74 lines
1.9 KiB
Go
74 lines
1.9 KiB
Go
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package request
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import (
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"net/http"
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"strings"
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)
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func DecodeJSON(w http.ResponseWriter, r *http.Request, dst interface{}) error {
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return decodeJSON(w, r, dst, false)
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}
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func DecodeJSONStrict(w http.ResponseWriter, r *http.Request, dst interface{}) error {
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return decodeJSON(w, r, dst, true)
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}
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func decodeJSON(w http.ResponseWriter, r *http.Request, dst interface{}, disallowUnknownFields bool) error {
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maxBytes := 1_048_576
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r.Body = http.MaxBytesReader(w, r.Body, int64(maxBytes))
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dec := json.NewDecoder(r.Body)
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if disallowUnknownFields {
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dec.DisallowUnknownFields()
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}
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err := dec.Decode(dst)
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if err != nil {
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var syntaxError *json.SyntaxError
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var unmarshalTypeError *json.UnmarshalTypeError
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var invalidUnmarshalError *json.InvalidUnmarshalError
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switch {
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case errors.As(err, &syntaxError):
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return fmt.Errorf("body contains badly-formed JSON (at character %d)", syntaxError.Offset)
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case errors.Is(err, io.ErrUnexpectedEOF):
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return errors.New("body contains badly-formed JSON")
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case errors.As(err, &unmarshalTypeError):
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if unmarshalTypeError.Field != "" {
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return fmt.Errorf("body contains incorrect JSON type for field %q", unmarshalTypeError.Field)
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}
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return fmt.Errorf("body contains incorrect JSON type (at character %d)", unmarshalTypeError.Offset)
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case errors.Is(err, io.EOF):
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return errors.New("body must not be empty")
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case strings.HasPrefix(err.Error(), "json: unknown field "):
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fieldName := strings.TrimPrefix(err.Error(), "json: unknown field ")
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return fmt.Errorf("body contains unknown key %s", fieldName)
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case err.Error() == "http: request body too large":
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return fmt.Errorf("body must not be larger than %d bytes", maxBytes)
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case errors.As(err, &invalidUnmarshalError):
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panic(err)
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default:
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return err
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}
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}
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err = dec.Decode(&struct{}{})
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if !errors.Is(err, io.EOF) {
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return errors.New("body must only contain a single JSON value")
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}
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return nil
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}
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