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 (mut app App) time() vweb.Result {
app.vweb.text(time.now().format())
return vweb.Result{}
}
```
>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 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
```
and update our `index()` action so that it returns the HTML view we just created:
```v
pub fn (mut app App) index() vweb.Result {
message := 'Hello, world from Vweb!'
return $vweb.html()
}
```
Good, now we have an actual HTML page.
The V template language is similar to C#'s Razor: `@message` prints the value
of `message`.
You may notice something unusual: the `message` variable created in the `index()`
action is automatically available in the view.
It's another feature of Vweb to reduce the boilerplate in your web apps.
No need to create view models just to pass data, or use an unsafe and untyped
alternative, like C#'s `ViewBag["message"]`.
Making all action variables available in the view may seem crazy,
but V is a language with pure functions by default, and you won't be able
to modify any data from a view. `@foo.bar()` will only work if the `bar()` method
doesn't modify `foo`.
The HTML template is compiled to V during the compilation of the website, that's done by the `$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 SQLite database.
(V ORM will also support MySQL, Postgre, and SQL Server soon.)
Create a SQLite file with the schema:
```sql
drop table if exists Article;
create table Article (
id integer primary key,
title text default "",
text text default ""
);
insert into Article (title, text) values (
"Hello, world!",
"V is great."
);
insert into Article (title, text) values (
"Second post.",
"Hm... what should I write about?"
);
```
Run the file with `sqlite3 blog.db < blog.sqlite`.
Add a SQLite handle to `App`:
```v
import sqlite
struct App {
pub mut:
vweb vweb.Context
db sqlite.DB
}
```
Modify the `init_once()` method we created earlier to connect to a database:
```v
pub fn (mut app App) init_once() {
db := sqlite.connect(':memory:') or { panic(err) }
db.exec('create table `Article` (id integer primary key, title text default "", text text default "")')
db.exec('insert into Article (title, text) values ("Hello, world!", "V is great.")')
db.exec('insert into Article (title, text) values ("Second post.", "Hm... what should I write about?")')
app.db = db
}
```
Code in the `init_once()` 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
// article.v
module main
struct Article {
id int
title string
text string
}
pub fn (app &App) find_all_articles() []Article {
return sql app.db {
select from Article
}
}
```
Let's fetch the articles in the `index()` action:
```v
pub fn (app &App) index() vweb.Result {
articles := app.find_all_articles()
return $vweb.html()
}
```
Finally, let's update our view:
```html
@for article in articles
@article.title
@article.text
@end
```
```bash
v run .
```
@article.text
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:
```
return sql app.db {
select from Article where id >= 100 && id <= 200
}
```
Retrieving a single article is very simple:
```v
pub fn (app &App) retrieve_article() ?Article {
return sql app.db {
select from Article limit 1
}
}
```
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
}
```
### Adding new articles
Create `new.html`:
```html
To be continued...
For an example of a more sophisticated web app written in V, check out Vorum: https://github.com/vlang/vorum