middleware.md

Title: Middlewares Desc: aah framework provides a way to create user-defined Middleware for application very similar to Go lang standard middleware. Bring Go lang native middleware into aah. Keywords: middleware, writing middleware, abort middleware, native middleware into aah

Middlewares

aah provides a way to create user-defined Middleware for your application very similar to Go lang standard middleware.

Table of Contents

• Writing Middleware
• Abort the Middleware Flow
• Bring Go lang native middleware into aah

Writing Middleware

To create custom middleware, just comply to aah.MiddlewareFunc. Once you created the middleware function.

Steps to add user-defined middleware(s) into aah

• Create a middleware in appropriate package
• Go to file <app-base-dir>/app/init.go
• Look for HTTPEngine().Middlewares(
• Add your middleware into the chain

func MyCustomMiddleware1(ctx *Context, m *Middleware) {
  // do your logic before calling next middleware

  // continue the chain
  m.Next(ctx)

  // do your logic after the continues of middleware chain
}

func MyCustomMiddleware2(ctx *Context, m *Middleware) {
  // do your logic before calling next middleware

  // continue the chain
  m.Next(ctx)

  // do your logic after the continues of middleware chain
}

// Add it on file `<app-base-dir>/app/init.go`
app.HTTPEngine().Middlewares(
  aah.RouteMiddleware,
  aah.CORSMiddleware,
  aah.BindMiddleware,
  aah.AntiCSRFMiddleware,
  aah.AuthcAuthzMiddleware,
  MyCustomMiddleware1,
  MyCustomMiddleware2,
  aah.ActionMiddleware,
)

Abort the Middleware Flow

You can abort the middleware flow in two ways.

Way One

func customMiddleware(ctx *Context, m *Middleware) {
  // do your logic before and have control flag to
  // whether to call next middleware or not
  goodToProceed := false

  // continue the chain
  if goodToProceed {
    m.Next(ctx)
  }
}

Way Two

func customMiddleware(ctx *Context, m *Middleware) {
  // do your complex application logic and conditions
  // ...
  ctx.Abort()
  // ...


  // Even though `Next(..)` method is called, framework won't proceed further
  // because `Abort()` have been called before
  m.Next(ctx)
}

Bring Go lang native middleware into aah

aah expands the possibilities via reuse/existing middlewares.

• http.Handler
• http.HandlerFunc
• func(http.ResponseWriter, *http.Request)

// PrintRequestURL middleware
func PrintRequestURL(w http.ResponseWriter, r *http.Request) {
  fmt.Println("URL:", r.URL.Path)
}

// Add it on file `<app-base-dir>/app/init.go`
app.HTTPEngine().Middlewares(
  aah.RouteMiddleware,
  aah.CORSMiddleware,
  aah.BindMiddleware,
  aah.AntiCSRFMiddleware,
  aah.AuthcAuthzMiddleware,
  aah.ToMiddleware(PrintRequestURL),
  aah.ActionMiddleware,
)