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use crate::database::Database;
use crate::describe::Describe;
use crate::error::{BoxDynError, Error};
use crate::sql_str::{SqlSafeStr, SqlStr};
use either::Either;
use futures_core::future::BoxFuture;
use futures_core::stream::BoxStream;
use futures_util::{FutureExt, StreamExt, TryFutureExt, TryStreamExt};
use std::{fmt::Debug, future};
/// A type that contains or can provide a database
/// connection to use for executing queries against the database.
///
/// No guarantees are provided that successive queries run on the same
/// physical database connection.
///
/// A [`Connection`](crate::connection::Connection) is an `Executor` that guarantees that
/// successive queries are ran on the same physical database connection.
///
/// Implemented for the following:
///
/// * [`&Pool`](super::pool::Pool)
/// * [`&mut Connection`](super::connection::Connection)
///
/// The [`Executor`] impls for [`Transaction`](crate::transaction::Transaction)
/// and [`PoolConnection`](crate::pool::PoolConnection) have been deleted because they
/// cannot exist in the new crate architecture without rewriting the Executor trait entirely.
/// To fix this breakage, simply add a dereference where an impl [`Executor`] is expected, as
/// they both dereference to the inner connection type which will still implement it:
/// * `&mut transaction` -> `&mut *transaction`
/// * `&mut connection` -> `&mut *connection`
///
pub trait Executor<'c>: Send + Debug + Sized {
type Database: Database;
/// Execute the query and return the total number of rows affected.
fn execute<'e, 'q: 'e, E>(
self,
query: E,
) -> BoxFuture<'e, Result<<Self::Database as Database>::QueryResult, Error>>
where
'c: 'e,
E: 'q + Execute<'q, Self::Database>,
{
self.execute_many(query).try_collect().boxed()
}
/// Execute multiple queries and return the rows affected from each query, in a stream.
fn execute_many<'e, 'q: 'e, E>(
self,
query: E,
) -> BoxStream<'e, Result<<Self::Database as Database>::QueryResult, Error>>
where
'c: 'e,
E: 'q + Execute<'q, Self::Database>,
{
self.fetch_many(query)
.try_filter_map(|step| async move {
Ok(match step {
Either::Left(rows) => Some(rows),
Either::Right(_) => None,
})
})
.boxed()
}
/// Execute the query and return the generated results as a stream.
fn fetch<'e, 'q: 'e, E>(
self,
query: E,
) -> BoxStream<'e, Result<<Self::Database as Database>::Row, Error>>
where
'c: 'e,
E: 'q + Execute<'q, Self::Database>,
{
self.fetch_many(query)
.try_filter_map(|step| async move {
Ok(match step {
Either::Left(_) => None,
Either::Right(row) => Some(row),
})
})
.boxed()
}
/// Execute multiple queries and return the generated results as a stream
/// from each query, in a stream.
fn fetch_many<'e, 'q: 'e, E>(
self,
query: E,
) -> BoxStream<
'e,
Result<
Either<<Self::Database as Database>::QueryResult, <Self::Database as Database>::Row>,
Error,
>,
>
where
'c: 'e,
E: 'q + Execute<'q, Self::Database>;
/// Execute the query and return all the generated results, collected into a [`Vec`].
fn fetch_all<'e, 'q: 'e, E>(
self,
query: E,
) -> BoxFuture<'e, Result<Vec<<Self::Database as Database>::Row>, Error>>
where
'c: 'e,
E: 'q + Execute<'q, Self::Database>,
{
self.fetch(query).try_collect().boxed()
}
/// Execute the query and returns exactly one row.
fn fetch_one<'e, 'q: 'e, E>(
self,
query: E,
) -> BoxFuture<'e, Result<<Self::Database as Database>::Row, Error>>
where
'c: 'e,
E: 'q + Execute<'q, Self::Database>,
{
self.fetch_optional(query)
.and_then(|row| {
future::ready(match row {
Some(row) => Ok(row),
None => Err(Error::RowNotFound),
})
})
.boxed()
}
/// Execute the query and returns at most one row.
fn fetch_optional<'e, 'q: 'e, E>(
self,
query: E,
) -> BoxFuture<'e, Result<Option<<Self::Database as Database>::Row>, Error>>
where
'c: 'e,
E: 'q + Execute<'q, Self::Database>;
/// Prepare the SQL query to inspect the type information of its parameters
/// and results.
///
/// Be advised that when using the `query`, `query_as`, or `query_scalar` functions, the query
/// is transparently prepared and executed.
///
/// This explicit API is provided to allow access to the statement metadata available after
/// it prepared but before the first row is returned.
#[inline]
fn prepare<'e>(
self,
query: SqlStr,
) -> BoxFuture<'e, Result<<Self::Database as Database>::Statement, Error>>
where
'c: 'e,
{
self.prepare_with(query, &[])
}
/// Prepare the SQL query, with parameter type information, to inspect the
/// type information about its parameters and results.
///
/// Only some database drivers (PostgreSQL, MSSQL) can take advantage of
/// this extra information to influence parameter type inference.
fn prepare_with<'e>(
self,
sql: SqlStr,
parameters: &'e [<Self::Database as Database>::TypeInfo],
) -> BoxFuture<'e, Result<<Self::Database as Database>::Statement, Error>>
where
'c: 'e;
/// Describe the SQL query and return type information about its parameters
/// and results.
///
/// This is used by compile-time verification in the query macros to
/// power their type inference.
#[doc(hidden)]
fn describe<'e>(self, sql: SqlStr) -> BoxFuture<'e, Result<Describe<Self::Database>, Error>>
where
'c: 'e;
}
/// A type that may be executed against a database connection.
///
/// Implemented for the following:
///
/// * [`&str`](std::str)
/// * [`Query`](super::query::Query)
///
pub trait Execute<'q, DB: Database>: Send + Sized {
/// Gets the SQL that will be executed.
fn sql(self) -> SqlStr;
/// Gets the previously cached statement, if available.
fn statement(&self) -> Option<&DB::Statement>;
/// Returns the arguments to be bound against the query string.
///
/// Returning `Ok(None)` for `Arguments` indicates to use a "simple" query protocol and to not
/// prepare the query. Returning `Ok(Some(Default::default()))` is an empty arguments object that
/// will be prepared (and cached) before execution.
///
/// Returns `Err` if encoding any of the arguments failed.
fn take_arguments(&mut self) -> Result<Option<<DB as Database>::Arguments>, BoxDynError>;
/// Returns `true` if the statement should be cached.
fn persistent(&self) -> bool;
}
impl<DB: Database, T> Execute<'_, DB> for T
where
T: SqlSafeStr + Send,
{
#[inline]
fn sql(self) -> SqlStr {
self.into_sql_str()
}
#[inline]
fn statement(&self) -> Option<&DB::Statement> {
None
}
#[inline]
fn take_arguments(&mut self) -> Result<Option<<DB as Database>::Arguments>, BoxDynError> {
Ok(None)
}
#[inline]
fn persistent(&self) -> bool {
true
}
}
impl<DB: Database, T> Execute<'_, DB> for (T, Option<<DB as Database>::Arguments>)
where
T: SqlSafeStr + Send,
{
#[inline]
fn sql(self) -> SqlStr {
self.0.into_sql_str()
}
#[inline]
fn statement(&self) -> Option<&DB::Statement> {
None
}
#[inline]
fn take_arguments(&mut self) -> Result<Option<<DB as Database>::Arguments>, BoxDynError> {
Ok(self.1.take())
}
#[inline]
fn persistent(&self) -> bool {
true
}
}