initial public commit

tools/rest/multi_binder.go

@@ -0,0 +1,59 @@
+package rest
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/labstack/echo/v5"
+)
+
+// BindBody binds request body content to i.
+//
+// This is similar to `echo.BindBody()`, but for JSON requests uses
+// custom json reader that **copies** the request body, allowing multiple reads.
+func BindBody(c echo.Context, i interface{}) error {
+	req := c.Request()
+	if req.ContentLength == 0 {
+		return nil
+	}
+
+	ctype := req.Header.Get(echo.HeaderContentType)
+	switch {
+	case strings.HasPrefix(ctype, echo.MIMEApplicationJSON):
+		err := ReadJsonBodyCopy(c.Request(), i)
+		if err != nil {
+			return echo.NewHTTPErrorWithInternal(http.StatusBadRequest, err, err.Error())
+		}
+		return nil
+	default:
+		// fallback to the default binder
+		return echo.BindBody(c, i)
+	}
+}
+
+// ReadJsonBodyCopy reads the request body into i by
+// creating a copy of `r.Body` to allow multiple reads.
+func ReadJsonBodyCopy(r *http.Request, i interface{}) error {
+	body := r.Body
+
+	// this usually shouldn't be needed because the Server calls close for us
+	// but we are changing the request body with a new reader
+	defer body.Close()
+
+	limitReader := io.LimitReader(body, DefaultMaxMemory)
+
+	bodyBytes, readErr := io.ReadAll(limitReader)
+	if readErr != nil {
+		return readErr
+	}
+
+	err := json.NewDecoder(bytes.NewReader(bodyBytes)).Decode(i)
+
+	// set new body reader
+	r.Body = io.NopCloser(bytes.NewReader(bodyBytes))
+
+	return err
+}