Echo Binder Plugin

Replaces Echo's DefaultBinder so every c.Bind() call on POST/PUT/PATCH runs validator.UnmarshalInto — enforcing required fields, defaults, and all validate constraints automatically. GET/DELETE/HEAD requests fall back to Echo's own DefaultBinder (path + query params only) — pedantigo is never invoked for those methods.

Install

go get github.com/SmrutAI/pedantigo/v2/plugins/web/echo@v2.0.0

Setup

import pedantigoecho "github.com/SmrutAI/pedantigo/v2/plugins/web/echo"

e := echo.New()
e.Binder = pedantigoecho.NewBinder()

How it works

• POST/PUT/PATCH: reads the request body → calls validator.UnmarshalInto(body, target) → enforces required fields, defaults, and constraints. Returns an echo.HTTPError with status 400 on validation failure.
• GET/DELETE/HEAD: falls back to Echo's DefaultBinder (BindPathParams + BindQueryParams). No pedantigo validation runs for these methods.
• Empty POST/PUT/PATCH body: returns nil (no error).

Registration requirement

Every request struct passed to c.Bind() must be registered once, at package init time, with validator.Register(validator.New[T]()):

var _ = validator.Register(validator.New[CreateRequest]())

If a type is never registered, UnmarshalInto panics with a message naming the missing type and this exact fix. If Register is called twice for the same type, it panics too — a type may only be registered once; find the duplicate call and remove it.

Before / after

Before (manual io.ReadAll + Unmarshal):

var createValidator = validator.New[CreateRequest]()

func (h *Handler) Create(c echo.Context) error {
	body, err := io.ReadAll(c.Request().Body)
	if err != nil {
		return echo.NewHTTPError(http.StatusBadRequest, "failed to read body")
	}
	req, err := createValidator.Unmarshal(body)
	if err != nil {
		return echo.NewHTTPError(http.StatusBadRequest, err.Error())
	}
	// use req...
}

After (with the Echo Binder installed):

var _ = validator.Register(validator.New[CreateRequest]())

func (h *Handler) Create(c echo.Context) error {
	var req CreateRequest
	if err := c.Bind(&req); err != nil {
		return err
	}
	// use &req...
}