middleware.md

Middleware

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Table of Contents

• Middleware
  • API
  • Sample

API

proc middleware*(
  self:var Routes,
  path:Regex,
  action:proc(r:Request, p:Params):Future[Response]
) =

proc middleware*(
  self:var Routes,
  httpMethods:seq[HttpMethod],
  path:Regex,
  action:proc(r:Request, p:Params):Future[Response]
) =

proc next*(status:HttpCode=HttpCode(200), body="", headers:Headers=newHeaders()):Response =

Sample

You can run middleware methods before calling controller.
In following example, checkCsrfTokenMiddleware() and checkSessionIdMiddleware() definded in app/middleware/auth_middlware.nim are called

main.nim

import basolato
import app/middlewares/auth_middleware


let ROUTES = @[
  Route.get("/", welcome_rontroller.index)
    .middleware(auth_middleware.checkLoginIdMiddleware)
]

serve(routes)

app/middleware/auth_middlware.nim

import asyncdispatch
import basolato/middleware


proc checkLoginId*(c:Context, p:Params):Future[Response] {.async.} =
  if not c.request.headers.hasKey("X-login-id"):
    return render(Http403, "X-login-id is missing in request header")

  if not c.request.headers.hasKey("X-login-token"):
    return render(Http403, "X-login-token is missing in request header")

  return next()

If X-login-id or X-login-token are missing in request header, return 403 otherwise 200.

---

If you want to redirect the user to the login page when the login check fails, use errorRedirect. This will call HTTP 303.

app/middleware/auth_middlware.nim

import basolato/middleware

proc checkLoginId*(c:Context, p:Params):Future[Response] {.async.} =
  if not c.request.headers.hasKey("X-login-id"):
    return errorRedirect("/login")

  if not c.request.headers.hasKey("X-login-token"):
    return errorRedirect("/login")

  return next()

---

As in CORS, if you want to return a response made by the middleware to the client instead of the controller, you can set an argument to the next proc.
In following example, setCorsMiddleware run only in OPTIONS requests.

main.nim

let ROUTES = @[
  Route.put("/api/user/{id:int}", user_controller.update)
    .middleware(cors_middleware.setCorsMiddleware),
]

app/middleware/cors_middlware.nim

proc setCorsMiddleware*(c:Context, p:Params):Future[Response] {.async.} =
  if c.request.httpMethod == HttpOption:
    let headers = corsHeader() & secureHeader()
    return next(status=Http204, headers=headers)