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use core::marker::PhantomData;
use crate::arguments::Arguments;
use crate::database::Database;
use crate::encode::Encode;
use crate::executor::Execute;
use crate::types::Type;
/// Raw SQL query with bind parameters, mapped to a concrete type
/// using [`FromRow`](trait.FromRow.html). Returned
/// by [`query_as`](fn.query_as.html).
pub struct QueryAs<'q, DB, O>
where
DB: Database,
{
query: &'q str,
arguments: <DB as Database>::Arguments,
database: PhantomData<DB>,
output: PhantomData<O>,
}
impl<'q, DB, O> QueryAs<'q, DB, O>
where
DB: Database,
{
/// Bind a value for use with this SQL query.
#[inline]
pub fn bind<T>(mut self, value: T) -> Self
where
T: Type<DB>,
T: Encode<DB>,
{
self.arguments.add(value);
self
}
}
impl<'q, DB, O: Send> Execute<'q, DB> for QueryAs<'q, DB, O>
where
DB: Database,
{
#[inline]
fn into_parts(self) -> (&'q str, Option<<DB as Database>::Arguments>) {
(self.query, Some(self.arguments))
}
}
/// Construct a raw SQL query that is mapped to a concrete type
/// using [`FromRow`](crate::row::FromRow).
///
/// Returns [`QueryAs`].
pub fn query_as<DB, O>(sql: &str) -> QueryAs<DB, O>
where
DB: Database,
{
QueryAs {
query: sql,
arguments: Default::default(),
database: PhantomData,
output: PhantomData,
}
}
// We need database-specific QueryAs traits to work around:
// https://github.com/rust-lang/rust/issues/62529
// If for some reason we miss that issue being resolved in a _stable_ edition of
// rust, please open up a 100 issues and shout as loud as you can to remove
// this unseemly hack.
#[allow(unused_macros)]
macro_rules! make_query_as {
($name:ident, $db:ident, $row:ident) => {
pub trait $name<'q, O> {
fn fetch<'e, E>(
self,
executor: E,
) -> futures_core::stream::BoxStream<'e, crate::Result<O>>
where
E: 'e + Send + crate::executor::RefExecutor<'e, Database = $db>,
O: 'e + Send + Unpin + for<'c> crate::row::FromRow<'c, $row<'c>>,
'q: 'e;
fn fetch_all<'e, E>(
self,
executor: E,
) -> futures_core::future::BoxFuture<'e, crate::Result<Vec<O>>>
where
E: 'e + Send + crate::executor::RefExecutor<'e, Database = $db>,
O: 'e + Send + for<'c> crate::row::FromRow<'c, $row<'c>>,
'q: 'e;
fn fetch_one<'e, E>(
self,
executor: E,
) -> futures_core::future::BoxFuture<'e, crate::Result<O>>
where
E: 'e + Send + crate::executor::RefExecutor<'e, Database = $db>,
O: 'e + Send + for<'c> crate::row::FromRow<'c, $row<'c>>,
'q: 'e;
fn fetch_optional<'e, E>(
self,
executor: E,
) -> futures_core::future::BoxFuture<'e, crate::Result<Option<O>>>
where
E: 'e + Send + crate::executor::RefExecutor<'e, Database = $db>,
O: 'e + Send + for<'c> crate::row::FromRow<'c, $row<'c>>,
'q: 'e;
}
impl<'q, O> $name<'q, O> for crate::query_as::QueryAs<'q, $db, O> {
fn fetch<'e, E>(
self,
executor: E,
) -> futures_core::stream::BoxStream<'e, crate::Result<O>>
where
E: 'e + Send + crate::executor::RefExecutor<'e, Database = $db>,
O: 'e + Send + Unpin + for<'c> crate::row::FromRow<'c, $row<'c>>,
'q: 'e,
{
use crate::cursor::Cursor;
Box::pin(async_stream::try_stream! {
let mut cursor = executor.fetch_by_ref(self);
while let Some(row) = cursor.next().await? {
let obj = O::from_row(row)?;
yield obj;
}
})
}
fn fetch_optional<'e, E>(
self,
executor: E,
) -> futures_core::future::BoxFuture<'e, crate::Result<Option<O>>>
where
E: 'e + Send + crate::executor::RefExecutor<'e, Database = $db>,
O: 'e + Send + for<'c> crate::row::FromRow<'c, $row<'c>>,
'q: 'e,
{
use crate::cursor::Cursor;
Box::pin(async move {
let mut cursor = executor.fetch_by_ref(self);
let row = cursor.next().await?;
row.map(O::from_row).transpose()
})
}
fn fetch_one<'e, E>(
self,
executor: E,
) -> futures_core::future::BoxFuture<'e, crate::Result<O>>
where
E: 'e + Send + crate::executor::RefExecutor<'e, Database = $db>,
O: 'e + Send + for<'c> crate::row::FromRow<'c, $row<'c>>,
'q: 'e,
{
use futures_util::TryFutureExt;
Box::pin(self.fetch_optional(executor).and_then(|row| match row {
Some(row) => futures_util::future::ready(Ok(row)),
None => futures_util::future::ready(Err(crate::Error::RowNotFound)),
}))
}
fn fetch_all<'e, E>(
self,
executor: E,
) -> futures_core::future::BoxFuture<'e, crate::Result<Vec<O>>>
where
E: 'e + Send + crate::executor::RefExecutor<'e, Database = $db>,
O: 'e + Send + for<'c> crate::row::FromRow<'c, $row<'c>>,
'q: 'e,
{
use crate::cursor::Cursor;
Box::pin(async move {
let mut cursor = executor.fetch_by_ref(self);
let mut out = Vec::new();
while let Some(row) = cursor.next().await? {
let obj = O::from_row(row)?;
out.push(obj);
}
Ok(out)
})
}
}
};
}