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Dereference multiple pointers when decoding to maps #348

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Dereference multiple pointers when decoding to maps #348

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0d2538a
test: add failing test for GH-347
sagikazarmark Dec 8, 2023
8882141
fix: support multiple levels of indirection when decoding to maps
sagikazarmark Dec 8, 2023
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125 changes: 65 additions & 60 deletions mapstructure.go
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Original file line number Diff line number Diff line change
Expand Up @@ -9,84 +9,84 @@
//
// The simplest function to start with is Decode.
//
// Field Tags
// # Field Tags
//
// When decoding to a struct, mapstructure will use the field name by
// default to perform the mapping. For example, if a struct has a field
// "Username" then mapstructure will look for a key in the source value
// of "username" (case insensitive).
//
// type User struct {
// Username string
// }
// type User struct {
// Username string
// }
//
// You can change the behavior of mapstructure by using struct tags.
// The default struct tag that mapstructure looks for is "mapstructure"
// but you can customize it using DecoderConfig.
//
// Renaming Fields
// # Renaming Fields
//
// To rename the key that mapstructure looks for, use the "mapstructure"
// tag and set a value directly. For example, to change the "username" example
// above to "user":
//
// type User struct {
// Username string `mapstructure:"user"`
// }
// type User struct {
// Username string `mapstructure:"user"`
// }
//
// Embedded Structs and Squashing
// # Embedded Structs and Squashing
//
// Embedded structs are treated as if they're another field with that name.
// By default, the two structs below are equivalent when decoding with
// mapstructure:
//
// type Person struct {
// Name string
// }
// type Person struct {
// Name string
// }
//
// type Friend struct {
// Person
// }
// type Friend struct {
// Person
// }
//
// type Friend struct {
// Person Person
// }
// type Friend struct {
// Person Person
// }
//
// This would require an input that looks like below:
//
// map[string]interface{}{
// "person": map[string]interface{}{"name": "alice"},
// }
// map[string]interface{}{
// "person": map[string]interface{}{"name": "alice"},
// }
//
// If your "person" value is NOT nested, then you can append ",squash" to
// your tag value and mapstructure will treat it as if the embedded struct
// were part of the struct directly. Example:
//
// type Friend struct {
// Person `mapstructure:",squash"`
// }
// type Friend struct {
// Person `mapstructure:",squash"`
// }
//
// Now the following input would be accepted:
//
// map[string]interface{}{
// "name": "alice",
// }
// map[string]interface{}{
// "name": "alice",
// }
//
// When decoding from a struct to a map, the squash tag squashes the struct
// fields into a single map. Using the example structs from above:
//
// Friend{Person: Person{Name: "alice"}}
// Friend{Person: Person{Name: "alice"}}
//
// Will be decoded into a map:
//
// map[string]interface{}{
// "name": "alice",
// }
// map[string]interface{}{
// "name": "alice",
// }
//
// DecoderConfig has a field that changes the behavior of mapstructure
// to always squash embedded structs.
//
// Remainder Values
// # Remainder Values
//
// If there are any unmapped keys in the source value, mapstructure by
// default will silently ignore them. You can error by setting ErrorUnused
Expand All @@ -98,20 +98,20 @@
// probably be a "map[string]interface{}" or "map[interface{}]interface{}".
// See example below:
//
// type Friend struct {
// Name string
// Other map[string]interface{} `mapstructure:",remain"`
// }
// type Friend struct {
// Name string
// Other map[string]interface{} `mapstructure:",remain"`
// }
//
// Given the input below, Other would be populated with the other
// values that weren't used (everything but "name"):
//
// map[string]interface{}{
// "name": "bob",
// "address": "123 Maple St.",
// }
// map[string]interface{}{
// "name": "bob",
// "address": "123 Maple St.",
// }
//
// Omit Empty Values
// # Omit Empty Values
//
// When decoding from a struct to any other value, you may use the
// ",omitempty" suffix on your tag to omit that value if it equates to
Expand All @@ -122,37 +122,37 @@
// field value is zero and a numeric type, the field is empty, and it won't
// be encoded into the destination type.
//
// type Source struct {
// Age int `mapstructure:",omitempty"`
// }
// type Source struct {
// Age int `mapstructure:",omitempty"`
// }
//
// Unexported fields
// # Unexported fields
//
// Since unexported (private) struct fields cannot be set outside the package
// where they are defined, the decoder will simply skip them.
//
// For this output type definition:
//
// type Exported struct {
// private string // this unexported field will be skipped
// Public string
// }
// type Exported struct {
// private string // this unexported field will be skipped
// Public string
// }
//
// Using this map as input:
//
// map[string]interface{}{
// "private": "I will be ignored",
// "Public": "I made it through!",
// }
// map[string]interface{}{
// "private": "I will be ignored",
// "Public": "I made it through!",
// }
//
// The following struct will be decoded:
//
// type Exported struct {
// private: "" // field is left with an empty string (zero value)
// Public: "I made it through!"
// }
// type Exported struct {
// private: "" // field is left with an empty string (zero value)
// Public: "I made it through!"
// }
//
// Other Configuration
// # Other Configuration
//
// mapstructure is highly configurable. See the DecoderConfig struct
// for other features and options that are supported.
Expand Down Expand Up @@ -811,8 +811,14 @@ func (d *Decoder) decodeMap(name string, data interface{}, val reflect.Value) er
valMap = reflect.MakeMap(mapType)
}

dataVal := reflect.ValueOf(data)

// Resolve any levels of indirection
for dataVal.Kind() == reflect.Pointer {
dataVal = reflect.Indirect(dataVal)
}

// Check input type and based on the input type jump to the proper func
dataVal := reflect.Indirect(reflect.ValueOf(data))
switch dataVal.Kind() {
case reflect.Map:
return d.decodeMapFromMap(name, dataVal, val, valMap)
Expand Down Expand Up @@ -1190,7 +1196,6 @@ func (d *Decoder) decodeArray(name string, data interface{}, val reflect.Value)
if dataVal.Len() > arrayType.Len() {
return fmt.Errorf(
"'%s': expected source data to have length less or equal to %d, got %d", name, arrayType.Len(), dataVal.Len())

}

// Make a new array to hold our result, same size as the original data.
Expand Down
110 changes: 107 additions & 3 deletions mapstructure_bugs_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -188,7 +188,6 @@ func TestNestedTypePointerWithDefaults(t *testing.T) {
if result.Vbar.Vuint != 42 {
t.Errorf("vuint value should be 42: %#v", result.Vbar.Vuint)
}

}

type NestedSlice struct {
Expand Down Expand Up @@ -284,7 +283,6 @@ func TestNestedTypeWithDefaults(t *testing.T) {
if result.Vbar.Vuint != 42 {
t.Errorf("vuint value should be 42: %#v", result.Vbar.Vuint)
}

}

// #67 panic() on extending slices (decodeSlice with disabled ZeroValues)
Expand Down Expand Up @@ -526,7 +524,6 @@ func TestDecodeIntermediateMapsSettable(t *testing.T) {
return data, nil
},
})

if err != nil {
t.Fatalf("failed to create decoder: %v", err)
}
Expand Down Expand Up @@ -625,3 +622,110 @@ func TestMapOmitEmptyWithEmptyFieldnameInTag(t *testing.T) {
t.Fatalf("fail: %#v", m)
}
}

// GH-347: Decoding maps with multiple indirection results in an error
func TestDecodeToMapWithMultipleIndirection(t *testing.T) {
t.Run("Struct", func(t *testing.T) {
type Struct struct {
Foo string `mapstructure:"foo"`
}

v := Struct{
Foo: "bar",
}

i := &v
ii := &i
iii := &ii

var actual map[string]interface{}

if err := Decode(iii, &actual); err != nil {
t.Fatal(err)
}

expected := map[string]interface{}{
"foo": "bar",
}

if !reflect.DeepEqual(actual, expected) {
t.Fatalf("expected: %#v, got: %#v", expected, actual)
}
})

t.Run("Map", func(t *testing.T) {
v := map[string]interface{}{
"foo": "bar",
}

i := &v
ii := &i
iii := &ii

var actual map[string]interface{}

if err := Decode(iii, &actual); err != nil {
t.Fatal(err)
}

expected := map[string]interface{}{
"foo": "bar",
}

if !reflect.DeepEqual(actual, expected) {
t.Fatalf("expected: %#v, got: %#v", expected, actual)
}
})

t.Run("Array", func(t *testing.T) {
v := [1]map[string]interface{}{
{
"foo": "bar",
},
}

i := &v
ii := &i
iii := &ii

var actual map[string]interface{}

if err := WeakDecode(iii, &actual); err != nil {
t.Fatal(err)
}

expected := map[string]interface{}{
"foo": "bar",
}

if !reflect.DeepEqual(actual, expected) {
t.Fatalf("expected: %#v, got: %#v", expected, actual)
}
})

t.Run("Slice", func(t *testing.T) {
v := []map[string]interface{}{
{
"foo": "bar",
},
}

i := &v
ii := &i
iii := &ii

var actual map[string]interface{}

if err := WeakDecode(iii, &actual); err != nil {
t.Fatal(err)
}

expected := map[string]interface{}{
"foo": "bar",
}

if !reflect.DeepEqual(actual, expected) {
t.Fatalf("expected: %#v, got: %#v", expected, actual)
}
})
}