orm: supoprt DISTINCT keyword (#26163)

Author: fleximus

vlib/orm/orm.v

@@ -184,17 +184,18 @@ pub mut:
 // types - Types to select
 pub struct SelectConfig {
 pub mut:
-	table      Table
-	is_count   bool
-	has_where  bool
-	has_order  bool
-	order      string
-	order_type OrderType
-	has_limit  bool
-	primary    string = 'id' // should be set if primary is different than 'id' and 'has_limit' is false
-	has_offset bool
-	fields     []string
-	types      []int
+	table        Table
+	is_count     bool
+	has_where    bool
+	has_order    bool
+	order        string
+	order_type   OrderType
+	has_limit    bool
+	primary      string = 'id' // should be set if primary is different than 'id' and 'has_limit' is false
+	has_offset   bool
+	has_distinct bool
+	fields       []string
+	types        []int
 }
 
 // Interfaces gets called from the backend and can be implemented
@@ -349,6 +350,10 @@ pub fn orm_stmt_gen(sql_dialect SQLDialect, table Table, q string, kind StmtKind
 pub fn orm_select_gen(cfg SelectConfig, q string, num bool, qm string, start_pos int, where QueryData) string {
 	mut str := 'SELECT '
 
+	if cfg.has_distinct {
+		str += 'DISTINCT '
+	}
+
 	if cfg.is_count {
 		str += 'COUNT(*)'
 	} else {

vlib/orm/orm_fn_test.v

@@ -168,6 +168,35 @@ fn test_orm_select_gen_with_all() {
 	assert query == "SELECT 'id', 'test', 'abc' FROM 'test_table' WHERE 'abc' = ?0 AND 'test' > ?1 ORDER BY '' DESC LIMIT ?2 OFFSET ?3;"
 }
 
+fn test_orm_select_gen_with_distinct() {
+	query := orm.orm_select_gen(orm.SelectConfig{
+		table:        orm.Table{
+			name: 'test_table'
+		}
+		fields:       get_select_fields()
+		has_distinct: true
+	}, "'", true, '?', 0, orm.QueryData{})
+
+	assert query == "SELECT DISTINCT 'id', 'test', 'abc' FROM 'test_table';"
+}
+
+fn test_orm_select_gen_with_distinct_and_where() {
+	query := orm.orm_select_gen(orm.SelectConfig{
+		table:        orm.Table{
+			name: 'test_table'
+		}
+		fields:       get_select_fields()
+		has_distinct: true
+		has_where:    true
+	}, "'", true, '?', 0, orm.QueryData{
+		fields: ['abc']
+		kinds:  [.eq]
+		is_and: []
+	})
+
+	assert query == "SELECT DISTINCT 'id', 'test', 'abc' FROM 'test_table' WHERE 'abc' = ?0;"
+}
+
 fn test_orm_table_gen() {
 	table := orm.Table{
 		name: 'test_table'

vlib/orm/orm_null_test.v

@@ -314,3 +314,21 @@ fn test_inserting_passed_optionals() {
 	assert res3[1].name == none
 	assert res3[2].name or { '' } == 'www'
 }
+
+fn test_distinct_select() {
+	db := MockDB.new()
+
+	sql db {
+		create table Foo
+	}!
+
+	_ := sql db {
+		select distinct from Foo
+	}!
+	assert db.st.last == 'SELECT DISTINCT `id`, `a`, `b`, `c`, `d`, `e`, `f`, `g`, `h` FROM `foo`;'
+
+	_ := sql db {
+		select distinct from Foo where e > 5
+	}!
+	assert db.st.last == 'SELECT DISTINCT `id`, `a`, `b`, `c`, `d`, `e`, `f`, `g`, `h` FROM `foo` WHERE `e` > ?;'
+}

vlib/orm/orm_test.v

@@ -409,3 +409,17 @@ fn test_orm() {
 		drop table TestTime
 	}!
 }
+
+fn test_distinct() {
+	db := sqlite.connect(':memory:') or { panic(err) }
+
+	// Create table without unique constraints to allow true duplicates
+	db.exec('CREATE TABLE items (name TEXT, category TEXT)')!
+	db.exec("INSERT INTO items VALUES ('Apple', 'Fruit'), ('Apple', 'Fruit'), ('Banana', 'Fruit')")!
+
+	without_distinct := db.exec('SELECT name, category FROM items')!
+	assert without_distinct.len == 3
+
+	with_distinct := db.exec('SELECT DISTINCT name, category FROM items')!
+	assert with_distinct.len == 2
+}

vlib/v/ast/ast.v

@@ -2292,12 +2292,13 @@ pub:
 	is_insert    bool // for insert expressions
 	inserted_var string
 
-	has_where  bool
-	has_order  bool
-	has_limit  bool
-	has_offset bool
-	has_desc   bool
-	is_array   bool
+	has_where    bool
+	has_order    bool
+	has_limit    bool
+	has_offset   bool
+	has_desc     bool
+	has_distinct bool
+	is_array     bool
 	// is_generated indicates a statement is generated by ORM for complex queries with related tables.
 	is_generated bool
 	pos          token.Pos

vlib/v/fmt/fmt.v

@@ -3083,6 +3083,9 @@ pub fn (mut f Fmt) sql_expr(node ast.SqlExpr) {
 	} else {
 		f.write('\tselect ')
 	}
+	if node.has_distinct {
+		f.write('distinct ')
+	}
 	sym := f.table.sym(node.table_expr.typ)
 	mut table_name := sym.name
 	if !table_name.starts_with('C.') && !table_name.starts_with('JS.') {

vlib/v/gen/c/orm.v

@@ -977,6 +977,7 @@ fn (mut g Gen) write_orm_select(node ast.SqlExpr, connection_var_name string, re
 
 	g.writeln('.has_limit = ${node.has_limit},')
 	g.writeln('.has_offset = ${node.has_offset},')
+	g.writeln('.has_distinct = ${node.has_distinct},')
 
 	if primary_field.name != '' {
 		g.writeln('.primary = _S("${primary_field.name}"),')

vlib/v/parser/orm.v

@@ -28,6 +28,7 @@ fn (mut p Parser) sql_expr() ast.Expr {
 	// kind := if is_select { ast.SqlExprKind.select_ } else { ast.SqlExprKind.insert }
 	mut inserted_var := ''
 	mut is_count := false
+	mut has_distinct := false
 	if is_insert {
 		inserted_var = p.check_name()
 		p.scope.mark_var_as_used(inserted_var)
@@ -36,7 +37,14 @@ fn (mut p Parser) sql_expr() ast.Expr {
 			p.error('expecting `into`')
 		}
 	} else if is_select {
-		is_count = p.check_name() == 'count'
+		n := p.check_name()
+		if n == 'distinct' {
+			has_distinct = true
+			n2 := p.check_name()
+			is_count = n2 == 'count'
+		} else {
+			is_count = n == 'count'
+		}
 	}
 	mut typ := ast.void_type
 
@@ -128,6 +136,7 @@ fn (mut p Parser) sql_expr() ast.Expr {
 		has_order:    has_order
 		order_expr:   order_expr
 		has_desc:     has_desc
+		has_distinct: has_distinct
 		is_array:     if is_count { false } else { true }
 		is_generated: false
 		inserted_var: inserted_var