From cc63183b058f6d20f36abfe835b8594c4d1ac448 Mon Sep 17 00:00:00 2001
From: lowgame <128625014+lowgame@users.noreply.github.com>
Date: Sun, 18 Oct 2026 22:01:20 +0300
Subject: [PATCH] fix: bind valid slices after earlier errors

---
 binder.go      | 36 +++++++++++++++++++++---------------
 binder_test.go | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 15 deletions(-)

diff --git a/binder.go b/binder.go
index 7ae3709fa..f5f7a6088 100644
--- a/binder.go
+++ b/binder.go
@@ -575,6 +575,7 @@ func (b *ValueBinder) intsValue(sourceParam string, dest any, valueMustExist boo
 }
 
 func (b *ValueBinder) ints(sourceParam string, values []string, dest any) *ValueBinder {
+	errorsBefore := len(b.errors)
 	switch d := dest.(type) {
 	case *[]int64:
 		tmp := make([]int64, len(values))
@@ -584,7 +585,7 @@ func (b *ValueBinder) ints(sourceParam string, values []string, dest any) *Value
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]int32:
@@ -595,7 +596,7 @@ func (b *ValueBinder) ints(sourceParam string, values []string, dest any) *Value
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]int16:
@@ -606,7 +607,7 @@ func (b *ValueBinder) ints(sourceParam string, values []string, dest any) *Value
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]int8:
@@ -617,7 +618,7 @@ func (b *ValueBinder) ints(sourceParam string, values []string, dest any) *Value
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]int:
@@ -628,7 +629,7 @@ func (b *ValueBinder) ints(sourceParam string, values []string, dest any) *Value
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	}
@@ -803,6 +804,7 @@ func (b *ValueBinder) uintsValue(sourceParam string, dest any, valueMustExist bo
 }
 
 func (b *ValueBinder) uints(sourceParam string, values []string, dest any) *ValueBinder {
+	errorsBefore := len(b.errors)
 	switch d := dest.(type) {
 	case *[]uint64:
 		tmp := make([]uint64, len(values))
@@ -812,7 +814,7 @@ func (b *ValueBinder) uints(sourceParam string, values []string, dest any) *Valu
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]uint32:
@@ -823,7 +825,7 @@ func (b *ValueBinder) uints(sourceParam string, values []string, dest any) *Valu
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]uint16:
@@ -834,7 +836,7 @@ func (b *ValueBinder) uints(sourceParam string, values []string, dest any) *Valu
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]uint8: // byte is alias to uint8
@@ -845,7 +847,7 @@ func (b *ValueBinder) uints(sourceParam string, values []string, dest any) *Valu
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]uint:
@@ -856,7 +858,7 @@ func (b *ValueBinder) uints(sourceParam string, values []string, dest any) *Valu
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	}
@@ -965,6 +967,7 @@ func (b *ValueBinder) boolsValue(sourceParam string, dest *[]bool, valueMustExis
 }
 
 func (b *ValueBinder) bools(sourceParam string, values []string, dest *[]bool) *ValueBinder {
+	errorsBefore := len(b.errors)
 	tmp := make([]bool, len(values))
 	for i, v := range values {
 		b.bool(sourceParam, v, &tmp[i])
@@ -972,7 +975,7 @@ func (b *ValueBinder) bools(sourceParam string, values []string, dest *[]bool) *
 			return b
 		}
 	}
-	if b.errors == nil {
+	if len(b.errors) == errorsBefore {
 		*dest = tmp
 	}
 	return b
@@ -1056,6 +1059,7 @@ func (b *ValueBinder) floatsValue(sourceParam string, dest any, valueMustExist b
 }
 
 func (b *ValueBinder) floats(sourceParam string, values []string, dest any) *ValueBinder {
+	errorsBefore := len(b.errors)
 	switch d := dest.(type) {
 	case *[]float64:
 		tmp := make([]float64, len(values))
@@ -1065,7 +1069,7 @@ func (b *ValueBinder) floats(sourceParam string, values []string, dest any) *Val
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	case *[]float32:
@@ -1076,7 +1080,7 @@ func (b *ValueBinder) floats(sourceParam string, values []string, dest any) *Val
 				return b
 			}
 		}
-		if b.errors == nil {
+		if len(b.errors) == errorsBefore {
 			*d = tmp
 		}
 	}
@@ -1157,6 +1161,7 @@ func (b *ValueBinder) times(sourceParam string, dest *[]time.Time, layout string
 		return b
 	}
 
+	errorsBefore := len(b.errors)
 	tmp := make([]time.Time, len(values))
 	for i, v := range values {
 		t, err := time.Parse(layout, v)
@@ -1169,7 +1174,7 @@ func (b *ValueBinder) times(sourceParam string, dest *[]time.Time, layout string
 		}
 		tmp[i] = t
 	}
-	if b.errors == nil {
+	if len(b.errors) == errorsBefore {
 		*dest = tmp
 	}
 	return b
@@ -1232,6 +1237,7 @@ func (b *ValueBinder) durationsValue(sourceParam string, dest *[]time.Duration,
 }
 
 func (b *ValueBinder) durations(sourceParam string, values []string, dest *[]time.Duration) *ValueBinder {
+	errorsBefore := len(b.errors)
 	tmp := make([]time.Duration, len(values))
 	for i, v := range values {
 		t, err := time.ParseDuration(v)
@@ -1244,7 +1250,7 @@ func (b *ValueBinder) durations(sourceParam string, values []string, dest *[]tim
 		}
 		tmp[i] = t
 	}
-	if b.errors == nil {
+	if len(b.errors) == errorsBefore {
 		*dest = tmp
 	}
 	return b
diff --git a/binder_test.go b/binder_test.go
index 8eced8208..01f047baf 100644
--- a/binder_test.go
+++ b/binder_test.go
@@ -671,6 +671,38 @@ func TestValueBinder_Int_errorMessage(t *testing.T) {
 	assert.EqualError(t, errs[1], `code=400, message=failed to bind field value to uint, err=strconv.ParseUint: parsing "nope": invalid syntax, field=param`)
 }
 
+func TestValueBinder_FailFastFalseBindsValidSlicesAfterError(t *testing.T) {
+	c := createTestContext("/?bad=nope&ints=1&ints=2&uints=3&uints=4&bools=true&bools=false&floats=1.5&floats=2.5&times=2024-01-02&times=2024-01-03&durations=1s&durations=2s", nil, nil)
+
+	var bad int
+	ints := []int{99}
+	uints := []uint{99}
+	bools := []bool{false}
+	floats := []float64{99}
+	times := []time.Time{{}}
+	durations := []time.Duration{99}
+	errs := QueryParamsBinder(c).FailFast(false).
+		Int("bad", &bad).
+		Ints("ints", &ints).
+		Uints("uints", &uints).
+		Bools("bools", &bools).
+		Float64s("floats", &floats).
+		Times("times", &times, time.DateOnly).
+		Durations("durations", &durations).
+		BindErrors()
+
+	assert.Len(t, errs, 1)
+	assert.Equal(t, []int{1, 2}, ints)
+	assert.Equal(t, []uint{3, 4}, uints)
+	assert.Equal(t, []bool{true, false}, bools)
+	assert.Equal(t, []float64{1.5, 2.5}, floats)
+	assert.Equal(t, []time.Time{
+		time.Date(2024, time.January, 2, 0, 0, 0, 0, time.UTC),
+		time.Date(2024, time.January, 3, 0, 0, 0, 0, time.UTC),
+	}, times)
+	assert.Equal(t, []time.Duration{time.Second, 2 * time.Second}, durations)
+}
+
 func TestValueBinder_Uint64_uintValue(t *testing.T) {
 	var testCases = []struct {
 		name            string