planetscale-driver 0.3.0

# PlanetScale Serverless Driver for Rust™

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Rust "version" of [database-js](https://github.com/planetscale/database-js). As stated in database-js it uses PlanetScale HTTP api for database queries.
It will run perfectly run on Cloudflare Workers Or Vercel Edge Functions.

## Usage
```bash
cargo add planetscale-driver
# also "cargo add anyhow"
```

Then proceed like in examples!

## Examples
### Connection and simple SQL execution
```rust
use planetscale_driver::PSConnection;

let mut conn = PSConnection::new(
  "<host>",
  "<user>",
  "<password>",
);
    
let res = conn.execute("SELECT 1").await.unwrap();
```

### fetch_one/fetch_all/fetch_scalar
As you can see, deserialization doesn't use field names (MAYBE IN FUTURE) so remember to write your structs correctly!

```rust
use planetscale_driver::{Database, Deserializer, query};

#[derive(Database, Debug)]
struct TestD {
  val: u32
}

// ...

let res: TestD = query("SELECT 1").fetch_one(&mut conn).await?;
println!("{:?}", res);

let res: Vec<TestD> = query("SELECT val FROM testds").fetch_all(&mut conn).await?;
println!("{:?}", res);

let res: bool = query("SELECT true").fetch_scalar(&mut conn).await?;
println!("{:?}", res);
```

### QueryBuilder
If you want to bind safely values into your query, you should use QueryBuilder

Note: now query method is wrapper around QueryBuilder

```rust
// ...

// note: values passed to .bind function must have trait ToString 
let id = 69;
let name = "420";

// res there will be empty result, if you want to get reponse data use "execute_raw"
let res = query("INSERT INTO test(id, name) VALUES($0, \"$1\")")
  .bind(id)
  .bind(name)
  .execute(&mut conn)
  .await?;
```

### Transactions
```rust
// ...

// NOTE: conn in closure isn't affecting main conn, its copied so session
// isn't modifed on "original" conn
conn.transaction(|conn| async move {
    //             ^- conn is Arc Mutex so we must do that
    //                note: it's not normal mutex (it's async mutex)
    let mut conn = conn.lock().await;

    conn.execute("QUERY")
        .await?;

    conn.execute("OTHER QUERY")
        .await?;

    //     ^- use question mark to propagate errors "up"
    //        it's required if you want to rollback changes after error

    Ok(())
}).await?;
```

### More examples in the [examples](examples) folder
If you want to run them:
```bash
PS_HOST=<host> PS_USER=<username> PS_PASS=<pscale_password> cargo run --example <example_name>
```