Add support for ON CONFLICT in InsertStmt

dialect.go

@@ -13,4 +13,7 @@ type Dialect interface {
 	EncodeBytes(b []byte) string
 
 	Placeholder(n int) string
+
+	OnConflict(constraint string) string
+	Proposed(column string) string
 }

dialect/mssql.go

@@ -34,3 +34,11 @@ func (d mssql) EncodeBytes(b []byte) string {
 func (d mssql) Placeholder(n int) string {
 	return fmt.Sprintf("@p%d", n+1)
 }
+
+func (d mssql) OnConflict(_ string) string {
+	return ""
+}
+
+func (d mssql) Proposed(_ string) string {
+	return ""
+}

dialect/mysql.go

@@ -64,3 +64,11 @@ func (d mysql) EncodeBytes(b []byte) string {
 func (d mysql) Placeholder(_ int) string {
 	return "?"
 }
+
+func (d mysql) OnConflict(_ string) string {
+	return "ON DUPLICATE KEY UPDATE"
+}
+
+func (d mysql) Proposed(column string) string {
+	return fmt.Sprintf("VALUES(%s)", d.QuoteIdent(column))
+}

dialect/postgresql.go

@@ -35,3 +35,11 @@ func (d postgreSQL) EncodeBytes(b []byte) string {
 func (d postgreSQL) Placeholder(n int) string {
 	return fmt.Sprintf("$%d", n+1)
 }
+
+func (d postgreSQL) OnConflict(constraint string) string {
+	return fmt.Sprintf("ON CONFLICT ON CONSTRAINT %s DO UPDATE SET", d.QuoteIdent(constraint))
+}
+
+func (d postgreSQL) Proposed(column string) string {
+	return fmt.Sprintf("EXCLUDED.%s", d.QuoteIdent(column))
+}

dialect/sqlite3.go

@@ -38,3 +38,11 @@ func (d sqlite3) EncodeBytes(b []byte) string {
 func (d sqlite3) Placeholder(_ int) string {
 	return "?"
 }
+
+func (d sqlite3) OnConflict(_ string) string {
+	return ""
+}
+
+func (d sqlite3) Proposed(_ string) string {
+	return ""
+}

insert.go

@@ -3,12 +3,19 @@ package dbr
 import (
 	"context"
 	"database/sql"
+	"fmt"
 	"reflect"
 	"strings"
 
 	"github.com/gocraft/dbr/v2/dialect"
 )
 
+// ConflictStmt is ` ON CONFLICT ...` part of InsertStmt
+type ConflictStmt struct {
+	constraint string
+	actions    map[string]interface{}
+}
+
 // InsertStmt builds `INSERT INTO ...`.
 type InsertStmt struct {
 	Runner
@@ -24,6 +31,16 @@ type InsertStmt struct {
 	ReturnColumn []string
 	RecordID     *int64
 	comments     Comments
+
+	Conflict *ConflictStmt
+}
+
+// Proposed is reference to proposed value in on conflict clause
+func Proposed(column string) Builder {
+	return BuildFunc(func(d Dialect, b Buffer) error {
+		_, err := b.WriteString(d.Proposed(column))
+		return err
+	})
 }
 
 type InsertBuilder = InsertStmt
@@ -90,6 +107,29 @@ func (b *InsertStmt) Build(d Dialect, buf Buffer) error {
 		buf.WriteValue(tuple...)
 	}
 
+	if b.Conflict != nil && len(b.Conflict.actions) > 0 {
+		keyword := d.OnConflict(b.Conflict.constraint)
+		if len(keyword) == 0 {
+			return fmt.Errorf("Dialect %s does not support OnConflict", d)
+		}
+		buf.WriteString(" ")
+		buf.WriteString(keyword)
+		buf.WriteString(" ")
+		needComma := false
+		for _, column := range b.Column {
+			if v, ok := b.Conflict.actions[column]; ok {
+				if needComma {
+					buf.WriteString(",")
+				}
+				buf.WriteString(d.QuoteIdent(column))
+				buf.WriteString("=")
+				buf.WriteString(placeholder)
+				buf.WriteValue(v)
+				needComma = true
+			}
+		}
+	}
+
 	if d != dialect.MSSQL && len(b.ReturnColumn) > 0 {
 		buf.WriteString(" RETURNING ")
 		for i, col := range b.ReturnColumn {
@@ -262,3 +302,20 @@ func (b *InsertStmt) LoadContext(ctx context.Context, value interface{}) error {
 func (b *InsertStmt) Load(value interface{}) error {
 	return b.LoadContext(context.Background(), value)
 }
+
+// OnConflictMap allows to add actions for constraint violation, e.g UPSERT
+func (b *InsertStmt) OnConflictMap(constraint string, actions map[string]interface{}) *InsertStmt {
+	b.Conflict = &ConflictStmt{constraint: constraint, actions: actions}
+	return b
+}
+
+// OnConflict creates an empty OnConflict section fo insert statement , e.g UPSERT
+func (b *InsertStmt) OnConflict(constraint string) *ConflictStmt {
+	return b.OnConflictMap(constraint, make(map[string]interface{})).Conflict
+}
+
+// Action adds action for column which will do if conflict happens
+func (b *ConflictStmt) Action(column string, action interface{}) *ConflictStmt {
+	b.actions[column] = action
+	return b
+}

insert_test.go

@@ -42,6 +42,28 @@ func TestPostgresReturning(t *testing.T) {
 	require.Equal(t, 0, sess.EventReceiver.(*testTraceReceiver).errored)
 }
 
+func TestOnConflict(t *testing.T) {
+	for _, sess := range testSession {
+		if sess.Dialect.OnConflict("") == "" {
+			// dialect does not support OnConflict
+			continue
+		}
+		t.Run(testSessionName(sess), func(t *testing.T) {
+			reset(t, sess)
+			for i := 0; i < 2; i++ {
+				b := sess.InsertInto("dbr_people").Columns("id", "name", "email").Values(1, "test", "[email protected]")
+				b.OnConflict("dbr_people_pkey").Action("email", Expr("CONCAT(?, 2)", Proposed("email")))
+				_, err := b.Exec()
+				require.NoError(t, err)
+			}
+			var value string
+			_, err := sess.SelectBySql("SELECT email FROM dbr_people WHERE id=?", "1").Load(&value)
+			require.NoError(t, err)
+			require.Equal(t, "[email protected]", value)
+		})
+	}
+}
+
 func BenchmarkInsertValuesSQL(b *testing.B) {
 	buf := NewBuffer()
 	for i := 0; i < b.N; i++ {