From f675819c38683071f832d7266fc651e55794e033 Mon Sep 17 00:00:00 2001
From: Christian Theilemann <christian.theilemann@getcruise.com>
Date: Mon, 20 Jan 2020 13:03:22 -0800
Subject: [PATCH] introduce EachUntilFirstError for validating slices and maps
 with lots of items

---
 each_until_first_error.go      | 84 ++++++++++++++++++++++++++++++++++
 each_until_first_error_test.go | 39 ++++++++++++++++
 2 files changed, 123 insertions(+)
 create mode 100644 each_until_first_error.go
 create mode 100644 each_until_first_error_test.go

diff --git a/each_until_first_error.go b/each_until_first_error.go
new file mode 100644
index 0000000..a00b339
--- /dev/null
+++ b/each_until_first_error.go
@@ -0,0 +1,84 @@
+// Copyright 2016 Qiang Xue. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package validation
+
+import (
+	"errors"
+	"reflect"
+	"strconv"
+)
+
+// EachUntilFirstError is the same as Each but stops early once the first item with a validation error was encountered.
+// Use this instead of Each for array's or maps that may potentially contain ten-thousands of erroneous items and
+// you want to avoid returning ten-thousands of validation errors (for memory and cpu reasons).
+func EachUntilFirstError(rules ...Rule) EachUntilFirstErrorRule {
+	return EachUntilFirstErrorRule{
+		rules: rules,
+	}
+}
+
+// EachUntilFirstErrorRule is the same as EachRule but stops early once the first item with a validation error was encountered.
+// Use this instead of EachRule for array's or maps that may potentially contain ten-thousands of erroneous items and
+// you want to avoid returning ten-thousands of validation errors (for memory and cpu reasons).
+type EachUntilFirstErrorRule struct {
+	rules []Rule
+	limit int
+}
+
+// Validate loops through the given iterable and calls the Ozzo Validate() method for each value.
+func (r EachUntilFirstErrorRule) Validate(value interface{}) error {
+	errs := Errors{}
+
+	v := reflect.ValueOf(value)
+	switch v.Kind() {
+	case reflect.Map:
+		for _, k := range v.MapKeys() {
+			val := r.getInterface(v.MapIndex(k))
+			if err := Validate(val, r.rules...); err != nil {
+				errs[r.getString(k)] = err
+				break
+			}
+		}
+	case reflect.Slice, reflect.Array:
+		for i := 0; i < v.Len(); i++ {
+			val := r.getInterface(v.Index(i))
+			if err := Validate(val, r.rules...); err != nil {
+				errs[strconv.Itoa(i)] = err
+				break
+			}
+		}
+	default:
+		return errors.New("must be an iterable (map, slice or array)")
+	}
+
+	if len(errs) > 0 {
+		return errs
+	}
+	return nil
+}
+
+func (r EachUntilFirstErrorRule) getInterface(value reflect.Value) interface{} {
+	switch value.Kind() {
+	case reflect.Ptr, reflect.Interface:
+		if value.IsNil() {
+			return nil
+		}
+		return value.Elem().Interface()
+	default:
+		return value.Interface()
+	}
+}
+
+func (r EachUntilFirstErrorRule) getString(value reflect.Value) string {
+	switch value.Kind() {
+	case reflect.Ptr, reflect.Interface:
+		if value.IsNil() {
+			return ""
+		}
+		return value.Elem().String()
+	default:
+		return value.String()
+	}
+}
diff --git a/each_until_first_error_test.go b/each_until_first_error_test.go
new file mode 100644
index 0000000..4a17803
--- /dev/null
+++ b/each_until_first_error_test.go
@@ -0,0 +1,39 @@
+package validation
+
+import (
+	"testing"
+)
+
+func TestEachUntilFirstError(t *testing.T) {
+	var a *int
+	var f = func(v string) string { return v }
+	var c0 chan int
+	c1 := make(chan int)
+
+	tests := []struct {
+		tag   string
+		value interface{}
+		err   string
+	}{
+		{"t1", nil, "must be an iterable (map, slice or array)"},
+		{"t2", map[string]string{}, ""},
+		{"t3", map[string]string{"key1": "value1", "key2": "value2"}, ""},
+		{"t4", map[string]string{"key1": "", "key2": "value2", "key3": ""}, "key1: cannot be blank."},
+		{"t5", map[string]map[string]string{"key1": {"key1.1": "value1"}, "key2": {"key2.1": "value1"}}, ""},
+		{"t6", map[string]map[string]string{"": nil}, ": cannot be blank."},
+		{"t7", map[interface{}]interface{}{}, ""},
+		{"t8", map[interface{}]interface{}{"key1": struct{ foo string }{"foo"}}, ""},
+		{"t9", map[interface{}]interface{}{nil: "", "": "", "key1": nil}, ": cannot be blank."},
+		{"t10", []string{"value1", "value2", "value3"}, ""},
+		{"t11", []string{"", "value2", ""}, "0: cannot be blank."},
+		{"t12", []interface{}{struct{ foo string }{"foo"}}, ""},
+		{"t13", []interface{}{nil, a}, "0: cannot be blank."},
+		{"t14", []interface{}{c0, c1, f}, "0: cannot be blank."},
+	}
+
+	for _, test := range tests {
+		r := EachUntilFirstError(Required)
+		err := r.Validate(test.value)
+		assertError(t, test.err, err, test.tag)
+	}
+}