diff --git a/src/backend/query_builder.rs b/src/backend/query_builder.rs index 7bf29b55..785971b4 100644 --- a/src/backend/query_builder.rs +++ b/src/backend/query_builder.rs @@ -387,9 +387,24 @@ pub trait QueryBuilder: SimpleExpr::Constant(val) => { self.prepare_constant(val, sql); } + SimpleExpr::IfElse(val) => { + self.prepare_if_else_statement(val, sql); + } } } + fn prepare_if_else_statement(&self, val: &Box, sql: &mut dyn SqlWriter) { + write!(sql, "IF ").unwrap(); + self.prepare_simple_expr(&val.when, sql); + write!(sql, " THEN\n").unwrap(); + self.prepare_simple_expr(&val.then, sql); + if let Some(otherwise) = &val.otherwise { + write!(sql, "\nELSE\n").unwrap(); + self.prepare_simple_expr(otherwise, sql); + }; + write!(sql, "\nEND IF").unwrap(); + } + /// Translate [`CaseStatement`] into SQL statement. fn prepare_case_statement(&self, stmts: &CaseStatement, sql: &mut dyn SqlWriter) { write!(sql, "(CASE").unwrap(); diff --git a/src/expr.rs b/src/expr.rs index 06cf08ed..8a9f1072 100644 --- a/src/expr.rs +++ b/src/expr.rs @@ -4,7 +4,7 @@ //! //! [`SimpleExpr`] is the expression common among select fields, where clauses and many other places. -use crate::{func::*, query::*, types::*, value::*}; +use crate::{func::*, query::*, types::*, value::*, if_else::*}; /// Helper to build a [`SimpleExpr`]. #[derive(Debug, Clone)] @@ -35,6 +35,7 @@ pub enum SimpleExpr { AsEnum(DynIden, Box), Case(Box), Constant(Value), + IfElse(Box), } /// "Operator" methods for building complex expressions. diff --git a/src/if_else.rs b/src/if_else.rs new file mode 100644 index 00000000..b6f9779d --- /dev/null +++ b/src/if_else.rs @@ -0,0 +1,35 @@ +use crate::{QueryBuilder, SimpleExpr}; + +#[derive(Debug, Clone, PartialEq)] +pub struct IfElseStatement { + pub when: SimpleExpr, + pub then: SimpleExpr, + pub otherwise: Option +} + +impl IfElseStatement { + + pub fn new(when: SimpleExpr, then: SimpleExpr, otherwise: Option) -> Self { + Self { + when, + then, + otherwise + } + } + + pub fn to_string(&self, query_builder: T) -> String { + let mut sql = String::with_capacity(256); + query_builder.prepare_if_else_statement(&Box::new(self.clone()), &mut sql); + sql + } + +} +pub trait IfElseStatementBuilder { + /// Build corresponding SQL statement for certain database backend and return SQL string + fn build(&self, query_builder: T) -> String; + + /// Build corresponding SQL statement for certain database backend and return SQL string + fn to_string(&self, query_builder: T) -> String { + self.build(query_builder) + } +} diff --git a/src/lib.rs b/src/lib.rs index 15e1a189..e4e8c7cf 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -826,6 +826,7 @@ pub mod table; pub mod token; pub mod types; pub mod value; +pub mod if_else; #[doc(hidden)] #[cfg(feature = "tests-cfg")] @@ -843,6 +844,7 @@ pub use table::*; pub use token::*; pub use types::*; pub use value::*; +pub use if_else::*; #[cfg(feature = "derive")] pub use sea_query_derive::{enum_def, Iden, IdenStatic}; diff --git a/tests/mysql/if_else.rs b/tests/mysql/if_else.rs new file mode 100644 index 00000000..15c9de4b --- /dev/null +++ b/tests/mysql/if_else.rs @@ -0,0 +1,42 @@ +use super::*; +use pretty_assertions::assert_eq; + +#[test] +fn if_without_else() { + let query = Query::select().column(Asterisk).from(Glyph::Table).take(); + let then = SimpleExpr::SubQuery(None, Box::new(query.into_sub_query_statement())); + let if_statement = IfElseStatement::new( + Expr::col(Glyph::Id).eq(1), + then, + None + ); + assert_eq!( + if_statement.to_string(MysqlQueryBuilder), + [ + "IF `id` = 1 THEN", + "(SELECT * FROM `glyph`)", + "END IF" + ].join("\n") + ) +} + +#[test] +fn if_with_else() { + let query = Query::select().column(Asterisk).from(Glyph::Table).take(); + let then = SimpleExpr::SubQuery(None, Box::new(query.into_sub_query_statement())); + let if_statement = IfElseStatement::new( + Expr::col(Glyph::Id).eq(1), + then, + Some(Expr::val("23").into()) + ); + assert_eq!( + if_statement.to_string(MysqlQueryBuilder), + [ + "IF `id` = 1 THEN", + "(SELECT * FROM `glyph`)", + "ELSE", + "'23'", + "END IF" + ].join("\n") + ) +} diff --git a/tests/mysql/mod.rs b/tests/mysql/mod.rs index d717774f..3facb1e5 100644 --- a/tests/mysql/mod.rs +++ b/tests/mysql/mod.rs @@ -4,6 +4,7 @@ mod foreign_key; mod index; mod query; mod table; +mod if_else; #[path = "../common.rs"] mod common;