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webmiddleware.go
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/
webmiddleware.go
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// Copyright © 2020 The Things Network Foundation, The Things Industries B.V.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package webmiddleware provides middleware for http Handlers.
package webmiddleware
import "net/http"
// MiddlewareFunc is a function that acts as middleware for http Handlers.
type MiddlewareFunc func(next http.Handler) http.Handler
// Chain returns a http.Handler that chains the middleware onion-style around the handler.
func Chain(middlewares []MiddlewareFunc, handler http.Handler) http.Handler {
for i := len(middlewares) - 1; i >= 0; i-- {
handler = middlewares[i](handler)
}
return handler
}
// Conditional is a middleware that only executes middleware if the condition
// returns true for the request. If the condition returns false, the middleware
// is skipped, and request handling moves on to the next handler in the chain.
func Conditional(middleware MiddlewareFunc, condition func(r *http.Request) bool) MiddlewareFunc {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
handler := next
if condition(r) {
handler = middleware(next)
}
handler.ServeHTTP(w, r)
})
}
}