116 lines
2.9 KiB
Go
116 lines
2.9 KiB
Go
package utils
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import (
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"encoding/json"
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"fmt"
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"io"
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"mime/multipart"
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"reflect"
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"slices"
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"strconv"
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"strings"
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)
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// Encode writes struct fields into multipart form-data using json tags as field names.
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func Encode[T any](w *multipart.Writer, req T) error {
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v := unwrapMultipartValue(reflect.ValueOf(req))
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if !v.IsValid() || v.Kind() != reflect.Struct {
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return fmt.Errorf("req must be a struct")
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}
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t := v.Type()
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for i := 0; i < v.NumField(); i++ {
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field := v.Field(i)
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fieldType := t.Field(i)
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jsonTag := fieldType.Tag.Get("json")
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if jsonTag == "" {
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jsonTag = fieldType.Name
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}
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parts := strings.Split(jsonTag, ",")
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fieldName := parts[0]
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if fieldName == "" {
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fieldName = fieldType.Name
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}
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if fieldName == "-" {
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continue
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}
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// Handle omitempty
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isEmpty := field.IsZero()
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if slices.Contains(parts, "omitempty") && isEmpty {
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continue
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}
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if err := writeMultipartField(w, fieldName, fieldType.Tag.Get("filename"), field); err != nil {
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return err
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}
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}
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return nil
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}
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func unwrapMultipartValue(v reflect.Value) reflect.Value {
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for v.IsValid() && (v.Kind() == reflect.Pointer || v.Kind() == reflect.Interface) {
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if v.IsNil() {
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return reflect.Value{}
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}
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v = v.Elem()
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}
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return v
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}
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func writeMultipartField(w *multipart.Writer, fieldName, filename string, field reflect.Value) error {
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value := unwrapMultipartValue(field)
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if !value.IsValid() {
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return nil
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}
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switch value.Kind() {
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case reflect.String:
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return writeMultipartValue(w, fieldName, []byte(value.String()))
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return writeMultipartValue(w, fieldName, []byte(strconv.FormatInt(value.Int(), 10)))
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
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return writeMultipartValue(w, fieldName, []byte(strconv.FormatUint(value.Uint(), 10)))
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case reflect.Float32:
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return writeMultipartValue(w, fieldName, []byte(strconv.FormatFloat(value.Float(), 'f', -1, 32)))
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case reflect.Float64:
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return writeMultipartValue(w, fieldName, []byte(strconv.FormatFloat(value.Float(), 'f', -1, 64)))
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case reflect.Bool:
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return writeMultipartValue(w, fieldName, []byte(strconv.FormatBool(value.Bool())))
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case reflect.Slice:
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if value.Type().Elem().Kind() == reflect.Uint8 {
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if filename == "" {
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filename = fieldName
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}
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fw, err := w.CreateFormFile(fieldName, filename)
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if err != nil {
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return err
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}
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_, err = fw.Write(value.Bytes())
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return err
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}
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}
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// Telegram expects nested objects and arrays in multipart requests as JSON strings.
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data, err := json.Marshal(value.Interface())
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if err != nil {
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return err
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}
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if string(data) == "null" {
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return nil
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}
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return writeMultipartValue(w, fieldName, data)
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}
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func writeMultipartValue(w *multipart.Writer, fieldName string, value []byte) error {
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fw, err := w.CreateFormField(fieldName)
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if err != nil {
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return err
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}
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_, err = io.Copy(fw, strings.NewReader(string(value)))
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return err
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}
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