From dc8463a290fa716af4298c7f3e94e4a11dbd44b6 Mon Sep 17 00:00:00 2001
From: ston1th <ston1th@giftfish.de>
Date: Mon, 13 Nov 2017 19:29:43 +0100
Subject: [PATCH] made asc sorting optional and added regression tests

---
 README.md          |  1 +
 filter.go          | 26 +++++++++++---------------
 helper.go          |  6 ++++--
 regression_test.go | 20 ++++++++++++++++++++
 4 files changed, 36 insertions(+), 17 deletions(-)
 create mode 100644 regression_test.go

diff --git a/README.md b/README.md
index 6a2b248..c19fbb5 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,7 @@ Bool does not support the wildcard operator, only the literal strings `true` and
 The sort statement consists of the literal string `sort`, the field name (nesting like above is supported) and the literal strings `asc` or `desc`.
 
 ```
+sort:<struct field> (short version for asc)
 sort:<struct field>:asc
 sort:<struct field>:desc
 sort:<struct field>.<struct field>:desc
diff --git a/filter.go b/filter.go
index 0025946..124fb9d 100644
--- a/filter.go
+++ b/filter.go
@@ -115,27 +115,23 @@ func NewQuery(s string) (q *Query, err error) {
 		}
 		if !q.s.enabled {
 			s := strings.SplitN(v, ":", 3)
-			if len(s) == 3 {
-				if s[0] == "sort" {
+			if s[0] == "sort" && len(s) >= 2 {
+				q.s.fields = strings.Split(s[1], ".")
+				if err = checkFields(q.s.fields, v); err != nil {
+					return
+				}
+				if len(s) == 3 {
 					switch s[2] {
-					case asc, desc:
-						q.s.fields = strings.Split(s[1], ".")
-						if err = checkFields(q.s.fields, v); err != nil {
-							return
-						}
-						if len(q.s.fields) > 0 {
-							if s[2] == desc {
-								q.s.desc = true
-							}
-							q.s.enabled = true
-						}
-						continue
+					case desc:
+						q.s.desc = true
+					case asc:
 					default:
 						err = newErr("invalid sort: " + v)
 						return
 					}
-
 				}
+				q.s.enabled = true
+				continue
 			}
 		}
 		m := strings.SplitN(v, ":", 2)
diff --git a/helper.go b/helper.go
index 4bd92a7..2be87f2 100644
--- a/helper.go
+++ b/helper.go
@@ -1,7 +1,6 @@
 package filter
 
 import (
-	"errors"
 	"reflect"
 	"strconv"
 	"strings"
@@ -13,9 +12,12 @@ const (
 )
 
 func checkFields(s []string, val string) error {
+	if len(s) == 0 {
+		return newErr("invalid field: " + val)
+	}
 	for _, v := range s {
 		if v == "" {
-			return errors.New("invalid subfield: " + val)
+			return newErr("invalid subfield: " + val)
 		}
 	}
 	return nil
diff --git a/regression_test.go b/regression_test.go
new file mode 100644
index 0000000..ae46655
--- /dev/null
+++ b/regression_test.go
@@ -0,0 +1,20 @@
+package filter
+
+import "testing"
+
+func TestRegression(t *testing.T) {
+	data := []string{
+		"sort::asc",
+		"Int.:",
+		"String.:",
+		"sort::desc",
+		".:",
+		"sort:.0:asc",
+	}
+	for _, v := range data {
+		_, err := NewQuery(v)
+		if err == nil {
+			t.Errorf("regression: '%s'", v)
+		}
+	}
+}