Updated rust quickstart for 0.12

Overview

I've upgraded the API of the example and improved the language slightly. If you have suggested edits, please use the Github feature to suggest edits so I can easily approve them.

Rendered: https://github.com/clockworklabs/spacetime-docs/blob/57ccb7a8c3bf569b775eabfb7f7f18eea5314426/docs/modules/rust/quickstart.md

I used chatgpt to follow the final tutorial and this is the module you end up with:

use spacetimedb::{table, reducer, Table, ReducerContext, Identity, Timestamp};

#[table(name = user, public)]
pub struct User {
    #[primary_key]
    identity: Identity,
    name: Option<String>,
    online: bool,
}

#[table(name = message, public)]
pub struct Message {
    sender: Identity,
    sent: Timestamp,
    text: String,
}

#[reducer]
/// Clients invoke this reducer to set their user names.
pub fn set_name(ctx: &ReducerContext, name: String) -> Result<(), String> {
    let name = validate_name(name)?;
    if let Some(user) = ctx.db.user().identity().find(ctx.sender) {
        ctx.db.user().identity().update(User { name: Some(name), ..user });
        Ok(())
    } else {
        Err("Cannot set name for unknown user".to_string())
    }
}

/// Takes a name and checks if it's acceptable as a user's name.
fn validate_name(name: String) -> Result<String, String> {
    if name.is_empty() {
        Err("Names must not be empty".to_string())
    } else {
        Ok(name)
    }
}

#[reducer]
/// Clients invoke this reducer to send messages.
pub fn send_message(ctx: &ReducerContext, text: String) -> Result<(), String> {
    let text = validate_message(text)?;
    log::info!("{}", text);
    ctx.db.message().insert(Message {
        sender: ctx.sender,
        text,
        sent: ctx.timestamp,
    });
    Ok(())
}

/// Takes a message's text and checks if it's acceptable to send.
fn validate_message(text: String) -> Result<String, String> {
    if text.is_empty() {
        Err("Messages must not be empty".to_string())
    } else {
        Ok(text)
    }
}

#[reducer(client_connected)]
// Called when a client connects to the SpacetimeDB
pub fn client_connected(ctx: &ReducerContext) {
    if let Some(user) = ctx.db.user().identity().find(ctx.sender) {
        // If this is a returning user, i.e. we already have a `User` with this `Identity`,
        // set `online: true`, but leave `name` and `identity` unchanged.
        ctx.db.user().identity().update(User { online: true, ..user });
    } else {
        // If this is a new user, create a `User` row for the `Identity`,
        // which is online, but hasn't set a name.
        ctx.db.user().insert(User {
            name: None,
            identity: ctx.sender,
            online: true,
        });
    }
}

#[reducer(client_disconnected)]
// Called when a client disconnects from SpacetimeDB
pub fn identity_disconnected(ctx: &ReducerContext) {
    if let Some(user) = ctx.db.user().identity().find(ctx.sender) {
        ctx.db.user().identity().update(User { online: false, ..user });
    } else {
        // This branch should be unreachable,
        // as it doesn't make sense for a client to disconnect without connecting first.
        log::warn!("Disconnect event for unknown user with identity {:?}", ctx.sender);
    }
}

clockworklabs / spacetime-docs

Updated rust quickstart for 0.12 #88

Overview