[postgres] Add support for ON CONFLICT clause

postgres/clause_test.go

@@ -0,0 +1,34 @@
+package postgres
+
+import "testing"
+
+func TestOnConflict(t *testing.T) {
+
+	assertClauseSerialize(t, &onConflictClause{}, "")
+
+	onConflict := &onConflictClause{}
+	onConflict.DO_NOTHING()
+	assertClauseSerialize(t, onConflict, "")
+
+	onConflict = &onConflictClause{indexExpressions: ColumnList{table1ColBool}}
+	onConflict.DO_NOTHING()
+	assertClauseSerialize(t, onConflict, `
+ON CONFLICT (col_bool) DO NOTHING`)
+
+	onConflict = &onConflictClause{indexExpressions: ColumnList{table1ColBool}}
+	onConflict.ON_CONSTRAINT("table_pkey").DO_NOTHING()
+	assertClauseSerialize(t, onConflict, `
+ON CONFLICT (col_bool) ON CONSTRAINT table_pkey DO NOTHING`)
+
+	onConflict = &onConflictClause{indexExpressions: ColumnList{table1ColBool, table2ColFloat}}
+	onConflict.WHERE(table2ColFloat.ADD(table1ColInt).GT(table1ColFloat)).DO_UPDATE(
+		SET(table1ColBool, Bool(true)).
+			SET(table1ColInt, Int(1)).
+			WHERE(table2ColFloat.GT(Float(11.1))),
+	)
+	assertClauseSerialize(t, onConflict, `
+ON CONFLICT (col_bool, col_float) WHERE (col_float + col_int) > col_float DO UPDATE
+       SET col_bool = $1,
+           col_int = $2
+       WHERE table2.col_float > $3`)
+}