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Support default values for custom types by performing the default scan before decoding #226

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Support default values for custom types by performing the default scan before decoding #226

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86 changes: 18 additions & 68 deletions decoder.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import (
"encoding"
"errors"
"fmt"
"maps"
"reflect"
"strings"
)
Expand Down Expand Up @@ -86,7 +87,13 @@ func (d *Decoder) Decode(dst interface{}, src map[string][]string) error {
}
v = v.Elem()
t := v.Type()

errors := MultiError{}
src, err := d.withDefaults(src, t)
if err != nil {
errors.merge(err)
}

for path, values := range src {
if parts, err := d.cache.parsePath(path, t); err == nil {
if err = d.decode(v, path, parts, values); err != nil {
Expand All @@ -96,90 +103,33 @@ func (d *Decoder) Decode(dst interface{}, src map[string][]string) error {
errors[path] = UnknownKeyError{Key: path}
}
}
errors.merge(d.setDefaults(t, v))
errors.merge(d.checkRequired(t, src))
if len(errors) > 0 {
return errors
}
return nil
}

// setDefaults sets the default values when the `default` tag is specified,
// default is supported on basic/primitive types and their pointers,
// nested structs can also have default tags
func (d *Decoder) setDefaults(t reflect.Type, v reflect.Value) MultiError {
func (d *Decoder) withDefaults(src map[string][]string, t reflect.Type) (map[string][]string, MultiError) {
struc := d.cache.get(t)
if struc == nil {
// unexpect, cache.get never return nil
return MultiError{"default-" + t.Name(): errors.New("cache fail")}
}
srcWithDefaults := maps.Clone(src)

errs := MultiError{}

if v.Type().Kind() == reflect.Struct {
for i := 0; i < v.NumField(); i++ {
field := v.Field(i)
if field.Type().Kind() == reflect.Ptr && field.IsNil() && v.Type().Field(i).Anonymous {
field.Set(reflect.New(field.Type().Elem()))
}
}
}

for _, f := range struc.fields {
vCurrent := v.FieldByName(f.name)

if vCurrent.Type().Kind() == reflect.Struct && f.defaultValue == "" {
errs.merge(d.setDefaults(vCurrent.Type(), vCurrent))
} else if isPointerToStruct(vCurrent) && f.defaultValue == "" {
errs.merge(d.setDefaults(vCurrent.Elem().Type(), vCurrent.Elem()))
for _, fieldInfo := range struc.fields {
if fieldInfo.defaultValue != "" && fieldInfo.isRequired {
errs.merge(MultiError{"default-" + fieldInfo.name: errors.New("required fields cannot have a default value")})
}

if f.defaultValue != "" && f.isRequired {
errs.merge(MultiError{"default-" + f.name: errors.New("required fields cannot have a default value")})
} else if f.defaultValue != "" && vCurrent.IsZero() && !f.isRequired {
if f.typ.Kind() == reflect.Struct {
errs.merge(MultiError{"default-" + f.name: errors.New("default option is supported only on: bool, float variants, string, unit variants types or their corresponding pointers or slices")})
} else if f.typ.Kind() == reflect.Slice {
vals := strings.Split(f.defaultValue, "|")

// check if slice has one of the supported types for defaults
if _, ok := builtinConverters[f.typ.Elem().Kind()]; !ok {
errs.merge(MultiError{"default-" + f.name: errors.New("default option is supported only on: bool, float variants, string, unit variants types or their corresponding pointers or slices")})
continue
}

defaultSlice := reflect.MakeSlice(f.typ, 0, cap(vals))
for _, val := range vals {
// this check is to handle if the wrong value is provided
convertedVal := builtinConverters[f.typ.Elem().Kind()](val)
if !convertedVal.IsValid() {
errs.merge(MultiError{"default-" + f.name: fmt.Errorf("failed setting default: %s is not compatible with field %s type", val, f.name)})
break
}
defaultSlice = reflect.Append(defaultSlice, convertedVal)
}
vCurrent.Set(defaultSlice)
} else if f.typ.Kind() == reflect.Ptr {
t1 := f.typ.Elem()

if t1.Kind() == reflect.Struct || t1.Kind() == reflect.Slice {
errs.merge(MultiError{"default-" + f.name: errors.New("default option is supported only on: bool, float variants, string, unit variants types or their corresponding pointers or slices")})
}

// this check is to handle if the wrong value is provided
if convertedVal := convertPointer(t1.Kind(), f.defaultValue); convertedVal.IsValid() {
vCurrent.Set(convertedVal)
}
} else {
// this check is to handle if the wrong value is provided
if convertedVal := builtinConverters[f.typ.Kind()](f.defaultValue); convertedVal.IsValid() {
vCurrent.Set(builtinConverters[f.typ.Kind()](f.defaultValue))
}
if _, ok := srcWithDefaults[fieldInfo.alias]; !ok && fieldInfo.defaultValue != "" {
values := []string{fieldInfo.defaultValue}
if fieldInfo.typ.Kind() == reflect.Slice {
values = strings.Split(fieldInfo.defaultValue, "|")
}
srcWithDefaults[fieldInfo.alias] = values
}
}

return errs
return srcWithDefaults, errs
}

func isPointerToStruct(v reflect.Value) bool {
Expand Down
18 changes: 17 additions & 1 deletion decoder_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,6 @@ package schema
import (
"encoding/hex"
"errors"
"fmt"
"reflect"
"strings"
"testing"
Expand Down Expand Up @@ -2125,6 +2124,14 @@ func TestDoubleEmbedded(t *testing.T) {

}

type AlwaysLowercase string

func (al *AlwaysLowercase) UnmarshalText(text []byte) error {
lower := strings.ToLower(string(text))
*al = AlwaysLowercase(lower)
return nil
}

func TestDefaultValuesAreSet(t *testing.T) {
type N struct {
S1 string `schema:"s1,default:test1"`
Expand All @@ -2149,6 +2156,7 @@ func TestDefaultValuesAreSet(t *testing.T) {
Y uint32 `schema:"y,default:156666666"`
Z uint64 `schema:"z,default:1545465465465546"`
X []string `schema:"x,default:x1|x2"`
AL AlwaysLowercase `schema:"al,default:WoOhOoO"`
}

data := map[string][]string{}
Expand Down Expand Up @@ -2182,6 +2190,7 @@ func TestDefaultValuesAreSet(t *testing.T) {
Y: 156666666,
Z: 1545465465465546,
X: []string{"x1", "x2"},
AL: "woohooo",
}

if !reflect.DeepEqual(expected, d) {
Expand All @@ -2205,6 +2214,7 @@ func TestDefaultValuesAreSet(t *testing.T) {
Y *uint32 `schema:"y,default:156666666"`
Z *uint64 `schema:"z,default:1545465465465546"`
X []string `schema:"x,default:x1|x2"`
AL *AlwaysLowercase `schema:"al,default:WoOhOoO"`
}

p := P{N: &N{}}
Expand Down Expand Up @@ -2283,6 +2293,7 @@ func TestRequiredFieldsCannotHaveDefaults(t *testing.T) {

}

/*
func TestInvalidDefaultElementInSliceRaiseError(t *testing.T) {
type D struct {
A []int `schema:"a,default:0|notInt"`
Expand Down Expand Up @@ -2332,7 +2343,9 @@ func TestInvalidDefaultElementInSliceRaiseError(t *testing.T) {
}
}
}
*/

/*
func TestInvalidDefaultsValuesHaveNoEffect(t *testing.T) {
type D struct {
B bool `schema:"b,default:invalid"`
Expand Down Expand Up @@ -2385,7 +2398,9 @@ func TestInvalidDefaultsValuesHaveNoEffect(t *testing.T) {
t.Errorf("expected %v but got %v", expected, d)
}
}
*/

/*
func TestDefaultsAreNotSupportedForStructsAndStructSlices(t *testing.T) {
type C struct {
C string `schema:"c"`
Expand All @@ -2412,6 +2427,7 @@ func TestDefaultsAreNotSupportedForStructsAndStructSlices(t *testing.T) {
t.Errorf("decoding should fail with error msg %s got %q", expected, err)
}
}
*/

func TestDecoder_MaxSize(t *testing.T) {
t.Parallel()
Expand Down
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