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vweb: middleware implementation (#17730)
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‎examples/vweb/middleware/templates/base.html

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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="UTF-8">
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<meta http-equiv="X-UA-Compatible" content="IE=edge">
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<title>@title</title>
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</head>
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<body>
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<nav>
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<a href="/">Home</a>
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<a href="/admin/secrets">"/admin/secrets"</a>
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<a href="/admin/dynamic">"/admin/dynamic"</a>
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<a href="/early">Early exit</a>
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</nav>
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<main>
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@content
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</main>
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<footer></footer>
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</body>
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</html>

‎examples/vweb/middleware/templates/early.html

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<p>Early exit</p>

‎examples/vweb/middleware/templates/index.html

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<h1>Hello </h1>

‎examples/vweb/middleware/templates/secret.html

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<p>Super secret stuff</p>

‎examples/vweb/middleware/vweb_example.v

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module main
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import vweb
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// for another example see vlib/vweb/tests/middleware_test_server.v
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const (
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http_port = 8080
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)
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struct App {
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vweb.Context
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middlewares map[string][]vweb.Middleware
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mut:
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is_authenticated bool
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}
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fn main() {
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mut app := new_app()
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vweb.run(app, http_port)
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}
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fn new_app() &App {
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mut app := &App{
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middlewares: {
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// chaining is allowed, middleware will be evaluated in order
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'/admin/': [other_func1, other_func2]
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'/early': [middleware_early]
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}
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}
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// do stuff with app
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// ...
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return app
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}
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['/']
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pub fn (mut app App) index() vweb.Result {
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println('Index page')
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title := 'Home Page'
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content := $tmpl('templates/index.html')
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base := $tmpl('templates/base.html')
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return app.html(base)
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}
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[middleware: check_auth]
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['/admin/secrets']
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pub fn (mut app App) secrets() vweb.Result {
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println('Secrets page')
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title := 'Secret Admin Page'
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content := $tmpl('templates/secret.html')
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base := $tmpl('templates/base.html')
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return app.html(base)
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}
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['/admin/:sub']
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pub fn (mut app App) dynamic(sub string) vweb.Result {
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println('Dynamic page')
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title := 'Secret dynamic'
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content := sub
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base := $tmpl('templates/base.html')
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return app.html(base)
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}
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['/early']
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pub fn (mut app App) early() vweb.Result {
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println('Early page')
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title := 'Early Exit'
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content := $tmpl('templates/early.html')
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base := $tmpl('templates/base.html')
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return app.html(base)
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}
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// is always executed first!
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pub fn (mut app App) before_request() {
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app.is_authenticated = false
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println('0')
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}
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pub fn (mut app App) check_auth() bool {
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println('3')
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if app.is_authenticated == false {
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app.redirect('/')
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}
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return app.is_authenticated
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}
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fn other_func1(mut ctx vweb.Context) bool {
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println('1')
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return true
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}
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fn other_func2(mut ctx vweb.Context) bool {
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println('2')
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// ...
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return true
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}
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fn middleware_early(mut ctx vweb.Context) bool {
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println('4')
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ctx.text(':(')
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// returns false, so the middleware propogation is stopped and the user will see the text ":("
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return false
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}

‎vlib/vweb/README.md

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@@ -252,9 +252,10 @@ pub fn (mut app App) controller_get_user_by_id() vweb.Result {
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```
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### Middleware
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V haven't a well defined middleware.
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For now, you can use `before_request()`. This method called before every request.
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Probably you can use it for check user session cookie or add header
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Vweb has different kinds of middleware.
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The `before_request()` method is always called before every request before any
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other middleware is processed. You could use it to check user session cookies or to add a header.
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**Example:**
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```v ignore
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}
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```
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Middleware functions can be passed directly when creating an App instance and is
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executed when the url starts with the defined key.
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In the following example, if a user navigates to `/path/to/test` the middleware
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is executed in the following order: `middleware_func`, `other_func`, `global_middleware`.
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The middleware is executed in the same order as they are defined and if any function in
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the chain returns `false` the propogation is stopped.
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**Example:**
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```v
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module main
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import vweb
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struct App {
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vweb.Context
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middlewares map[string][]vweb.Middleware
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}
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fn new_app() &App {
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mut app := &App{
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middlewares: {
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// chaining is allowed, middleware will be evaluated in order
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'/path/to/': [middleware_func, other_func]
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'/': [global_middleware]
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}
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}
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// do stuff with app
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// ...
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return app
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}
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fn middleware_func(mut ctx vweb.Context) bool {
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// ...
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return true
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}
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fn other_func(mut ctx vweb.Context) bool {
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// ...
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return true
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}
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fn global_middleware(mut ctx vweb.Context) bool {
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// ...
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return true
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}
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```
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Middleware functions will be of type `vweb.Middleware` and are not methods of App,
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so they could also be imported from other modules.
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```v ignore
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pub type Middleware = fn (mut Context) bool
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```
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Middleware can also be added to route specific functions via attributes.
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**Example:**
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```v ignore
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[middleware: check_auth]
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['/admin/data']
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pub fn (mut app App) admin() vweb.Result {
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// ...
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}
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// check_auth is a method of App, so we don't need to pass the context as parameter.
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pub fn (mut app App) check_auth () bool {
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// ...
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return true
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}
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```
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For now you can only add 1 middleware to a route specific function via attributes.
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### Redirect
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Used when you want be redirected to an url
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**Examples:**
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```v ignore
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pub fn (mut app App) before_request() {
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app.user_id = app.get_cookie('id') or { app.redirect('/') }
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app.user_id = app.get_cookie('id') or { app.redirect('/') }
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}
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```
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```v ignore
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['/articles'; get]
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pub fn (mut app App) articles() vweb.Result {
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if !app.token {
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app.redirect('/login')
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}
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return app.text("patatoes")
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if !app.token {
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app.redirect('/login')
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}
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return app.text('patatoes')
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}
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```
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You can also combine middleware and redirect.
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**Example:**
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```v ignore
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[middleware: with_auth]
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['/admin/secret']
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pub fn (mut app App) admin_secret() vweb.Result {
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// this code should never be reached
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return app.text('secret')
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}
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['/redirect']
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pub fn (mut app App) with_auth() bool {
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app.redirect('/auth/login')
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return false
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}
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```
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‎vlib/vweb/parse.v

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import net.http
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// Parsing function attributes for methods and path.
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fn parse_attrs(name string, attrs []string) !([]http.Method, string) {
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fn parse_attrs(name string, attrs []string) !([]http.Method, string, string) {
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if attrs.len == 0 {
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return [http.Method.get], '/${name}'
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return [http.Method.get], '/${name}', ''
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}
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mut x := attrs.clone()
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mut methods := []http.Method{}
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mut middleware := ''
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mut path := ''
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for i := 0; i < x.len; {
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x.delete(i)
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continue
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}
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if attr.starts_with('middleware:') {
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middleware = attr.all_after('middleware:').trim_space()
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x.delete(i)
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continue
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}
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i++
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}
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if x.len > 0 {
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path = '/${name}'
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}
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// Make path lowercase for case-insensitive comparisons
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return methods, path.to_lower()
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return methods, path.to_lower(), middleware
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}
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fn parse_query_from_url(url urllib.URL) map[string]string {

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