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use futures_core::Stream;
use futures_util::{future, TryStreamExt};
use crate::arguments::{Arguments, ImmutableArguments};
use crate::{
arguments::IntoArguments, database::Database, encode::Encode, executor::Executor, row::FromRow,
types::HasSqlType,
};
/// SQL query with bind parameters, which maps rows to an explicit output type.
///
/// Returned by [query_as] and [query!] *et al*.
///
/// The methods on this struct should be passed a reference to [crate::Pool] or one of
/// the connection types.
pub struct QueryAs<'q, DB, R, P = <DB as Database>::Arguments>
where
DB: Database,
{
query: &'q str,
args: P,
map_row: fn(DB::Row) -> crate::Result<R>,
}
/// The result of [query!] for SQL queries that does not return output.
impl<DB, P> QueryAs<'_, DB, (), P>
where
DB: Database,
P: IntoArguments<DB> + Send,
{
/// Execute the query for its side-effects.
///
/// Returns the number of rows affected, or 0 if not applicable.
pub async fn execute<E>(self, executor: &mut E) -> crate::Result<u64>
where
E: Executor<Database = DB>,
{
executor
.execute(self.query, self.args.into_arguments())
.await
}
}
impl<'q, DB, R, P> QueryAs<'q, DB, R, P>
where
DB: Database,
P: IntoArguments<DB> + Send,
R: Send + 'q,
{
/// Execute the query, returning the rows as a futures `Stream`.
///
/// Use [fetch_all] if you want a `Vec` instead.
pub fn fetch<'e, E>(self, executor: &'e mut E) -> impl Stream<Item = crate::Result<R>> + 'e
where
E: Executor<Database = DB>,
'q: 'e,
{
let Self {
query,
args,
map_row,
..
} = self;
executor
.fetch(query, args.into_arguments())
.and_then(move |row| future::ready(map_row(row)))
}
/// Execute the query and get all rows from the result as a `Vec`.
pub async fn fetch_all<E>(self, executor: &mut E) -> crate::Result<Vec<R>>
where
E: Executor<Database = DB>,
{
self.fetch(executor).try_collect().await
}
/// Execute a query which should return either 0 or 1 rows.
///
/// Returns [crate::Error::FoundMoreThanOne] if more than 1 row is returned.
/// Use `.fetch().try_next()` if you just want one row.
pub async fn fetch_optional<E>(self, executor: &mut E) -> crate::Result<Option<R>>
where
E: Executor<Database = DB>,
{
executor
.fetch_optional(self.query, self.args.into_arguments())
.await?
.map(self.map_row)
.transpose()
}
/// Execute a query which should return exactly 1 row.
///
/// * Returns [crate::Error::NotFound] if 0 rows are returned.
/// * Returns [crate::Error::FoundMoreThanOne] if more than one row is returned.
pub async fn fetch_one<E>(self, executor: &mut E) -> crate::Result<R>
where
E: Executor<Database = DB>,
{
(self.map_row)(
executor
.fetch_one(self.query, self.args.into_arguments())
.await?,
)
}
}
impl<'q, DB, R> QueryAs<'q, DB, R>
where
DB: Database,
DB::Arguments: Arguments<Database = DB>,
{
/// Bind a value for use with this SQL query.
///
/// # Logic Safety
///
/// This function should be used with care, as SQLx cannot validate
/// that the value is of the right type nor can it validate that you have
/// passed the correct number of parameters.
pub fn bind<T>(mut self, value: T) -> Self
where
DB: HasSqlType<T>,
T: Encode<DB>,
{
self.args.add(value);
self
}
// used by query!() and friends
#[doc(hidden)]
pub fn bind_all(self, values: DB::Arguments) -> QueryAs<'q, DB, R, ImmutableArguments<DB>> {
QueryAs {
query: self.query,
args: ImmutableArguments(values),
map_row: self.map_row,
}
}
}
/// Construct a dynamic SQL query with an explicit output type implementing [FromRow].
#[inline]
pub fn query_as<DB, T>(query: &str) -> QueryAs<DB, T>
where
DB: Database,
T: FromRow<DB::Row>,
{
QueryAs {
query,
args: Default::default(),
map_row: |row| Ok(T::from_row(row)),
}
}
#[doc(hidden)]
pub fn query_as_mapped<DB, T>(
query: &str,
map_row: fn(DB::Row) -> crate::Result<T>,
) -> QueryAs<DB, T>
where
DB: Database,
{
QueryAs {
query,
args: Default::default(),
map_row,
}
}