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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2017 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package jsonutil
import (
"encoding/json"
"fmt"
"io"
"reflect"
"strings"
"github.com/snapcore/snapd/strutil"
)
// DecodeWithNumber decodes input data using json.Decoder, ensuring numbers are preserved
// via json.Number data type. It errors out on invalid json or any excess input.
func DecodeWithNumber(r io.Reader, value any) error {
dec := json.NewDecoder(r)
dec.UseNumber()
if err := dec.Decode(&value); err != nil {
return err
}
if dec.More() {
return fmt.Errorf("cannot parse json value")
}
return nil
}
// StructFields takes a pointer to a struct and a list of exceptions,
// and returns a list of the fields in the struct that are JSON-tagged
// and whose tag is not in the list of exceptions.
// The struct can be nil.
func StructFields(s any, exceptions ...string) []string {
st := reflect.TypeOf(s).Elem()
num := st.NumField()
fields := make([]string, 0, num)
for i := 0; i < num; i++ {
tag := st.Field(i).Tag.Get("json")
idx := strings.IndexByte(tag, ',')
if idx > -1 {
tag = tag[:idx]
}
if tag != "" && !strutil.ListContains(exceptions, tag) {
fields = append(fields, tag)
}
}
return fields
}
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