decode: Only recursively unslice when the target is an interface{}

This commit is contained in:
Daniel Nephin 2020-06-15 12:22:54 -04:00
parent f613c919d2
commit dad8f29d4e
2 changed files with 82 additions and 12 deletions

View File

@ -94,11 +94,13 @@ func canonicalFieldKey(field reflect.StructField) string {
return parts[0] return parts[0]
} }
// HookWeakDecodeFromSlice looks for []map[string]interface{} in the source // HookWeakDecodeFromSlice looks for []map[string]interface{} and []interface{}
// data. If the target is not a slice or array it attempts to unpack 1 item // in the source data. If the target is not a slice or array it attempts to unpack
// out of the slice. If there are more items the source data is left unmodified, // 1 item out of the slice. If there are more items the source data is left
// allowing mapstructure to handle and report the decode error caused by // unmodified, allowing mapstructure to handle and report the decode error caused by
// mismatched types. // mismatched types. The []interface{} is handled so that all slice types are
// behave the same way, and for the rare case when a raw structure is re-encoded
// to JSON, which will produce the []interface{}.
// //
// If this hook is being used on a "second pass" decode to decode an opaque // If this hook is being used on a "second pass" decode to decode an opaque
// configuration into a type, the DecodeConfig should set WeaklyTypedInput=true, // configuration into a type, the DecodeConfig should set WeaklyTypedInput=true,
@ -122,18 +124,31 @@ func HookWeakDecodeFromSlice(from, to reflect.Type, data interface{}) (interface
switch d := data.(type) { switch d := data.(type) {
case []map[string]interface{}: case []map[string]interface{}:
if len(d) == 1 { switch {
case len(d) != 1:
return data, nil
case to == typeOfEmptyInterface:
return unSlice(d[0]) return unSlice(d[0])
default:
return d[0], nil
} }
// the JSON decoder can apparently decode slices as []interface{}
// a slice map be encoded as []interface{} in some cases
case []interface{}: case []interface{}:
if len(d) == 1 { switch {
case len(d) != 1:
return data, nil
case to == typeOfEmptyInterface:
return unSlice(d[0]) return unSlice(d[0])
default:
return d[0], nil
} }
} }
return data, nil return data, nil
} }
var typeOfEmptyInterface = reflect.TypeOf((*interface{})(nil)).Elem()
func unSlice(data interface{}) (interface{}, error) { func unSlice(data interface{}) (interface{}, error) {
err := reflectwalk.Walk(data, &unSliceWalker{}) err := reflectwalk.Walk(data, &unSliceWalker{})
return data, err return data, err
@ -155,6 +170,11 @@ func (u *unSliceWalker) MapElem(m, k, v reflect.Value) error {
return nil return nil
} }
m.SetMapIndex(k, v.Index(0)) first := v.Index(0)
// The value should always be assignable, but double check to avoid a panic.
if !first.Type().AssignableTo(m.Type().Elem()) {
return nil
}
m.SetMapIndex(k, first)
return nil return nil
} }

View File

@ -198,9 +198,11 @@ func TestTranslationsForType(t *testing.T) {
} }
type nested struct { type nested struct {
O map[string]interface{} O map[string]interface{}
Slice []Item Slice []Item
Item Item Item Item
OSlice []map[string]interface{}
Sub *nested
} }
type Item struct { type Item struct {
@ -215,6 +217,14 @@ slice {
slice { slice {
name = "second" name = "second"
} }
item {
name = "solo"
}
sub {
oslice {
something = "v1"
}
}
` `
target := &nested{} target := &nested{}
err := decodeHCLToMapStructure(source, target) err := decodeHCLToMapStructure(source, target)
@ -222,6 +232,12 @@ slice {
expected := &nested{ expected := &nested{
Slice: []Item{{Name: "first"}, {Name: "second"}}, Slice: []Item{{Name: "first"}, {Name: "second"}},
Item: Item{Name: "solo"},
Sub: &nested{
OSlice: []map[string]interface{}{
{"something": "v1"},
},
},
} }
require.Equal(t, target, expected) require.Equal(t, target, expected)
} }
@ -242,6 +258,40 @@ func decodeHCLToMapStructure(source string, target interface{}) error {
return decoder.Decode(&raw) return decoder.Decode(&raw)
} }
func TestHookWeakDecodeFromSlice_DoesNotModifySliceTargetsFromSliceInterface(t *testing.T) {
raw := map[string]interface{}{
"slice": []interface{}{map[string]interface{}{"name": "first"}},
"item": []interface{}{map[string]interface{}{"name": "solo"}},
"sub": []interface{}{
map[string]interface{}{
"OSlice": []interface{}{
map[string]interface{}{"something": "v1"},
},
"item": []interface{}{map[string]interface{}{"name": "subitem"}},
},
},
}
target := &nested{}
decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
DecodeHook: HookWeakDecodeFromSlice,
Result: target,
})
require.NoError(t, err)
err = decoder.Decode(&raw)
expected := &nested{
Slice: []Item{{Name: "first"}},
Item: Item{Name: "solo"},
Sub: &nested{
OSlice: []map[string]interface{}{
{"something": "v1"},
},
Item: Item{Name: "subitem"},
},
}
require.Equal(t, target, expected)
}
func TestHookWeakDecodeFromSlice_ErrorsWithMultipleNestedBlocks(t *testing.T) { func TestHookWeakDecodeFromSlice_ErrorsWithMultipleNestedBlocks(t *testing.T) {
source := ` source := `
item { item {