393 lines
8.4 KiB
Markdown
393 lines
8.4 KiB
Markdown
## Building a 150 KB web blog in V with 0 dependencies
|
|
|
|
Hello,
|
|
|
|
In this guide we'll build a simple web blog in V.
|
|
|
|
The benefits of using V for web:
|
|
- A safe, fast, language with the development speed of Python and
|
|
the performance of C.
|
|
- Zero dependencies: everything you need for web development comes with the language
|
|
in a 1 MB package.
|
|
- Very small resulting binaries: the blog we'll create in this tutorial is about 150 KB.
|
|
- Easy deployments: a single binary file that even includes the precompiled templates.
|
|
- Runs on the cheapest hardware with minimum footprint: for most apps a $3 instance
|
|
is enough.
|
|
- Fast development without any boilerplate.
|
|
|
|
*Please note that V and Vweb are at a very early stage and are changing rapidly.*
|
|
|
|
The code is available <a href='https://github.com/vlang/v/tree/master/tutorials/code/blog'>here</a>.
|
|
|
|
|
|
### Installing V
|
|
|
|
```
|
|
wget https://github.com/vlang/v/releases/latest/download/v_linux.zip
|
|
unzip v_linux.zip
|
|
cd v
|
|
sudo ./v symlink
|
|
```
|
|
|
|
Now V should be globally available on your system.
|
|
|
|
> On macOS use `v_macos.zip`, on Windows - `v_windows.zip`.
|
|
If you use a BSD system, Solaris, Android, or simply want to install V
|
|
from source, follow the simple instructions here:
|
|
https://github.com/vlang/v#installing-v-from-source
|
|
|
|
|
|
### Creating a new Vweb project
|
|
|
|
V projects can be created anywhere and don't need to have a certain structure:
|
|
|
|
```bash
|
|
mkdir blog
|
|
cd blog
|
|
touch blog.v
|
|
```
|
|
|
|
First let's create a simple hello world website:
|
|
|
|
```v
|
|
// blog.v
|
|
module main
|
|
|
|
import (
|
|
vweb
|
|
)
|
|
|
|
pub struct App {
|
|
mut:
|
|
vweb vweb.Context
|
|
}
|
|
|
|
fn main() {
|
|
vweb.run<App>(8080)
|
|
}
|
|
|
|
fn (app mut App) index() {
|
|
app.vweb.text('Hello, world from vweb!')
|
|
}
|
|
|
|
pub fn (app &App) init() {}
|
|
pub fn (app &App) reset() {}
|
|
|
|
```
|
|
|
|
Run it with
|
|
|
|
```bash
|
|
v run blog.v
|
|
```
|
|
|
|
```
|
|
Running a Vweb app on http://localhost:8080 ...
|
|
```
|
|
|
|
Vweb helpfully provided a link, open http://localhost:8080/ in your browser:
|
|
|
|
<img width=662 src="https://github.com/vlang/v/blob/master/tutorials/img/hello.png?raw=true">
|
|
|
|
The `App` struct is an entry point of our web application. If you have experience
|
|
with an MVC web framework, you can think of it as a controller. (Vweb is
|
|
not an MVC framework however.)
|
|
|
|
As you can see, there are no routing rules. The `index()` action handles the `/` request by default.
|
|
Vweb often uses convention over configuration, and adding a new action requires
|
|
no routing rules either:
|
|
|
|
```v
|
|
fn (app mut App) time() {
|
|
app.vweb.text(time.now().format())
|
|
}
|
|
```
|
|
|
|
|
|
<img width=662 src="https://github.com/vlang/v/blob/master/tutorials/img/time.png?raw=true">
|
|
|
|
>You have to rebuild and restart the website every time you change the code.
|
|
In the future Vweb will detect changes and recompile the website in the background
|
|
while it's running.
|
|
|
|
The `.text(string)` method obviously returns a plain text document with the provided
|
|
text, which isn't frequently used in websites.
|
|
|
|
|
|
### HTML View
|
|
|
|
|
|
Let's return an HTML view instead. Create `index.html` in the same directory:
|
|
|
|
```html
|
|
<html>
|
|
<header>
|
|
<title>V Blog</title>
|
|
</header>
|
|
<body>
|
|
<b>@message</b>
|
|
<br>
|
|
<img src='https://vlang.io/img/v-logo.png' width=100>
|
|
</body>
|
|
</html>
|
|
```
|
|
|
|
and update our `index()` action so that it returns the HTML view we just created:
|
|
|
|
```v
|
|
fn (app mut App) index() {
|
|
message := 'Hello, world from Vweb!'
|
|
$vweb.html()
|
|
}
|
|
```
|
|
|
|
<img width=662 src="https://github.com/vlang/v/blob/master/tutorials/img/hello_html.png?raw=true">
|
|
|
|
Good, now we have an actual HTML page.
|
|
|
|
The V template language is similar to C#'s Razor: `@message` prints the value
|
|
of `message`.
|
|
|
|
You may notice something unusual: the `message` variable created in the `index()`
|
|
action is automatically available in the view.
|
|
|
|
It's another feature of Vweb to reduce the boilerplate in your web apps.
|
|
No need to create view models just to pass data, or use an unsafe and untyped
|
|
alternative, like C#'s `ViewBag["message"]`.
|
|
|
|
Making all action's variables available in the view may seem crazy,
|
|
but V is a language with pure functions by default, and you won't be able
|
|
to modify any data from a view. `<b>@foo.bar()</b>` will only work if the `bar()` method
|
|
doesn't modify `foo`.
|
|
|
|
The HTML template is compiled to V during the compilation of the website, that's done by the `$vweb.html()` line.
|
|
(`$` always means compile time actions in V.) offering the following benefits:
|
|
|
|
- Great performance, since the templates don't need to be compiled
|
|
on every request, like in almost every major web framework.
|
|
|
|
- Easier deployment, since all your HTML templates are compiled
|
|
into a single binary file together with the web application itself.
|
|
|
|
- All errors in the templates are guaranteed to be caught during compilation.
|
|
|
|
### Fetching data with V ORM
|
|
|
|
Now let's display some articles!
|
|
|
|
We'll be using V's builtin ORM and a Postgres database. (V ORM will also
|
|
support MySQL, SQLite, and SQL Server in the near future.)
|
|
|
|
Create a SQL file with the schema:
|
|
```sql
|
|
create database blog;
|
|
|
|
\c blog
|
|
|
|
drop table articles;
|
|
|
|
create table articles (
|
|
id serial primary key,
|
|
title text default '',
|
|
text text default ''
|
|
);
|
|
|
|
insert into articles (title, text) values (
|
|
'Hello, world!',
|
|
'V is great.'
|
|
);
|
|
|
|
insert into articles (title, text) values (
|
|
'Second post.',
|
|
'Hm... what should I write about?'
|
|
);
|
|
```
|
|
|
|
Run the file with `psql -f blog.sql`.
|
|
|
|
|
|
Add a Postgres DB handle to `App`:
|
|
|
|
```v
|
|
struct App {
|
|
mut:
|
|
vweb vweb.Context
|
|
db pg.DB
|
|
}
|
|
```
|
|
|
|
|
|
|
|
Modify the `init()` method we created earlier to connect to a database:
|
|
|
|
```v
|
|
pub fn (app mut App) init() {
|
|
db := pg.connect(pg.Config{
|
|
host: '127.0.0.1'
|
|
dbname: 'blog'
|
|
user: 'blog'
|
|
}) or { panic(err) }
|
|
app.db = db
|
|
}
|
|
```
|
|
|
|
Code in the `init()` function is run only once during app's startup, so we are going
|
|
to have one DB connection for all requests.
|
|
|
|
Create a new file `article.v`:
|
|
|
|
|
|
```v
|
|
|
|
module main
|
|
|
|
struct Article {
|
|
id int
|
|
title string
|
|
text string
|
|
}
|
|
|
|
pub fn (app &App) find_all_articles() []Article {
|
|
db := app.db
|
|
articles := db.select from Article
|
|
return articles
|
|
}
|
|
```
|
|
|
|
Let's fetch the articles in the `index()` action:
|
|
|
|
```v
|
|
fn (app &App) index() {
|
|
articles := app.find_all_articles()
|
|
$vweb.html()
|
|
}
|
|
```
|
|
|
|
|
|
Finally, let's update our view:
|
|
|
|
```html
|
|
<body>
|
|
@for article in articles
|
|
<div>
|
|
<b>@article.title</b> <br>
|
|
@article.text
|
|
</div>
|
|
@end
|
|
</body>
|
|
```
|
|
|
|
```bash
|
|
v run .
|
|
```
|
|
|
|
<img width=662 src="https://github.com/vlang/v/blob/master/tutorials/img/articles1.png?raw=true">
|
|
|
|
That was very simple, wasn't it?
|
|
|
|
The built-in V ORM uses a syntax very similar to SQL. The queries are built with V.
|
|
For example, if we only wanted to find articles with ids between 100 and 200, we'd do:
|
|
|
|
```
|
|
articles := db.select from Article where id >= 100 && id <= 200
|
|
```
|
|
|
|
Retrieving a single article is very simple:
|
|
|
|
```v
|
|
|
|
pub fn (app &App) retrieve_article() ?Article {
|
|
db := app.db
|
|
article := db.select from Article limit 1
|
|
return article
|
|
}
|
|
```
|
|
|
|
V ORM uses V's optionals for single values, which is very useful, since
|
|
bad queries will always be handled by the developer:
|
|
|
|
```v
|
|
article := app.retrieve_article(10) or {
|
|
app.vweb.text('Article not found')
|
|
return
|
|
}
|
|
```
|
|
|
|
|
|
> `db := app.db` is a temporary limitation in the
|
|
V ORM, soon this will not be needed.
|
|
|
|
|
|
### Adding new articles
|
|
|
|
Create `new.html`:
|
|
|
|
```html
|
|
<html>
|
|
<header>
|
|
<title>V Blog</title>
|
|
</header>
|
|
<body>
|
|
<form action='/new_article' method='post'>
|
|
<input type='text' placeholder='Title' name='title'> <br>
|
|
<textarea placeholder='Text' name='text'></textarea>
|
|
<input type='submit'>
|
|
</form>
|
|
</body>
|
|
</html>
|
|
```
|
|
|
|
```v
|
|
pub fn (app mut App) new_article() {
|
|
title := app.vweb.form['title']
|
|
text := app.vweb.form['text']
|
|
if title == '' || text == '' {
|
|
app.vweb.text('Empty text/title')
|
|
return
|
|
}
|
|
article := Article{
|
|
title: title
|
|
text: text
|
|
}
|
|
db := app.db
|
|
db.insert(article)
|
|
app.vweb.redirect('/article/')
|
|
}
|
|
```
|
|
|
|
> Untyped `form['key']` is temporary. Very soon Vweb will accept query and form
|
|
parameters via function arguments: `new_article(title, text string) {`.
|
|
|
|
We need to update `index.html` to add a link to the "new article" page:
|
|
|
|
```html
|
|
<a href='/new'>New article</a>
|
|
```
|
|
|
|
|
|
|
|
### JSON endpoints
|
|
|
|
This tutorial used the traditional server side rendering. If you prefer
|
|
to render everything on the client or need an API, creating JSON endpoints
|
|
in V is very simple:
|
|
|
|
```v
|
|
pub fn (app mut App) articles() {
|
|
articles := app.find_all_articles()
|
|
app.vweb.json(json.encode(articles))
|
|
}
|
|
```
|
|
|
|
<img width=662 src="https://github.com/vlang/v/blob/master/tutorials/img/articles_json.png?raw=true">
|
|
|
|
|
|
|
|
To be continued...
|
|
|
|
For an example of a more sophisticated web app written in V, check out Vorum: https://github.com/vlang/vorum
|
|
|
|
|
|
|
|
|