Access Permissions

SpacetimeDB enforces different levels of table access depending on the context. All contexts access tables through ctx.db, but the available operations differ based on whether the context is read-write or read-only.

Reducers - Read-Write Access

Reducers receive a ReducerContext which provides full read-write access to tables. They can perform all CRUD operations: insert, read, update, and delete.

Rust

#[spacetimedb::reducer]
fn example(ctx: &ReducerContext) -> Result<(), String> {
    // Insert
    ctx.db.user().insert(User {
        id: 0,
        name: "Alice".to_string(),
        email: "alice@example.com".to_string(),
    });

    // Read: iterate all rows
    for user in ctx.db.user().iter() {
        log::info!("User: {}", user.name);
    }

    // Read: find by unique column
    if let Some(mut user) = ctx.db.user().id().find(123) {
        // Update
        user.name = "Bob".to_string();
        ctx.db.user().id().update(user);
    }

    // Delete
    ctx.db.user().id().delete(456);

    Ok(())
}

C#

[SpacetimeDB.Reducer]
public static void Example(ReducerContext ctx)
{
    // Insert
    ctx.Db.User.Insert(new User { Id = 0, Name = "Alice", Email = "alice@example.com" });

    // Read: iterate all rows
    foreach (var user in ctx.Db.User.Iter())
    {
        Log.Info($"User: {user.Name}");
    }

    // Read: find by unique column
    if (ctx.Db.User.Id.Find(123) is User foundUser)
    {
        // Update
        foundUser.Name = "Bob";
        ctx.Db.User.Id.Update(foundUser);
    }

    // Delete
    ctx.Db.User.Id.Delete(456);
}

TypeScript

spacetimedb.reducer('example', {}, (ctx) => {
  // Insert
  ctx.db.user.insert({ id: 0, name: 'Alice', email: 'alice@example.com' });

  // Read: iterate all rows
  for (const user of ctx.db.user.iter()) {
    console.log(user.name);
  }

  // Read: find by unique column
  const foundUser = ctx.db.user.id.find(123);
  if (foundUser) {
    // Update
    foundUser.name = 'Bob';
    ctx.db.user.id.update(foundUser);
  }

  // Delete
  ctx.db.user.id.delete(456);
});

Procedures with Transactions - Read-Write Access

Procedures receive a ProcedureContext and can access tables through transactions. Unlike reducers, procedures must explicitly open a transaction to read from or modify the database.

Rust

#[spacetimedb::procedure]
fn update_user_procedure(ctx: &mut ProcedureContext, user_id: u64, new_name: String) {
    // Must explicitly open a transaction
    ctx.with_tx(|ctx| {
        // Full read-write access within the transaction
        if let Some(mut user) = ctx.db.user().id().find(user_id) {
            user.name = new_name.clone();
            ctx.db.user().id().update(user);
        }
    });
    // Transaction is committed when the closure returns
}

C#

Support for procedures in C# modules is coming soon!

TypeScript

spacetimedb.procedure('updateUserProcedure', { userId: t.u64(), newName: t.string() }, t.unit(), (ctx, { userId, newName }) => {
  // Must explicitly open a transaction
  ctx.withTx(ctx => {
    // Full read-write access within the transaction
    const user = ctx.db.user.id.find(userId);
    if (user) {
      user.name = newName;
      ctx.db.user.id.update(user);
    }
  });
  // Transaction is committed when the function returns
  return {};
});

See the Procedures documentation for more details on using procedures, including making HTTP requests to external services.

Views - Read-Only Access

Views receive a ViewContext or AnonymousViewContext which provides read-only access to tables. They can query and iterate tables, but cannot insert, update, or delete rows.

Rust

#[spacetimedb::view(name = find_users_by_name, public)]
fn find_users_by_name(ctx: &ViewContext) -> Vec<User> {
    // Can read and filter
    ctx.db.user().name().filter("Alice").collect()

    // Cannot insert, update, or delete
    // ctx.db.user().insert(...) // ❌ Compile error
}

C#

[SpacetimeDB.View(Name = "FindUsersByName", Public = true)]
public static List<User> FindUsersByName(ViewContext ctx)
{
    // Can read and filter
    return ctx.Db.User.Name.Filter("Alice").ToList();
    
    // Cannot insert, update, or delete
    // ctx.Db.user.Insert(...) // ❌ Method not available
}

TypeScript

spacetimedb.view(
  { name: 'findUsersByName', public: true },
  t.array(user.rowType),
  (ctx) => {
    // Can read and filter
    return Array.from(ctx.db.user.name.filter('Alice'));

    // Cannot insert, update, or delete
    // ctx.db.user.insert(...) // ❌ Method not available
  });

Client Access - Read-Only Access

Clients connect to databases and can access public tables through subscriptions and queries. See the Subscriptions documentation for details on client-side table access.