Search package improvements to retrieve documents with text searches from OpenSearch

Related to #12 (closed)

reflection/get.go

+package reflection
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"gitlab.com/uafrica/go-utils/errors"
+)
+
+func Get(v reflect.Value, key string) (reflect.Value, error) {
+	return get("", v, key)
+}
+
+func get(name string, v reflect.Value, key string) (reflect.Value, error) {
+	if key == "" {
+		return v, nil
+	}
+
+	switch v.Kind() {
+	case reflect.Ptr:
+		return get(name, v.Elem(), key)
+
+	case reflect.Struct:
+		if key[0] != '.' {
+			return v, errors.Errorf("get(%s): key=\"%s\" does not start with '.'", name, key)
+		}
+		fieldName := key[1:]
+		remainingKey := ""
+		index := strings.IndexAny(fieldName, ".[")
+		if index > 0 {
+			fieldName = key[1 : index+1]
+			remainingKey = key[index+1:]
+		}
+		t := v.Type()
+		fieldIndex := 0
+		for fieldIndex = 0; fieldIndex < t.NumField(); fieldIndex++ {
+			if strings.SplitN(t.Field(fieldIndex).Tag.Get("json"), ",", 2)[0] == fieldName {
+				break
+			}
+		}
+		if fieldIndex >= t.NumField() {
+			return v, errors.Errorf("%s does not have field %s", name, fieldName)
+		}
+		return get(name+"."+fieldName, v.Field(fieldIndex), remainingKey)
+
+	case reflect.Slice:
+		if !strings.HasPrefix(key, "[]") {
+			return v, errors.Errorf("canot get %s from slice, expecting \"[]\" in the key", key)
+		}
+
+		//make array of results from each item in the slice
+		var result reflect.Value
+		for i := 0; i < v.Len(); i++ {
+			if vv, err := get(fmt.Sprintf("%s[%d]", name, i), v.Index(i), key[2:]); err != nil {
+				return v, errors.Wrapf(err, "failed on %s[%d]", name, i)
+			} else {
+				if !result.IsValid() {
+					result = reflect.MakeSlice(reflect.SliceOf(vv.Type()), 0, v.Len())
+				}
+				result = reflect.Append(result, vv)
+			}
+		}
+		return result, nil
+
+	default:
+	}
+	return v, errors.Errorf("Cannot get %s from %s", key, v.Kind())
+}