mirror of
https://github.com/actix/actix-website
synced 2024-11-24 16:52:59 +01:00
133 lines
3.7 KiB
Markdown
133 lines
3.7 KiB
Markdown
---
|
|
title: Databases
|
|
menu: docs_patterns
|
|
weight: 1010
|
|
---
|
|
|
|
# Diesel
|
|
|
|
At the moment, Diesel 1.0 does not support asynchronous operations,
|
|
but it's possible to use the `actix` synchronous actor system as a database interface api.
|
|
|
|
Technically, sync actors are worker style actors. Multiple sync actors
|
|
can be run in parallel and process messages from same queue. Sync actors work in mpsc mode.
|
|
|
|
Let's create a simple database api that can insert a new user row into a SQLite table.
|
|
We must define a sync actor and a connection that this actor will use. The same approach
|
|
can be used for other databases.
|
|
|
|
```rust
|
|
use actix::prelude::*;
|
|
|
|
struct DbExecutor(SqliteConnection);
|
|
|
|
impl Actor for DbExecutor {
|
|
type Context = SyncContext<Self>;
|
|
}
|
|
```
|
|
|
|
This is the definition of our actor. Now, we must define the *create user* message and response.
|
|
|
|
```rust
|
|
struct CreateUser {
|
|
name: String,
|
|
}
|
|
|
|
impl Message for CreateUser {
|
|
type Result = Result<User, Error>;
|
|
}
|
|
```
|
|
|
|
We can send a `CreateUser` message to the `DbExecutor` actor, and as a result, we will receive a
|
|
`User` model instance. Next, we must define the handler implementation for this message.
|
|
|
|
```rust
|
|
impl Handler<CreateUser> for DbExecutor {
|
|
type Result = Result<User, Error>;
|
|
|
|
fn handle(&mut self, msg: CreateUser, _: &mut Self::Context) -> Self::Result
|
|
{
|
|
use self::schema::users::dsl::*;
|
|
|
|
// Create insertion model
|
|
let uuid = format!("{}", uuid::Uuid::new_v4());
|
|
let new_user = models::NewUser {
|
|
id: &uuid,
|
|
name: &msg.name,
|
|
};
|
|
|
|
// normal diesel operations
|
|
diesel::insert_into(users)
|
|
.values(&new_user)
|
|
.execute(&self.0)
|
|
.expect("Error inserting person");
|
|
|
|
let mut items = users
|
|
.filter(id.eq(&uuid))
|
|
.load::<models::User>(&self.0)
|
|
.expect("Error loading person");
|
|
|
|
Ok(items.pop().unwrap())
|
|
}
|
|
}
|
|
```
|
|
|
|
That's it! Now, we can use the *DbExecutor* actor from any http handler or middleware.
|
|
All we need is to start *DbExecutor* actors and store the address in a state where http handler
|
|
can access it.
|
|
|
|
```rust
|
|
/// This is state where we will store *DbExecutor* address.
|
|
struct State {
|
|
db: Addr<Syn, DbExecutor>,
|
|
}
|
|
|
|
fn main() {
|
|
let sys = actix::System::new("diesel-example");
|
|
|
|
// Start 3 parallel db executors
|
|
let addr = SyncArbiter::start(3, || {
|
|
DbExecutor(SqliteConnection::establish("test.db").unwrap())
|
|
});
|
|
|
|
// Start http server
|
|
HttpServer::new(move || {
|
|
App::with_state(State{db: addr.clone()})
|
|
.resource("/{name}", |r| r.method(Method::GET).a(index))})
|
|
.bind("127.0.0.1:8080").unwrap()
|
|
.start().unwrap();
|
|
|
|
println!("Started http server: 127.0.0.1:8080");
|
|
let _ = sys.run();
|
|
}
|
|
```
|
|
|
|
We will use the address in a request handler. The handle returns a future object;
|
|
thus, we receive the message response asynchronously.
|
|
`Route::a()` must be used for async handler registration.
|
|
|
|
|
|
```rust
|
|
/// Async handler
|
|
fn index(req: HttpRequest<State>) -> Box<Future<Item=HttpResponse, Error=Error>> {
|
|
let name = &req.match_info()["name"];
|
|
|
|
// Send message to `DbExecutor` actor
|
|
req.state().db.send(CreateUser{name: name.to_owned()})
|
|
.from_err()
|
|
.and_then(|res| {
|
|
match res {
|
|
Ok(user) => Ok(HttpResponse::Ok().json(user)),
|
|
Err(_) => Ok(HttpResponse::InternalServerError().into())
|
|
}
|
|
})
|
|
.responder()
|
|
}
|
|
```
|
|
|
|
> A full example is available in the
|
|
> [examples directory](https://github.com/actix/examples/tree/master/diesel/).
|
|
|
|
> More information on sync actors can be found in the
|
|
> [actix documentation](https://docs.rs/actix/0.5.0/actix/sync/index.html).
|