23 KiB
vweb - the V Web Server
A simple yet powerful web server with built-in routing, parameter handling, templating, and other features. The gitly site is based on vweb.
Some features may not be complete, and have some bugs.
Quick Start
Just run v new <name> web in your terminal
Features
- Very fast performance of C on the web.
- Small binary hello world website is <100 KB.
- Easy to deploy just one binary file that also includes all templates. No need to install any dependencies.
- Templates are precompiled all errors are visible at compilation time, not at runtime.
- Multithreaded by default
Examples
There are some examples that can be explored here.
And others like:
- vweb_orm_jwt (back-end)
- vorum (front-end)
- gitly (full-stack)
Front-end getting start example
src/main.v
module main
import vweb
import os
struct App {
vweb.Context
}
struct Object {
title string
description string
}
fn main() {
vweb.run_at(new_app(), vweb.RunParams{
port: 8081
}) or { panic(err) }
}
fn new_app() &App {
mut app := &App{}
// makes all static files available.
app.mount_static_folder_at(os.resource_abs_path('.'), '/')
return app
}
['/']
pub fn (mut app App) page_home() vweb.Result {
// all this constants can be accessed by src/templates/page/home.html file.
page_title := 'V is the new V'
v_url := 'https://github.com/vlang/v'
list_of_object := [
Object{
title: 'One good title'
description: 'this is the first'
},
Object{
title: 'Other good title'
description: 'more one'
},
]
// $vweb.html() in `<folder>_<name> vweb.Result ()` like this
// render the `<name>.html` in folder `./templates/<folder>`
return $vweb.html()
}
$vweb.html() compiles an HTML template into V during compilation, and embeds the resulting code
into the current action.
That means that the template automatically has access to that action's entire environment.
src/templates/page/home.html
<html>
<header>
<title>${page_title}</title>
@css 'src/templates/page/home.css'
</header>
<body>
<h1 class="title">Hello, Vs.</h1>
@for var in list_of_object
<div>
<a href="${v_url}">${var.title}</a>
<span>${var.description}</span>
</div>
@end
<div>@include 'component.html'</div>
</body>
</html>
src/templates/page/component.html
<div>This is a component</div>
src/templates/page/home.css
h1.title {
font-family: Arial, Helvetica, sans-serif;
color: #3b7bbf;
}
V supports Template directives like
@css, @js for static files in <path>
@if, @for for conditional and loop
and
@include to include html components.
Deploying vweb apps
Everything, including HTML templates, is in one binary file. That's all you need to deploy.
Getting Started
To start with vweb, you have to import the module vweb and define a struct to hold vweb.Context
(and any other variables your program will need).
The web server can be started by calling vweb.run(&App{}, port) or vweb.run(&App{}, RunParams)
Example:
import vweb
struct App {
vweb.Context
}
fn main() {
vweb.run(&App{}, 8080)
// // or
// vweb.run_at(new_app(), vweb.RunParams{
// host: 'localhost'
// port: 8099
// family: .ip
// }) or { panic(err) }
}
Defining endpoints
To add endpoints to your web server, you have to extend the App struct.
For routing you can either use auto-mapping of function names or specify the path as an attribute.
The function expects a response of the type vweb.Result.
Example:
// This endpoint can be accessed via http://localhost:port/hello
fn (mut app App) hello() vweb.Result {
return app.text('Hello')
}
// This endpoint can be accessed via http://localhost:port/foo
["/foo"]
fn (mut app App) world() vweb.Result {
return app.text('World')
}
- HTTP verbs
To use any HTTP verbs (or methods, as they are properly called),
such as [post], [get], [put], [patch] or [delete]
you can simply add the attribute before the function definition.
Example:
[post]
fn (mut app App) world() vweb.Result {
return app.text('World')
}
['/product/create'; post]
fn (mut app App) create_product() vweb.Result {
return app.text('product')
}
- Parameters
Parameters are passed directly in endpoint route using colon sign : and received using the same
name at function
To pass a parameter to an endpoint, you simply define it inside an attribute, e. g.
['/hello/:user].
After it is defined in the attribute, you have to add it as a function parameter.
Example:
vvvv
['/hello/:user'] vvvv
fn (mut app App) hello_user(user string) vweb.Result {
return app.text('Hello $user')
}
You have access to the raw request data such as headers
or the request body by accessing app (which is vweb.Context).
If you want to read the request body, you can do that by calling app.req.data.
To read the request headers, you just call app.req.header and access the
header you want example. app.req.header.get(.content_type). See struct Header
for all available methods (v doc net.http Header).
It has, too, fields for the query, form, files.
- Query
To handle the query context, you just need use the query field
Example:
module main
import vweb
struct App {
vweb.Context
}
fn main() {
vweb.run(&App{}, 8081)
}
['/user'; get]
pub fn (mut app App) controller_get_user_by_id() vweb.Result {
// http://localhost:3000/user?q=vpm&order_by=desc => { 'q': 'vpm', 'order_by': 'desc' }
return app.text(app.query.str())
}
Middleware
Vweb has different kinds of middleware.
The before_request() method is always called before every request before any
other middleware is processed. You could use it to check user session cookies or to add a header.
Example:
pub fn (mut app App) before_request() {
app.user_id = app.get_cookie('id') or { '0' }
}
Middleware functions can be passed directly when creating an App instance and is executed when the url starts with the defined key.
In the following example, if a user navigates to /path/to/test the middleware
is executed in the following order: middleware_func, other_func, global_middleware.
The middleware is executed in the same order as they are defined and if any function in
the chain returns false the propogation is stopped.
Example:
module main
import vweb
struct App {
vweb.Context
middlewares map[string][]vweb.Middleware
}
fn new_app() &App {
mut app := &App{
middlewares: {
// chaining is allowed, middleware will be evaluated in order
'/path/to/': [middleware_func, other_func]
'/': [global_middleware]
}
}
// do stuff with app
// ...
return app
}
fn middleware_func(mut ctx vweb.Context) bool {
// ...
return true
}
fn other_func(mut ctx vweb.Context) bool {
// ...
return true
}
fn global_middleware(mut ctx vweb.Context) bool {
// ...
return true
}
Middleware functions will be of type vweb.Middleware and are not methods of App,
so they could also be imported from other modules.
pub type Middleware = fn (mut Context) bool
Middleware can also be added to route specific functions via attributes.
Example:
[middleware: check_auth]
['/admin/data']
pub fn (mut app App) admin() vweb.Result {
// ...
}
// check_auth is a method of App, so we don't need to pass the context as parameter.
pub fn (mut app App) check_auth () bool {
// ...
return true
}
For now you can only add 1 middleware to a route specific function via attributes.
Redirect
Used when you want be redirected to an url
Examples:
pub fn (mut app App) before_request() {
app.user_id = app.get_cookie('id') or { app.redirect('/') }
}
['/articles'; get]
pub fn (mut app App) articles() vweb.Result {
if !app.token {
app.redirect('/login')
}
return app.text('patatoes')
}
You can also combine middleware and redirect.
Example:
[middleware: with_auth]
['/admin/secret']
pub fn (mut app App) admin_secret() vweb.Result {
// this code should never be reached
return app.text('secret')
}
['/redirect']
pub fn (mut app App) with_auth() bool {
app.redirect('/auth/login')
return false
}
Fallback route
You can implement a fallback not_found route that is called when a request is made and no
matching route is found.
Example:
pub fn (mut app App) not_found() vweb.Result {
app.set_status(404, 'Not Found')
return app.html('<h1>Page not found</h1>')
}
Databases
The db field in a vweb app is reserved for database connections. The connection is
copied to each new request.
Example:
module main
import vweb
import db.sqlite
struct App {
vweb.Context
mut:
db sqlite.DB
}
fn main() {
// create the database connection
mut db := sqlite.connect('db')!
vweb.run(&App{
db: db
}, 8080)
}
Multithreading
By default, a vweb app is multithreaded, that means that multiple requests can
be handled in parallel by using multiple CPU's: a worker pool. You can
change the number of workers (maximum allowed threads) by altering the nr_workers
option. The default behaviour is to use the maximum number of jobs (cores in most cases).
Example:
fn main() {
// assign a maximum of 4 workers
vweb.run_at(&App{}, nr_workers: 4)
}
Database Pool
A single connection database works fine if you run your app with 1 worker, of if you access a file-based database like a sqlite file.
This approach will fail when using a non-file based database connection like a mysql connection to another server somewhere on the internet. Multiple threads would need to access the same connection at the same time.
To resolve this issue, you can use the vweb's built-in database pool. The database pool will keep a number of connections open when the app is started and each worker is assigned its own connection.
Let's look how we can improve our previous example with database pooling and using a postgresql server instead.
Example:
module main
import vweb
import db.pg
struct App {
vweb.Context
db_handle vweb.DatabasePool[pg.DB]
mut:
db pg.DB
}
fn get_database_connection() pg.DB {
// insert your own credentials
return pg.connect(user: 'user', password: 'password', dbname: 'database') or { panic(err) }
}
fn main() {
// create the database pool and pass our `get_database_connection` function as handler
pool := vweb.database_pool(handler: get_database_connection)
// no need to set the `db` field
vweb.run(&App{
db_handle: pool
}, 8080)
}
If you don't use the default number of workers (nr_workers) you have to change
it to the same number in vweb.run_at as in vweb.database_pool
Extending the App struct with [vweb_global]
You can change your App struct however you like, but there are some things you
have to keep in mind. Under the hood at each request a new instance of App is
constructed, and all fields are re-initialized with their default type values,
except for the db field.
This behaviour ensures that each request is treated equally and in the same context, but
problems arise when we want to provide more context than just the default vweb.Context.
Let's view the following example where we want to provide a secret token to our app:
module main
import vweb
struct App {
vweb.Context
secret string
}
fn main() {
vweb.run(&App{
secret: 'my secret'
}, 8080)
}
fn (mut app App) index() vweb.Result {
return app.text('My secret is: ${app.secret}')
}
When you visit localhost:8080/ you would expect to see the text
"My secret is: my secret", but instead there is only the text
"My secret is: ". This is because of the way vweb works. We can override the default
behaviour by adding the attribute [vweb_global] to the secret field.
Example:
struct App {
vweb.Context
secret string [vweb_global]
}
Now if you visit localhost:8080/ you see the text "My secret is: my secret".
Note
: the value of
secretgets initialized with the provided value when creatingApp. If you would modifysecretin one request the value won't be changed in the next request. You can use shared fields for this.
Shared Objects across requests
We saw in the previous section that we can persist data across multiple requests,
but what if we want to be able to mutate the data? Since vweb works with threads,
we have to use shared fields.
Let's see how we can add a visitor counter to our App.
Example:
module main
import vweb
struct Counter {
pub mut:
count int
}
struct App {
vweb.Context
mut:
counter shared Counter // shared fields can only be structs, arrays or maps.
}
fn main() {
// initialize the shared object
shared counter := Counter{
count: 0
}
vweb.run(&App{
counter: counter
}, 8080)
}
fn (mut app App) index() vweb.Result {
mut count := 0
// lock the counter so we can modify it
lock app.counter {
app.counter.count += 1
count = app.counter.count
}
return app.text('Total visitors: ${count}')
}
Drawback of Shared Objects
The drawback of using shared objects is that it affects performance. In the previous example
App.counter needs to be locked each time the page is loaded if there are simultaneous
requests the next requests will have to wait for the lock to be released.
It is best practice to limit the use of shared objects as much as possible.
Controllers
Controllers can be used to split up app logic so you are able to have one struct
per "/". E.g. a struct Admin for urls starting with "/admin" and a struct Foo
for urls starting with "/foo"
Example:
module main
import vweb
struct App {
vweb.Context
vweb.Controller
}
struct Admin {
vweb.Context
}
struct Foo {
vweb.Context
}
fn main() {
mut app := &App{
controllers: [
vweb.controller('/admin', &Admin{}),
vweb.controller('/foo', &Foo{}),
]
}
vweb.run(app, 8080)
}
You can do everything with a controller struct as with a regular App struct.
The only difference being is that only the main app that is being passed to vweb.run
is able to have controllers. If you add vweb.Controller on a controller struct it
will simply be ignored.
Routing
Any route inside a controller struct is treated as a relative route to its controller namespace.
['/path']
pub fn (mut app Admin) path vweb.Result {
return app.text('Admin')
}
When we created the controller with vweb.controller('/admin', &Admin{}) we told
vweb that the namespace of that controller is "/admin" so in this example we would
see the text "Admin" if we navigate to the url "/admin/path".
Vweb doesn't support fallback routes or duplicate routes, so if we add the following route to the example the code will produce an error.
['/admin/path']
pub fn (mut app App) admin_path vweb.Result {
return app.text('Admin overwrite')
}
There will be an error, because the controller Admin handles all routes starting with
"/admin"; the method admin_path is unreachable.
Databases and [vweb_global] in controllers
Fields with [vweb_global] have to passed to each controller individually.
The db field is unique and will be treated as a vweb_global field at all times.
Example:
module main
import vweb
import db.sqlite
struct App {
vweb.Context
vweb.Controller
mut:
db sqlite.DB
}
struct Admin {
vweb.Context
mut:
db sqlite.DB
}
fn main() {
mut db := sqlite.connect('db')!
mut app := &App{
db: db
controllers: [
vweb.controller('/admin', &Admin{
db: db
}),
]
}
}
Using a database pool
Example:
module main
import vweb
import db.pg
struct App {
vweb.Context
vweb.Controller
db_handle vweb.DatabasePool[pg.DB]
mut:
db pg.DB
}
struct Admin {
vweb.Context
db_handle vweb.DatabasePool[pg.DB]
mut:
db pg.DB
}
fn get_database_connection() pg.DB {
// insert your own credentials
return pg.connect(user: 'user', password: 'password', dbname: 'database') or { panic(err) }
}
fn main() {
// create the database pool and pass our `get_database_connection` function as handler
pool := vweb.database_pool(handler: get_database_connection)
mut app := &App{
db_handle: pool
controllers: [
vweb.controller('/admin', &Admin{
db_handle: pool
}),
]
}
}
Responses
- set_status
Sets the response status Example:
['/user/get_all'; get]
pub fn (mut app App) controller_get_all_user() vweb.Result {
token := app.get_header('token')
if !token {
app.set_status(401, '')
return app.text('Not valid token')
}
response := app.service_get_all_user() or {
app.set_status(400, '')
return app.text('$err')
}
return app.json(response)
}
- html
Response HTTP_OK with payload with content-type text/html
Example:
pub fn (mut app App) html_page() vweb.Result {
return app.html('<h1>ok</h1>')
}
- text
Response HTTP_OK with payload with content-type text/plain
Example:
pub fn (mut app App) simple() vweb.Result {
return app.text('A simple result')
}
- json
Response HTTP_OK with payload with content-type application/json
Examples:
['/articles'; get]
pub fn (mut app App) articles() vweb.Result {
articles := app.find_all_articles()
json_result := json.encode(articles)
return app.json(json_result)
}
['/user/create'; post]
pub fn (mut app App) controller_create_user() vweb.Result {
body := json.decode(User, app.req.data) or {
app.set_status(400, '')
return app.text('Failed to decode json, error: $err')
}
response := app.service_add_user(body.username, body.password) or {
app.set_status(400, '')
return app.text('error: $err')
}
return app.json(response)
}
- json_pretty
Response HTTP_OK with a pretty-printed JSON result Example:
fn (mut app App) time_json_pretty() {
app.json_pretty({
'time': time.now().format()
})
}
- file
Response HTTP_OK with file as payload
- ok
Response HTTP_OK with payload Example:
['/form_echo'; post]
pub fn (mut app App) form_echo() vweb.Result {
app.set_content_type(app.req.header.get(.content_type) or { '' })
return app.ok(app.form['foo'])
}
- server_error
Response a server error Example:
fn (mut app App) sse() vweb.Result {
return app.server_error(501)
}
- not_found
Response HTTP_NOT_FOUND with payload Example:
['/:user/:repo/settings']
pub fn (mut app App) user_repo_settings(username string, repository string) vweb.Result {
if username !in known_users {
return app.not_found()
}
return app.html('username: $username | repository: $repository')
}
Requests
- get_header
Returns the header data from the key Example:
['/user/get_all'; get]
pub fn (mut app App) controller_get_all_user() vweb.Result {
token := app.get_header('token')
return app.text(token)
}
- get_cookie
Sets a cookie Example:
pub fn (mut app App) before_request() {
app.user_id = app.get_cookie('id') or { '0' }
}
- add_header
Adds an header to the response with key and val Example:
['/upload'; post]
pub fn (mut app App) upload() vweb.Result {
fdata := app.files['upfile']
data_rows := fdata[0].data.split('\n')
mut output_data := ''
for elem in data_rows {
delim_row := elem.split('\t')
output_data += '${delim_row[0]}\t${delim_row[1]}\t'
output_data += '${delim_row[0].int() + delim_row[1].int()}\n'
}
output_data = output_data.all_before_last('\n')
app.add_header('Content-Disposition', 'attachment; filename=results.txt')
app.send_response_to_client('application/octet-stream', output_data)
return $vweb.html()
}
- set_cookie
Sets a cookie Example:
pub fn (mut app App) cookie() vweb.Result {
app.set_cookie(name: 'cookie', value: 'test')
return app.text('Response Headers\n$app.header')
}
- set_cookie_with_expire_date
Sets a cookie with a expire_data
Example:
pub fn (mut app App) cookie() vweb.Result {
key := 'cookie'
value := 'test'
duration := time.Duration(2 * time.minute ) // add 2 minutes
expire_date := time.now().add(duration)
app.set_cookie_with_expire_date(key, value, expire_date)
return app.text('Response Headers\n$app.header')
}
- set_content_type
Sets the response content type Example:
['/form_echo'; post]
pub fn (mut app App) form_echo() vweb.Result {
app.set_content_type(app.req.header.get(.content_type) or { '' })
return app.ok(app.form['foo'])
}
Template
-handle_static
handle_static is used to mark a folder (relative to the current working folder) as one that contains only static resources (css files, images etc).
If root is set the mount path for the dir will be in '/'
Example:
fn main() {
mut app := &App{}
app.serve_static('/favicon.ico', 'favicon.ico')
// Automatically make available known static mime types found in given directory.
os.chdir(os.dir(os.executable()))?
app.handle_static('assets', true)
vweb.run(app, port)
}
-mount_static_folder_at
makes all static files in directory_path and inside it, available at http://server/mount_path.
For example: suppose you have called .mount_static_folder_at('/var/share/myassets', '/assets'), and you have a file /var/share/myassets/main.css . => That file will be available at URL: http://server/assets/main.css .
-serve_static
Serves a file static.
url is the access path on the site, file_path is the real path to the file, mime_type is the
file type
Example:
fn main() {
mut app := &App{}
app.serve_static('/favicon.ico', 'favicon.ico')
app.mount_static_folder_at(os.resource_abs_path('.'), '/')
vweb.run(app, 8081)
}
Others
-ip
Returns the ip address from the current user
Example:
pub fn (mut app App) ip() vweb.Result {
ip := app.ip()
return app.text('ip: $ip')
}
-error
Set a string to the form error
Example:
pub fn (mut app App) error() vweb.Result {
app.error('here as an error')
println(app.form_error) //'vweb error: here as an error'
}
Cross-Site Request Forgery (CSRF) protection
Vweb has built-in csrf protection. Go to the csrf module to learn how you can protect your app against CSRF.