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use crate::{Condition, IntoCondition, SimpleExpr};
#[derive(Debug, Clone, PartialEq)]
pub(crate) struct CaseStatementCondition {
pub(crate) condition: Condition,
pub(crate) result: SimpleExpr,
}
#[derive(Debug, Clone, Default, PartialEq)]
pub struct CaseStatement {
pub(crate) when: Vec<CaseStatementCondition>,
pub(crate) r#else: Option<SimpleExpr>,
}
impl CaseStatement {
/// Creates a new case statement expression
///
/// # Examples
///
/// ```
/// use sea_query::{*, tests_cfg::*};
///
/// let query = Query::select()
/// .expr_as(
/// CaseStatement::new()
/// .case(Expr::col((Glyph::Table, Glyph::Aspect)).is_in([2, 4]), true)
/// .finally(false),
/// "is_even"
/// )
/// .from(Glyph::Table)
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(PostgresQueryBuilder),
/// r#"SELECT (CASE WHEN ("glyph"."aspect" IN (2, 4)) THEN TRUE ELSE FALSE END) AS "is_even" FROM "glyph""#
/// );
/// ```
pub fn new() -> Self {
Self::default()
}
/// Adds new `CASE WHEN` to existing case statement.
///
/// # Examples
///
/// ```
/// use sea_query::{*, tests_cfg::*};
///
/// let query = Query::select()
/// .expr_as(
/// Expr::case(
/// Expr::col((Glyph::Table, Glyph::Aspect)).gt(0),
/// "positive"
/// )
/// .case(
/// Expr::col((Glyph::Table, Glyph::Aspect)).lt(0),
/// "negative"
/// )
/// .finally("zero"),
/// "polarity"
/// )
/// .from(Glyph::Table)
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(PostgresQueryBuilder),
/// r#"SELECT (CASE WHEN ("glyph"."aspect" > 0) THEN 'positive' WHEN ("glyph"."aspect" < 0) THEN 'negative' ELSE 'zero' END) AS "polarity" FROM "glyph""#
/// );
/// ```
pub fn case<C, T>(mut self, cond: C, then: T) -> Self
where
C: IntoCondition,
T: Into<SimpleExpr>,
{
self.when.push(CaseStatementCondition {
condition: cond.into_condition(),
result: then.into(),
});
self
}
/// Ends the case statement with the final `ELSE` result.
///
/// # Examples
///
/// ```
/// use sea_query::{*, tests_cfg::*};
///
/// let query = Query::select()
/// .expr_as(
/// Expr::case(
/// Cond::any()
/// .add(Expr::col((Character::Table, Character::FontSize)).gt(48))
/// .add(Expr::col((Character::Table, Character::SizeW)).gt(500)),
/// "large"
/// )
/// .case(
/// Cond::any()
/// .add(Expr::col((Character::Table, Character::FontSize)).between(24,48))
/// .add(Expr::col((Character::Table, Character::SizeW)).between(300,500)),
/// "medium"
/// )
/// .finally("small"),
/// "char_size")
/// .from(Character::Table)
/// .to_owned();
///
/// assert_eq!(
/// query.to_string(PostgresQueryBuilder),
/// [
/// r#"SELECT"#,
/// r#"(CASE WHEN ("character"."font_size" > 48 OR "character"."size_w" > 500) THEN 'large'"#,
/// r#"WHEN (("character"."font_size" BETWEEN 24 AND 48) OR ("character"."size_w" BETWEEN 300 AND 500)) THEN 'medium'"#,
/// r#"ELSE 'small' END) AS "char_size""#,
/// r#"FROM "character""#
/// ]
/// .join(" ")
/// );
/// ```
pub fn finally<E>(mut self, r#else: E) -> Self
where
E: Into<SimpleExpr>,
{
self.r#else = Some(r#else.into());
self
}
}
#[allow(clippy::from_over_into)]
impl Into<SimpleExpr> for CaseStatement {
fn into(self) -> SimpleExpr {
SimpleExpr::Case(Box::new(self))
}
}
#[cfg(test)]
mod test {
use crate::*;
#[test]
#[cfg(feature = "backend-postgres")]
fn test_where_case_eq() {
let case_statement: SimpleExpr = Expr::case(Expr::col("col").lt(5), Expr::col("othercol"))
.finally(Expr::col("finalcol"))
.into();
let result = Query::select()
.column(Asterisk)
.from("tbl")
.and_where(case_statement.eq(10))
.to_string(PostgresQueryBuilder);
assert_eq!(
result,
r#"SELECT * FROM "tbl" WHERE (CASE WHEN ("col" < 5) THEN "othercol" ELSE "finalcol" END) = 10"#
);
}
}