Trait LoadConnection

pub trait LoadConnection<B = DefaultLoadingMode>: Connection {
    type Cursor<'conn, 'query>: Iterator<Item = QueryResult<<Self as LoadConnection<B>>::Row<'conn, 'query>>>
       where Self: 'conn;
    type Row<'conn, 'query>: Row<'conn, Self::Backend>
       where Self: 'conn;

    // Required method
    fn load<'conn, 'query, T>(
        &'conn mut self,
        source: T,
    ) -> QueryResult<Self::Cursor<'conn, 'query>>
       where T: Query + QueryFragment<Self::Backend> + QueryId + 'query,
             Self::Backend: QueryMetadata<T::SqlType>;
}

The specific part of a Connection which actually loads data from the database

This is a separate trait to allow connection implementations to specify different loading modes via the generic parameter.

Required Associated Types

type Cursor<'conn, 'query>: Iterator<Item = QueryResult<<Self as LoadConnection<B>>::Row<'conn, 'query>>> where Self: 'conn

The cursor type returned by LoadConnection::load

Users should handle this as opaque type that implements Iterator

type Row<'conn, 'query>: Row<'conn, Self::Backend> where Self: 'conn

The row type used as Iterator::Item for the iterator implementation of LoadConnection::Cursor

Required Methods

fn load<'conn, 'query, T>( &'conn mut self, source: T, ) -> QueryResult<Self::Cursor<'conn, 'query>>

where T: Query + QueryFragment<Self::Backend> + QueryId + 'query, Self::Backend: QueryMetadata<T::SqlType>,

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Executes a given query and returns any requested values

This function executes a given query and returns the query result as given by the database. Normal users should not use this function. Use QueryDsl::load instead.

This function is useful for people trying to build an alternative dsl on top of diesel. It returns an impl Iterator<Item = QueryResult<&impl Row<Self::Backend>>. This type can be used to iterate over all rows returned by the database.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl LoadConnection for MysqlConnection

Available on crate features mysql and mysql_backend only.

type Cursor<'conn, 'query> = StatementIterator<'conn>

type Row<'conn, 'query> = MysqlRow

impl LoadConnection for SqliteConnection

Available on crate feature sqlite only.

type Cursor<'conn, 'query> = StatementIterator<'conn, 'query>

type Row<'conn, 'query> = SqliteRow<'conn, 'query>

impl<B> LoadConnection<B> for PgConnection

where Self: PgLoadingMode<B>,

Available on crate features postgres and postgres_backend only.

type Cursor<'conn, 'query> = <PgConnection as PgLoadingMode<B>>::Cursor<'conn, 'query>

type Row<'conn, 'query> = <PgConnection as PgLoadingMode<B>>::Row<'conn, 'query>

impl<B, M> LoadConnection<B> for PooledConnection<M>

where M: ManageConnection, M::Connection: LoadConnection<B> + R2D2Connection,

Available on crate feature r2d2 only.

type Cursor<'conn, 'query> = <<M as ManageConnection>::Connection as LoadConnection<B>>::Cursor<'conn, 'query>

type Row<'conn, 'query> = <<M as ManageConnection>::Connection as LoadConnection<B>>::Row<'conn, 'query>