use super::{Alias, AliasSource};
use crate::backend::Backend;
use crate::dsl;
use crate::expression::{
is_aggregate, AppearsOnTable, AsExpression, Expression, SelectableExpression, ValidGrouping,
};
use crate::expression_methods::{EqAll, ExpressionMethods};
use crate::query_builder::{AstPass, FromClause, QueryFragment, QueryId, SelectStatement};
use crate::query_source::{AppearsInFromClause, Column, Once, QuerySource};
use crate::result::QueryResult;
use crate::sql_types;
use std::marker::PhantomData;
#[derive(Debug, Clone, Copy)]
pub struct AliasedField<S, F> {
pub(super) _alias_source: PhantomData<S>,
pub(super) _field: F,
}
impl<S, C> QueryId for AliasedField<S, C>
where
S: AliasSource + 'static,
S::Target: 'static,
C: Column<Table = S::Target> + 'static + QueryId,
{
type QueryId = Self;
const HAS_STATIC_QUERY_ID: bool = <C as QueryId>::HAS_STATIC_QUERY_ID;
}
impl<QS, S, C> AppearsOnTable<QS> for AliasedField<S, C>
where
S: AliasSource,
QS: AppearsInFromClause<Alias<S>, Count = Once>,
C: Column<Table = S::Target>,
{
}
impl<S, C, DB> QueryFragment<DB> for AliasedField<S, C>
where
S: AliasSource,
DB: Backend,
C: Column<Table = S::Target>,
{
fn walk_ast<'b>(&'b self, mut pass: AstPass<'_, 'b, DB>) -> QueryResult<()> {
pass.push_identifier(S::NAME)?;
pass.push_sql(".");
pass.push_identifier(C::NAME)?;
Ok(())
}
}
impl<S, C> Expression for AliasedField<S, C>
where
S: AliasSource,
C: Column<Table = S::Target> + Expression,
{
type SqlType = C::SqlType;
}
impl<S, C> SelectableExpression<Alias<S>> for AliasedField<S, C>
where
S: AliasSource,
C: Column<Table = S::Target>,
Self: AppearsOnTable<Alias<S>>,
{
}
impl<S, C> ValidGrouping<()> for AliasedField<S, C>
where
S: AliasSource,
C: Column<Table = S::Target>,
{
type IsAggregate = is_aggregate::No;
}
impl<S, C1, C2> ValidGrouping<AliasedField<S, C1>> for AliasedField<S, C2>
where
S: AliasSource,
C1: Column<Table = S::Target>,
C2: Column<Table = S::Target>,
C2: ValidGrouping<C1, IsAggregate = is_aggregate::Yes>,
{
type IsAggregate = is_aggregate::Yes;
}
impl<From, S, C> SelectableExpression<SelectStatement<FromClause<From>>> for AliasedField<S, C>
where
Self: SelectableExpression<From> + AppearsOnTable<SelectStatement<FromClause<From>>>,
From: QuerySource,
{
}
impl<S, C, T> EqAll<T> for AliasedField<S, C>
where
S: AliasSource,
C: Column<Table = S::Target>,
Self: ExpressionMethods,
<Self as Expression>::SqlType: sql_types::SqlType,
T: AsExpression<<Self as Expression>::SqlType>,
dsl::Eq<Self, T>: Expression<SqlType = sql_types::Bool>,
{
type Output = dsl::Eq<Self, T>;
fn eq_all(self, rhs: T) -> Self::Output {
self.eq(rhs)
}
}