Struct Transaction

pub struct Transaction<'t, S> { /* private fields */ }

Transaction can be used to query the database.

From the perspective of a Transaction each TransactionMut is fully applied or not at all. Futhermore, the effects of TransactionMuts have a global order. So if we have mutations A and then B, it is impossible for a Transaction to see the effect of B without seeing the effect of A.

All TableRow references retrieved from the database live for at most 'a. This makes these references effectively local to this Transaction.

Implementations

impl<'t, S> Transaction<'t, S>

pub fn query<F, R>(&self, f: F) -> R

where F: for<'inner> FnOnce(&mut Query<'t, 'inner, S>) -> R,

Execute a query with multiple results.

let user_names = txn.query(|rows| {
    let user = rows.join(User);
    rows.into_vec(user.name())
});
assert_eq!(user_names, vec!["Alice".to_owned()]);

pub fn query_one<'e, O>(&self, val: impl IntoSelect<'t, 't, S, Out = O>) -> O

Retrieve a single result from the database.

let res = txn.query_one("test".into_expr());
assert_eq!(res, "test");

Instead of using Self::query_one in a loop, it is better to call Self::query and return all results at once.