Lifecycle Reducers dicsonnect exmaple uses `insert` instead of `try_insert`

[CorrM]

in Lifecycle Reducers on connected example uses insert instead of try_insert:

ctx.db.sessions().insert(Session {
        connection_id: conn_id,
        identity: ctx.sender,
        connected_at: ctx.timestamp,
    })?;

the problem are ? which expect Result while insert returns the inserted row.

One more question:
session are created when client connected, and session removed when client disconnected.
what will happen if the server for any reason closed between this two events? session will get removed?

also what the schema of Session in the example? did identity or connection_id is the primary key?

[bfops]

Thank you for filing this! We'll fix the docs.

session are created when client connected, and session removed when client disconnected.
what will happen if the server for any reason closed between this two events? session will get removed?

When the server starts back up, it will call your client_disconnected reducer for every client that was still connected.

also what the schema of Session in the example? did identity or connection_id is the primary key?

See https://spacetimedb.com/docs/intro/key-architecture#connectionid for more context on the semantics of each type. In this example, making identity the primary key would cause an error if a single user tried to open multiple connections to the module. Depending on your use case, that may or may not be the behavior that you want.

[clockwork-labs-bot]

This has been fixed in the current docs. The Rust lifecycle reducer examples now use try_insert(...)?; (which returns Result) instead of insert(...)?; (which returns the row directly).

The current Rust examples correctly use:

• ctx.db.settings().try_insert(...)? in init
• ctx.db.sessions().try_insert(...)? in client_connected
• ctx.db.sessions().connection_id().delete(...) in client_disconnected

All compile correctly with the Result<(), String> return type.

[clockwork-labs-bot]

The fix was in commit c27db13 (PR #4025: Docs - insert -> try_insert).