Add compatibility with database/sql custom types

Support database/sql.Scanner
Support database/sql/driver.Valuer

query_test.go

@@ -2,10 +2,13 @@ package pgx_test
 
 import (
 	"bytes"
+	"database/sql"
 	"github.com/jackc/pgx"
 	"strings"
 	"testing"
 	"time"
+
+	"github.com/shopspring/decimal"
 )
 
 func TestConnQueryScan(t *testing.T) {
@@ -904,3 +907,113 @@ func TestReadingNullByteArrays(t *testing.T) {
 		t.Errorf("Expected to read 2 rows, read: ", count)
 	}
 }
+
+// Use github.com/shopspring/decimal as real-world database/sql custom type
+// to test against.
+func TestConnQueryDatabaseSQLScanner(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	var num decimal.Decimal
+
+	err := conn.QueryRow("select '1234.567'::decimal").Scan(&num)
+	if err != nil {
+		t.Fatalf("Scan failed: %v", err)
+	}
+
+	expected, err := decimal.NewFromString("1234.567")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !num.Equals(expected) {
+		t.Errorf("Expected num to be %v, but it was %v", expected, num)
+	}
+
+	ensureConnValid(t, conn)
+}
+
+// Use github.com/shopspring/decimal as real-world database/sql custom type
+// to test against.
+func TestConnQueryDatabaseSQLDriverValuer(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	expected, err := decimal.NewFromString("1234.567")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var num decimal.Decimal
+
+	err = conn.QueryRow("select $1::decimal", expected).Scan(&num)
+	if err != nil {
+		t.Fatalf("Scan failed: %v", err)
+	}
+
+	if !num.Equals(expected) {
+		t.Errorf("Expected num to be %v, but it was %v", expected, num)
+	}
+
+	ensureConnValid(t, conn)
+}
+
+func TestConnQueryDatabaseSQLNullX(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	type row struct {
+		boolValid    sql.NullBool
+		boolNull     sql.NullBool
+		int64Valid   sql.NullInt64
+		int64Null    sql.NullInt64
+		float64Valid sql.NullFloat64
+		float64Null  sql.NullFloat64
+		stringValid  sql.NullString
+		stringNull   sql.NullString
+	}
+
+	expected := row{
+		boolValid:    sql.NullBool{Bool: true, Valid: true},
+		int64Valid:   sql.NullInt64{Int64: 123, Valid: true},
+		float64Valid: sql.NullFloat64{Float64: 3.14, Valid: true},
+		stringValid:  sql.NullString{String: "pgx", Valid: true},
+	}
+
+	var actual row
+
+	err := conn.QueryRow(
+		"select $1::bool, $2::bool, $3::int8, $4::int8, $5::float8, $6::float8, $7::text, $8::text",
+		expected.boolValid,
+		expected.boolNull,
+		expected.int64Valid,
+		expected.int64Null,
+		expected.float64Valid,
+		expected.float64Null,
+		expected.stringValid,
+		expected.stringNull,
+	).Scan(
+		&actual.boolValid,
+		&actual.boolNull,
+		&actual.int64Valid,
+		&actual.int64Null,
+		&actual.float64Valid,
+		&actual.float64Null,
+		&actual.stringValid,
+		&actual.stringNull,
+	)
+	if err != nil {
+		t.Fatalf("Scan failed: %v", err)
+	}
+
+	if expected != actual {
+		t.Errorf("Expected %v, but got %v", expected, actual)
+	}
+
+	ensureConnValid(t, conn)
+}