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feat: add SelectExprTrait for ergonomic alias and window chaining #1040

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2e81db7
feat(query): add SelectExprTrait for ergonomic alias and window chaining
yuly3 Jan 11, 2026
9ec7a07
refactor: replace window/window_name API with unified over method
yuly3 Jan 11, 2026
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146 changes: 101 additions & 45 deletions src/query/select.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -201,6 +201,82 @@ where
}
}

impl From<WindowStatement> for WindowSelectType {
fn from(stmt: WindowStatement) -> Self {
Self::Query(stmt)
}
}

impl<T: IntoIden> From<T> for WindowSelectType {
fn from(iden: T) -> Self {
Self::Name(iden.into_iden())
}
}

/// Extension methods for building a [`SelectExpr`] from an expression.
///
/// This makes it ergonomic to attach select-specific modifiers (like `AS` and `OVER`) and pass the
/// result into [`SelectStatement::expr`].
///
/// # Examples
///
/// ```
/// use sea_query::{tests_cfg::*, *};
///
/// let query = Query::select()
/// .from(Char::Table)
/// .expr(
/// Expr::col(Char::Character)
/// .max()
/// .over(WindowStatement::partition_by(Char::FontSize))
/// .alias("C"),
/// )
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(MysqlQueryBuilder),
/// r#"SELECT MAX(`character`) OVER ( PARTITION BY `font_size` ) AS `C` FROM `character`"#
/// );
/// ```
pub trait SelectExprTrait: Sized {
fn alias<A>(self, alias: A) -> SelectExpr
where
A: IntoIden;

fn over(self, over_expr: impl Into<WindowSelectType>) -> SelectExpr;
}

impl SelectExprTrait for SelectExpr {
fn alias<A>(mut self, alias: A) -> SelectExpr
where
A: IntoIden,
{
self.alias = Some(alias.into_iden());
self
}

fn over(mut self, over_expr: impl Into<WindowSelectType>) -> SelectExpr {
self.window = Some(over_expr.into());
self
}
}

impl<T> SelectExprTrait for T
where
T: Into<Expr>,
{
fn alias<A>(self, alias: A) -> SelectExpr
where
A: IntoIden,
{
SelectExpr::from(self).alias(alias)
}

fn over(self, over_expr: impl Into<WindowSelectType>) -> SelectExpr {
SelectExpr::from(self).over(over_expr)
}
}

impl SelectStatement {
/// Construct a new [`SelectStatement`]
pub fn new() -> Self {
Expand Down Expand Up @@ -678,11 +754,7 @@ impl SelectStatement {
T: Into<Expr>,
A: IntoIden,
{
self.expr(SelectExpr {
expr: expr.into(),
alias: Some(alias.into_iden()),
window: None,
});
self.expr(expr.alias(alias));
self
}

Expand All @@ -696,33 +768,29 @@ impl SelectStatement {
/// let query = Query::select()
/// .from(Char::Table)
/// .expr_window(
/// Expr::col(Char::Character),
/// Expr::col(Char::Character).max(),
/// WindowStatement::partition_by(Char::FontSize),
/// )
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(MysqlQueryBuilder),
/// r#"SELECT `character` OVER ( PARTITION BY `font_size` ) FROM `character`"#
/// r#"SELECT MAX(`character`) OVER ( PARTITION BY `font_size` ) FROM `character`"#
/// );
/// assert_eq!(
/// query.to_string(PostgresQueryBuilder),
/// r#"SELECT "character" OVER ( PARTITION BY "font_size" ) FROM "character""#
/// r#"SELECT MAX("character") OVER ( PARTITION BY "font_size" ) FROM "character""#
/// );
/// assert_eq!(
/// query.to_string(SqliteQueryBuilder),
/// r#"SELECT "character" OVER ( PARTITION BY "font_size" ) FROM "character""#
/// r#"SELECT MAX("character") OVER ( PARTITION BY "font_size" ) FROM "character""#
/// );
/// ```
pub fn expr_window<T>(&mut self, expr: T, window: WindowStatement) -> &mut Self
where
T: Into<Expr>,
{
self.expr(SelectExpr {
expr: expr.into(),
alias: None,
window: Some(WindowSelectType::Query(window)),
});
self.expr(expr.over(window));
self
}

Expand All @@ -736,35 +804,31 @@ impl SelectStatement {
/// let query = Query::select()
/// .from(Char::Table)
/// .expr_window_as(
/// Expr::col(Char::Character),
/// Expr::col(Char::Character).max(),
/// WindowStatement::partition_by(Char::FontSize),
/// "C",
/// )
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(MysqlQueryBuilder),
/// r#"SELECT `character` OVER ( PARTITION BY `font_size` ) AS `C` FROM `character`"#
/// r#"SELECT MAX(`character`) OVER ( PARTITION BY `font_size` ) AS `C` FROM `character`"#
/// );
/// assert_eq!(
/// query.to_string(PostgresQueryBuilder),
/// r#"SELECT "character" OVER ( PARTITION BY "font_size" ) AS "C" FROM "character""#
/// r#"SELECT MAX("character") OVER ( PARTITION BY "font_size" ) AS "C" FROM "character""#
/// );
/// assert_eq!(
/// query.to_string(SqliteQueryBuilder),
/// r#"SELECT "character" OVER ( PARTITION BY "font_size" ) AS "C" FROM "character""#
/// r#"SELECT MAX("character") OVER ( PARTITION BY "font_size" ) AS "C" FROM "character""#
/// );
/// ```
pub fn expr_window_as<T, A>(&mut self, expr: T, window: WindowStatement, alias: A) -> &mut Self
where
T: Into<Expr>,
A: IntoIden,
{
self.expr(SelectExpr {
expr: expr.into(),
alias: Some(alias.into_iden()),
window: Some(WindowSelectType::Query(window)),
});
self.expr(expr.over(window).alias(alias));
self
}

Expand All @@ -777,33 +841,29 @@ impl SelectStatement {
///
/// let query = Query::select()
/// .from(Char::Table)
/// .expr_window_name(Expr::col(Char::Character), "w")
/// .expr_window_name(Expr::col(Char::Character).max(), "w")
/// .window("w", WindowStatement::partition_by(Char::FontSize))
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(MysqlQueryBuilder),
/// r#"SELECT `character` OVER `w` FROM `character` WINDOW `w` AS (PARTITION BY `font_size`)"#
/// r#"SELECT MAX(`character`) OVER `w` FROM `character` WINDOW `w` AS (PARTITION BY `font_size`)"#
/// );
/// assert_eq!(
/// query.to_string(PostgresQueryBuilder),
/// r#"SELECT "character" OVER "w" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// r#"SELECT MAX("character") OVER "w" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// );
/// assert_eq!(
/// query.to_string(SqliteQueryBuilder),
/// r#"SELECT "character" OVER "w" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// r#"SELECT MAX("character") OVER "w" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// );
/// ```
pub fn expr_window_name<T, W>(&mut self, expr: T, window: W) -> &mut Self
where
T: Into<Expr>,
W: IntoIden,
{
self.expr(SelectExpr {
expr: expr.into(),
alias: None,
window: Some(WindowSelectType::Name(window.into_iden())),
});
self.expr(expr.over(window));
self
}

Expand All @@ -816,21 +876,21 @@ impl SelectStatement {
///
/// let query = Query::select()
/// .from(Char::Table)
/// .expr_window_name_as(Expr::col(Char::Character), "w", "C")
/// .expr_window_name_as(Expr::col(Char::Character).max(), "w", "C")
/// .window("w", WindowStatement::partition_by(Char::FontSize))
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(MysqlQueryBuilder),
/// r#"SELECT `character` OVER `w` AS `C` FROM `character` WINDOW `w` AS (PARTITION BY `font_size`)"#
/// r#"SELECT MAX(`character`) OVER `w` AS `C` FROM `character` WINDOW `w` AS (PARTITION BY `font_size`)"#
/// );
/// assert_eq!(
/// query.to_string(PostgresQueryBuilder),
/// r#"SELECT "character" OVER "w" AS "C" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// r#"SELECT MAX("character") OVER "w" AS "C" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// );
/// assert_eq!(
/// query.to_string(SqliteQueryBuilder),
/// r#"SELECT "character" OVER "w" AS "C" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// r#"SELECT MAX("character") OVER "w" AS "C" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// );
/// ```
pub fn expr_window_name_as<T, W, A>(&mut self, expr: T, window: W, alias: A) -> &mut Self
Expand All @@ -839,11 +899,7 @@ impl SelectStatement {
A: IntoIden,
W: IntoIden,
{
self.expr(SelectExpr {
expr: expr.into(),
alias: Some(alias.into_iden()),
window: Some(WindowSelectType::Name(window.into_iden())),
});
self.expr(expr.over(window).alias(alias));
self
}

Expand Down Expand Up @@ -2549,21 +2605,21 @@ impl SelectStatement {
///
/// let query = Query::select()
/// .from(Char::Table)
/// .expr_window_name_as(Expr::col(Char::Character), "w", "C")
/// .expr_window_name_as(Expr::col(Char::Character).max(), "w", "C")
/// .window("w", WindowStatement::partition_by(Char::FontSize))
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(MysqlQueryBuilder),
/// r#"SELECT `character` OVER `w` AS `C` FROM `character` WINDOW `w` AS (PARTITION BY `font_size`)"#
/// r#"SELECT MAX(`character`) OVER `w` AS `C` FROM `character` WINDOW `w` AS (PARTITION BY `font_size`)"#
/// );
/// assert_eq!(
/// query.to_string(PostgresQueryBuilder),
/// r#"SELECT "character" OVER "w" AS "C" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// r#"SELECT MAX("character") OVER "w" AS "C" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// );
/// assert_eq!(
/// query.to_string(SqliteQueryBuilder),
/// r#"SELECT "character" OVER "w" AS "C" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// r#"SELECT MAX("character") OVER "w" AS "C" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
/// );
/// ```
pub fn window<A>(&mut self, name: A, window: WindowStatement) -> &mut Self
Expand Down
37 changes: 37 additions & 0 deletions tests/mysql/query.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -447,6 +447,15 @@ fn select_32() {
.to_string(MysqlQueryBuilder),
"SELECT `character` AS `C` FROM `character`"
);

// Same SQL as `expr_as`, but expressed via `SelectExprTrait`.
assert_eq!(
Query::select()
.expr(Expr::col(Char::Character).alias("C"))
.from(Char::Table)
.to_string(MysqlQueryBuilder),
"SELECT `character` AS `C` FROM `character`"
);
}

#[test]
Expand Down Expand Up @@ -1042,6 +1051,34 @@ fn select_61() {
);
}

#[test]
fn select_62() {
assert_eq!(
Query::select()
.from(Char::Table)
.expr(
Expr::col(Char::Character)
.max()
.over(WindowStatement::partition_by(Char::FontSize))
.alias("C"),
)
.to_string(MysqlQueryBuilder),
r#"SELECT MAX(`character`) OVER ( PARTITION BY `font_size` ) AS `C` FROM `character`"#
);
}

#[test]
fn select_63() {
assert_eq!(
Query::select()
.from(Char::Table)
.expr(Expr::col(Char::Character).max().over("w"))
.window("w", WindowStatement::partition_by(Char::FontSize))
.to_string(MysqlQueryBuilder),
r#"SELECT MAX(`character`) OVER `w` FROM `character` WINDOW `w` AS (PARTITION BY `font_size`)"#
);
}

#[test]
fn md5_fn() {
assert_eq!(
Expand Down
37 changes: 37 additions & 0 deletions tests/postgres/query.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -499,6 +499,15 @@ fn select_32() {
query.audit_unwrap().selected_tables(),
[Char::Table.into_iden()]
);

// Same SQL as `expr_as`, but expressed via `SelectExprTrait`.
assert_eq!(
Query::select()
.expr(Expr::col(Char::Character).alias("C"))
.from(Char::Table)
.to_string(PostgresQueryBuilder),
r#"SELECT "character" AS "C" FROM "character""#
);
}

#[test]
Expand Down Expand Up @@ -1262,6 +1271,34 @@ fn select_64() {
assert_eq!(query.audit_unwrap().selected_tables(), []);
}

#[test]
fn select_65() {
assert_eq!(
Query::select()
.from(Char::Table)
.expr(
Expr::col(Char::Character)
.max()
.over(WindowStatement::partition_by(Char::FontSize))
.alias("C"),
)
.to_string(PostgresQueryBuilder),
r#"SELECT MAX("character") OVER ( PARTITION BY "font_size" ) AS "C" FROM "character""#
);
}

#[test]
fn select_66() {
assert_eq!(
Query::select()
.from(Char::Table)
.expr(Expr::col(Char::Character).max().over("w"))
.window("w", WindowStatement::partition_by(Char::FontSize))
.to_string(PostgresQueryBuilder),
r#"SELECT MAX("character") OVER "w" FROM "character" WINDOW "w" AS (PARTITION BY "font_size")"#
);
}

#[test]
#[allow(clippy::approx_constant)]
fn insert_2() {
Expand Down
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