conditional

Conditional Requests Middleware

What it does

Handles If-None-Match, If-Match, If-Modified-Since, and related precondition headers using configured ETag or Last-Modified functions.

How to implement

package main

import (
	"github.com/oarkflow/fh"
	"github.com/oarkflow/fh/mw/conditional"
)

func main() {
	app := fh.New()
	app.Use(conditional.New(conditional.Config{ETag: func(c fh.Ctx) string { return `"v1"` }}))

	app.Get("/", func(c fh.Ctx) error {
		return c.Status(fh.StatusOK).SendString("ok")
	})
}

Impact

Reduces bandwidth and handler work when clients have fresh cached data. It can return 304 or precondition failures.

Ordering guidance

Run before expensive handlers if tags can be computed cheaply. Pair with ETag/static/cache middleware.

Production considerations

Use strong validators for write preconditions. Ensure ETags change whenever the representation changes.