From ef7114a8ceec41043c2006dc7f4032962269b770 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Mon, 31 Jan 2022 20:39:50 -0600
Subject: [PATCH] Add DecodeValue and DecodeDatabaseSQLValue for ArrayCodec

---
 pgtype/array_codec.go      | 27 +++++++++++++++------------
 pgtype/array_codec_test.go | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/pgtype/array_codec.go b/pgtype/array_codec.go
index 5d847fae..901ea5f7 100644
--- a/pgtype/array_codec.go
+++ b/pgtype/array_codec.go
@@ -332,26 +332,29 @@ func (spac *scanPlanArrayCodec) Scan(src []byte, dst interface{}) error {
 	}
 }
 
-func (c ArrayCodec) DecodeDatabaseSQLValue(ci *ConnInfo, oid uint32, format int16, src []byte) (driver.Value, error) {
+func (c *ArrayCodec) DecodeDatabaseSQLValue(ci *ConnInfo, oid uint32, format int16, src []byte) (driver.Value, error) {
 	if src == nil {
 		return nil, nil
 	}
 
-	// var n int64
-	// err := c.PlanScan(ci, oid, format, &n, true).Scan(ci, oid, format, src, &n)
-	// return n, err
-
-	return nil, fmt.Errorf("not implemented")
+	switch format {
+	case TextFormatCode:
+		return string(src), nil
+	case BinaryFormatCode:
+		buf := make([]byte, len(src))
+		copy(buf, src)
+		return buf, nil
+	default:
+		return nil, fmt.Errorf("unknown format code %d", format)
+	}
 }
 
-func (c ArrayCodec) DecodeValue(ci *ConnInfo, oid uint32, format int16, src []byte) (interface{}, error) {
+func (c *ArrayCodec) DecodeValue(ci *ConnInfo, oid uint32, format int16, src []byte) (interface{}, error) {
 	if src == nil {
 		return nil, nil
 	}
 
-	// var n int16
-	// err := c.PlanScan(ci, oid, format, &n, true).Scan(ci, oid, format, src, &n)
-	// return n, err
-
-	return nil, fmt.Errorf("not implemented")
+	var slice []interface{}
+	err := ci.PlanScan(oid, format, &slice).Scan(src, &slice)
+	return slice, err
 }
diff --git a/pgtype/array_codec_test.go b/pgtype/array_codec_test.go
index c358586e..0c31dcee 100644
--- a/pgtype/array_codec_test.go
+++ b/pgtype/array_codec_test.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestArrayCodec(t *testing.T) {
@@ -70,3 +71,40 @@ func TestArrayCodecAnySlice(t *testing.T) {
 		assert.Equalf(t, tt.expected, actual, "%d", i)
 	}
 }
+
+func TestArrayCodecDecodeValue(t *testing.T) {
+	conn := testutil.MustConnectPgx(t)
+	defer testutil.MustCloseContext(t, conn)
+
+	for _, tt := range []struct {
+		sql      string
+		expected interface{}
+	}{
+		{
+			sql:      `select '{}'::int4[]`,
+			expected: []interface{}{},
+		},
+		{
+			sql:      `select '{1,2}'::int8[]`,
+			expected: []interface{}{int64(1), int64(2)},
+		},
+		{
+			sql:      `select '{foo,bar}'::text[]`,
+			expected: []interface{}{"foo", "bar"},
+		},
+	} {
+		t.Run(tt.sql, func(t *testing.T) {
+			rows, err := conn.Query(context.Background(), tt.sql)
+			require.NoError(t, err)
+
+			for rows.Next() {
+				values, err := rows.Values()
+				require.NoError(t, err)
+				require.Len(t, values, 1)
+				require.Equal(t, tt.expected, values[0])
+			}
+
+			require.NoError(t, rows.Err())
+		})
+	}
+}