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

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,
)
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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)
  }
}
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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)
}
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Bring Go lang native middleware into aah

aah expands the possibilities via reuse/existing middlewares.

// 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,
)
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