[]byte skips encoding/decoding

refs #104

conn.go

@@ -861,6 +861,8 @@ func (c *Conn) sendPreparedQuery(ps *PreparedStatement, arguments ...interface{}
 			err = arg.Encode(wbuf, oid)
 		case string:
 			err = encodeText(wbuf, arguments[i])
+		case []byte:
+			err = encodeBytea(wbuf, arguments[i])
 		default:
 			if v := reflect.ValueOf(arguments[i]); v.Kind() == reflect.Ptr {
 				if v.IsNil() {

doc.go

@@ -181,6 +181,14 @@ Conn.PgTypes.
 See example_custom_type_test.go for an example of a custom type for the
 PostgreSQL point type.
 
+[]byte Mapping
+
+[]byte passed as arguments to Query, QueryRow, and Exec are passed unmodified
+to PostgreSQL. In like manner, a *[]byte passed to Scan will be filled with
+the raw bytes returned by PostgreSQL. This can be especially useful for reading
+varchar, text, json, and jsonb values directly into a []byte and avoiding the
+type conversion from string.
+
 TLS
 
 The pgx ConnConfig struct has a TLSConfig field. If this field is

query.go

@@ -11,10 +11,9 @@ import (
 // Row is a convenience wrapper over Rows that is returned by QueryRow.
 type Row Rows
 
-// Scan reads the values from the row into dest values positionally. dest can
-// include pointers to core types and the Scanner interface. If no rows were
-// found it returns ErrNoRows. If multiple rows are returned it ignores all but
-// the first.
+// Scan works the same as (*Rows Scan) with the following exceptions. If no
+// rows were found it returns ErrNoRows. If multiple rows are returned it
+// ignores all but the first.
 func (r *Row) Scan(dest ...interface{}) (err error) {
 	rows := (*Rows)(r)
 
@@ -216,7 +215,9 @@ func (rows *Rows) nextColumn() (*ValueReader, bool) {
 }
 
 // Scan reads the values from the current row into dest values positionally.
-// dest can include pointers to core types and the Scanner interface.
+// dest can include pointers to core types, values implementing the Scanner
+// interface, and []byte. []byte will skip the decoding process and directly
+// copy the raw bytes received from PostgreSQL.
 func (rows *Rows) Scan(dest ...interface{}) (err error) {
 	if len(rows.fields) != len(dest) {
 		err = fmt.Errorf("Scan received wrong number of arguments, got %d but expected %d", len(dest), len(rows.fields))

query_test.go

@@ -431,6 +431,7 @@ func TestQueryRowCoreByteSlice(t *testing.T) {
 	}{
 		{"select $1::text", "Jack", []byte("Jack")},
 		{"select $1::text", []byte("Jack"), []byte("Jack")},
+		{"select $1::int4", int32(239023409), []byte{14, 63, 53, 49}},
 		{"select $1::varchar", []byte("Jack"), []byte("Jack")},
 		{"select $1::bytea", []byte{0, 15, 255, 17}, []byte{0, 15, 255, 17}},
 	}
@@ -451,6 +452,30 @@ func TestQueryRowCoreByteSlice(t *testing.T) {
 	}
 }
 
+func TestQueryRowByteSliceArgument(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	sql := "select $1::int4"
+	queryArg := []byte{14, 63, 53, 49}
+	expected := int32(239023409)
+
+	var actual int32
+
+	err := conn.QueryRow(sql, queryArg).Scan(&actual)
+	if err != nil {
+		t.Errorf("Unexpected failure: %v (sql -> %v)", err, sql)
+	}
+
+	if expected != actual {
+		t.Errorf("Expected %v, got %v (sql -> %v)", expected, actual, sql)
+	}
+
+	ensureConnValid(t, conn)
+}
+
 func TestQueryRowUnknownType(t *testing.T) {
 	t.Parallel()
 

stdlib/sql_test.go

@@ -436,6 +436,80 @@ func TestConnQueryRowUnknownType(t *testing.T) {
 	ensureConnValid(t, db)
 }
 
+func TestConnQueryJSONIntoByteSlice(t *testing.T) {
+	db := openDB(t)
+	defer closeDB(t, db)
+
+	_, err := db.Exec(`
+		create temporary table docs(
+			body json not null
+		);
+
+		insert into docs(body) values('{"foo":"bar"}');
+`)
+	if err != nil {
+		t.Fatalf("db.Exec unexpectedly failed: %v", err)
+	}
+
+	sql := `select * from docs`
+	expected := []byte(`{"foo":"bar"}`)
+	var actual []byte
+
+	err = db.QueryRow(sql).Scan(&actual)
+	if err != nil {
+		t.Errorf("Unexpected failure: %v (sql -> %v)", err, sql)
+	}
+
+	if bytes.Compare(actual, expected) != 0 {
+		t.Errorf(`Expected "%v", got "%v" (sql -> %v)`, string(expected), string(actual), sql)
+	}
+
+	_, err = db.Exec(`drop table docs`)
+	if err != nil {
+		t.Fatalf("db.Exec unexpectedly failed: %v", err)
+	}
+
+	ensureConnValid(t, db)
+}
+
+func TestConnExecInsertByteSliceIntoJSON(t *testing.T) {
+	db := openDB(t)
+	defer closeDB(t, db)
+
+	_, err := db.Exec(`
+		create temporary table docs(
+			body json not null
+		);
+`)
+	if err != nil {
+		t.Fatalf("db.Exec unexpectedly failed: %v", err)
+	}
+
+	expected := []byte(`{"foo":"bar"}`)
+
+	_, err = db.Exec(`insert into docs(body) values($1)`, expected)
+	if err != nil {
+		t.Fatalf("db.Exec unexpectedly failed: %v", err)
+	}
+
+	var actual []byte
+	err = db.QueryRow(`select body from docs`).Scan(&actual)
+	if err != nil {
+		t.Fatalf("db.QueryRow unexpectedly failed: %v", err)
+	}
+
+	if bytes.Compare(actual, expected) != 0 {
+		t.Errorf(`Expected "%v", got "%v"`, string(expected), string(actual))
+	}
+
+	_, err = db.Exec(`drop table docs`)
+	if err != nil {
+		t.Fatalf("db.Exec unexpectedly failed: %v", err)
+	}
+
+	ensureConnValid(t, db)
+}
+
 func TestTransactionLifeCycle(t *testing.T) {
 	db := openDB(t)
 	defer closeDB(t, db)