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Overwrite struct's field with corresponding map's key that is intended to be zero #85

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merged 2 commits into from
Jan 23, 2019
Merged

Overwrite struct's field with corresponding map's key that is intended to be zero #85

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d581347
fix #84
requilence Jun 15, 2018
f01cd5a
tests for #84
requilence Jun 15, 2018
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82 changes: 82 additions & 0 deletions issue84_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,82 @@
package mergo

import (
"testing"
)

type DstStructIssue84 struct {
A int
B int
C int
}

type DstNestedStructIssue84 struct {
A struct {
A int
B int
C int
}
B int
C int
}

func TestIssue84MergeMapWithNilValueToStructWithOverride(t *testing.T) {
p1 := DstStructIssue84{
A: 0, B: 1, C: 2,
}
p2 := map[string]interface{}{
"A": 3, "B": 4, "C": 0,
}
if err := Map(&p1, p2, WithOverride); err != nil {
t.Fatalf("Error during the merge: %v", err)
}
if p1.C != 0 {
t.Error("C field should become '0'")
}
}

func TestIssue84MergeMapWithoutKeyExistsToStructWithOverride(t *testing.T) {
p1 := DstStructIssue84{
A: 0, B: 1, C: 2,
}
p2 := map[string]interface{}{
"A": 3, "B": 4,
}
if err := Map(&p1, p2, WithOverride); err != nil {
t.Fatalf("Error during the merge: %v", err)
}
if p1.C != 2 {
t.Error("C field should be '2'")
}
}

func TestIssue84MergeNestedMapWithNilValueToStructWithOverride(t *testing.T) {
p1 := DstNestedStructIssue84{
A: struct {
A int
B int
C int
}{A: 1, B: 2, C: 0},
B: 0,
C: 2,
}
p2 := map[string]interface{}{
"A": map[string]interface{}{
"A": 0, "B": 0, "C": 5,
}, "B": 4, "C": 0,
}
if err := Map(&p1, p2, WithOverride); err != nil {
t.Fatalf("Error during the merge: %v", err)
}
if p1.B != 4 {
t.Error("A.C field should become '4'")
}

if p1.A.C != 5 {
t.Error("A.C field should become '5'")
}

if p1.A.B != 0 || p1.A.A != 0 {
t.Error("A.A and A.B field should become '0'")
}
}
1 change: 1 addition & 0 deletions map.go
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,7 @@ func deepMap(dst, src reflect.Value, visited map[uintptr]*visit, depth int, conf
case reflect.Struct:
srcMap := src.Interface().(map[string]interface{})
for key := range srcMap {
config.overwriteWithEmptyValue = true
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@liggitt liggitt Apr 15, 2021 •
edited
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if the continue or return cases are hit below without calling deepMerge (which would have reset to false), this results in mutating config and setting overwriteWithEmptyValue=true that can affect other calls to deepMerge

srcValue := srcMap[key]
fieldName := changeInitialCase(key, unicode.ToUpper)
dstElement := dst.FieldByName(fieldName)
Expand Down
17 changes: 10 additions & 7 deletions merge.go
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Expand Up @@ -25,9 +25,10 @@ func hasExportedField(dst reflect.Value) (exported bool) {
}

type Config struct {
Overwrite bool
AppendSlice bool
Transformers Transformers
Overwrite bool
AppendSlice bool
Transformers Transformers
overwriteWithEmptyValue bool
}

type Transformers interface {
Expand All @@ -39,6 +40,8 @@ type Transformers interface {
// short circuiting on recursive types.
func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, config *Config) (err error) {
overwrite := config.Overwrite
overwriteWithEmptySrc := config.overwriteWithEmptyValue
config.overwriteWithEmptyValue = false

if !src.IsValid() {
return
Expand Down Expand Up @@ -73,7 +76,7 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, co
}
}
} else {
if dst.CanSet() && !isEmptyValue(src) && (overwrite || isEmptyValue(dst)) {
if dst.CanSet() && (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst)) {
dst.Set(src)
}
}
Expand Down Expand Up @@ -124,7 +127,7 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, co
dstSlice = reflect.ValueOf(dstElement.Interface())
}

if !isEmptyValue(src) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
if (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
dstSlice = srcSlice
} else if config.AppendSlice {
dstSlice = reflect.AppendSlice(dstSlice, srcSlice)
Expand All @@ -147,7 +150,7 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, co
if !dst.CanSet() {
break
}
if !isEmptyValue(src) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
if (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
dst.Set(src)
} else if config.AppendSlice {
dst.Set(reflect.AppendSlice(dst, src))
Expand Down Expand Up @@ -184,7 +187,7 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, co
return
}
default:
if dst.CanSet() && !isEmptyValue(src) && (overwrite || isEmptyValue(dst)) {
if dst.CanSet() && (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst)) {
dst.Set(src)
}
}
Expand Down