t.Error("Cannot get string annotation")
+	}
+	expected := "\"string-value\""
+	if string(strAnnotation) != expected {
+		t.Errorf("Got unexpected value for string annotation. Got: %s Expected %s", strAnnotation, expected)
+	}
+	arrAnnotation, ok := annotations.Get("array-annotation")
+	if !ok {
+		t.Error("Cannot get array annotation")
+	}
+	expected = "[\"string-1\",\"string-2\"]"
+	if string(arrAnnotation) != expected {
+		t.Errorf("Got unexpected value for array annotation. Got: %s Expected %s", strAnnotation, expected)
+	}
+
+	stringAnnotation, err := annotations.GetString("string-annotation")
+	if err != nil {
+		t.Fatalf("Error decoding string annotation: %v", err)
+	}
+	expected = "string-value"
+	if stringAnnotation != expected {
+		t.Errorf("Got unexpected decoded value for string annotation. Got: %s Expected %s", strAnnotation, expected)
+	}
+
+	_, err = annotations.GetString("array-annotation")
+	if err == nil {
+		t.Error("Expected error trying to retrieve a string value for array annotation")
+	}
+}