Struct diesel::connection::statement_cache::StatementCache

pub struct StatementCache<DB: Backend, Statement> { /* private fields */ }

A prepared statement cache

Implementations

impl<DB, Statement> StatementCache<DB, Statement>

where DB: Backend, DB::TypeMetadata: Clone, DB::QueryBuilder: Default, StatementCacheKey<DB>: Hash + Eq,

pub fn new() -> Self

Create a new prepared statement cache

pub fn len(&self) -> usize

Get the current length of the statement cache

pub fn cached_statement<T, F>( &mut self, source: &T, backend: &DB, bind_types: &[DB::TypeMetadata], prepare_fn: F, instrumentation: &mut dyn Instrumentation, ) -> QueryResult<MaybeCached<'_, Statement>>

where T: QueryFragment<DB> + QueryId, F: FnMut(&str, PrepareForCache) -> QueryResult<Statement>,

Prepare a query as prepared statement

This functions returns a prepared statement corresponding to the query passed as source with the bind values passed as bind_types. If the query is already cached inside this prepared statement cache the cached prepared statement will be returned, otherwise prepare_fn will be called to create a new prepared statement for this query source. The first parameter of the callback contains the query string, the second parameter indicates if the constructed prepared statement will be cached or not. See the module documentation for details about which statements are cached and which are not cached.