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use modifier::{Modifier, Set}; use std::borrow::Cow; use super::{ util, Condition, Conditions, Limit, Offset, Order, Orders, Query, Selection, Selections, Statement }; pub struct Select<'a> { table: Cow<'static, str>, conditions: Conditions<'a>, selections: Selections, orders: Orders, limit: Option<Limit>, offset: Option<Offset>, } impl<'a> Select<'a> { pub fn new(table: Cow<'static, str>) -> Select<'a> { Select { table: table, conditions: vec![], selections: vec![], orders: vec![], limit: None, offset: None } } } impl<'a> Statement<'a> for Select<'a> { fn into_query(self) -> Query<'a> { let mut query = String::from("SELECT "); if !self.selections.is_empty() { query.push_str(&util::keyword_list(self.selections.iter().map(|a| &a.0))); } else { query.push('*'); } query.push_str(&format!(" FROM {}", self.table)); if !self.conditions.is_empty() { query.push_str(" WHERE "); query.push_str(&util::condition_list(&self.conditions, 1)); } if !self.orders.is_empty() { query.push_str(" ORDER BY "); query.push_str(&util::order_list(&self.orders)); } if let Some(limit) = self.limit { query.push_str(&format!(" LIMIT {}", limit)); } if let Some(offset) = self.offset { query.push_str(&format!(" OFFSET {}", offset)); } query.push(';'); let condition_predicates = self.conditions.into_iter().map(|a| a.1); let condition_values = condition_predicates.flat_map(|p| p.into_values_iter()); let values = condition_values.collect::<Vec<_>>(); Query(query, values) } } impl<'a> Set for Select<'a> { } impl<'a> Modifier<Select<'a>> for Condition<'a> { fn modify(self, select: &mut Select<'a>) { select.conditions.push(self); } } impl<'a> Modifier<Select<'a>> for Conditions<'a> { fn modify(mut self, select: &mut Select<'a>) { select.conditions.append(&mut self); } } impl<'a> Modifier<Select<'a>> for Selection { fn modify(self, select: &mut Select<'a>) { select.selections.push(self); } } impl<'a> Modifier<Select<'a>> for Selections { fn modify(mut self, select: &mut Select<'a>) { select.selections.append(&mut self); } } impl<'a> Modifier<Select<'a>> for Order { fn modify(self, select: &mut Select<'a>) { select.orders.push(self); } } impl<'a> Modifier<Select<'a>> for Orders { fn modify(mut self, select: &mut Select<'a>) { select.orders.append(&mut self); } } impl<'a> Modifier<Select<'a>> for Limit { fn modify(self, select: &mut Select<'a>) { select.limit = Some(self); } } impl<'a> Modifier<Select<'a>> for Offset { fn modify(self, select: &mut Select<'a>) { select.offset = Some(self); } } #[cfg(test)] mod tests { use ::{Condition, Limit, Offset, Predicate, Selection, Set, Statement}; use super::*; #[test] fn select() { let expected = "SELECT name FROM test_table WHERE id = $1 AND xyz < $2;"; let id = 1; { let select = Select::new("test_table".into()) .set(Selection("name".into())) .set(Condition("id".into(), Predicate::Equal(&id))) .set(Condition("xyz".into(), Predicate::Less(&id))); assert_eq!(select.into_query().0, expected); } } #[test] fn select_all() { let expected = "SELECT * FROM test_table WHERE id = $1 LIMIT 20 OFFSET 5;"; let id = 1; { let select = Select::new("test_table".into()) .set(Condition("id".into(), Predicate::Equal(&id))) .set(Limit(20)) .set(Offset(5)); assert_eq!(select.into_query().0, expected); } } }