Rust SDK (alpha)

cargo add powersync

// MyBackendConnector is defined in the next step...
db.connect(SyncOptions::new(MyBackendConnector {
    db: db.clone(),
})).await;

struct MyBackendConnector {
    db: PowerSyncDatabase,
}

#[async_trait]
impl BackendConnector for MyBackendConnector {
    async fn fetch_credentials(&self) -> Result<PowerSyncCredentials, PowerSyncError> {
        // implement fetchCredentials to obtain the necessary credentials to connect to your backend
        // See an example implementation in https://github.com/powersync-ja/powersync-native/blob/508193b0822b8dad1a534a16462e2fcd36a9ac68/examples/egui_todolist/src/database.rs#L119-L133

        Ok(PowerSyncCredentials {
            endpoint: "[Your PowerSync instance URL or self-hosted endpoint]".to_string(),
            // Use a development token (see Authentication Setup https://docs.powersync.com/configuration/auth/development-tokens) to get up and running quickly
            token: "An authentication token".to_string(),
        })
    }

    async fn upload_data(&self) -> Result<(), PowerSyncError> {
        // Implement uploadData to send local changes to your backend service
        // You can omit this method if you only want to sync data from the server to the client
        // See an example implementation under Usage Examples (sub-page)
        // See https://docs.powersync.com/handling-writes/writing-client-changes for considerations.
        let  mut local_writes = self.db.crud_transactions();
        while let Some(tx) = local_writes.try_next().await? {
            todo!("Inspect tx.crud for local writes that need to be uploaded to your backend");
            tx.complete().await?;
        }

        Ok(())
    }
}

use serde_json::json;

// Subscribe to a stream with parameters
let sub = db
    .sync_stream("list_todos", Some(&json!({ "list_id": "abc123" })))
    .subscribe()
    .await?;

// Wait for the initial data to sync
sub.wait_for_first_sync().await;

// The stream's rows are now in the local SQLite database.
// TODO: Read the todos for this list with a local query.

// When the data is no longer needed.
// Dropping the subscription handle has the same effect.
sub.unsubscribe();

async fn find(db: &PowerSyncDatabase, id: &str) -> Result<(), PowerSyncError> {
    let reader = db.reader().await?;
    let mut stmt = reader.prepare("SELECT * FROM lists WHERE id = ?")?;
    let mut rows = stmt.query(params![id])?;
    while let Some(row) = rows.next()? {
        let id: String = row.get("id")?;
        let name: String = row.get("name")?;

        println!("Found todo list: {id}, {name}");
    }
    Ok(())
}

async fn watch_pending_lists(db: &PowerSyncDatabase) -> Result<(), PowerSyncError> {
    let stream = db.watch_statement(
        "SELECT * FROM lists WHERE state = ?".to_string(),
        params!["pending"],
        |stmt, params| {
            let mut rows = stmt.query(params)?;
            let mut mapped = vec![];

            while let Some(row) = rows.next()? {
                mapped.push(() /* TODO: Read row into list struct */)
            }

            Ok(mapped)
        },
    );
    let mut stream = pin!(stream);

    // Note: The stream is never-ending, so you probably want to call this in an independent async
    // task.
    while let Some(event) = stream.try_next().await? {
        // Update UI to display rows
    }
    Ok(())
}

async fn insert_customer(
    db: &PowerSyncDatabase,
    name: &str,
    email: &str,
) -> Result<(), PowerSyncError> {
    let writer = db.writer().await?;
    writer.execute(
        "INSERT INTO customers (id, name, email) VALUES (uuid(), ?, ?)",
        params![name, email],
    )?;
    Ok(())
}

fn main() {
    env_logger::init();
    // ...
}