wkb scanner: support hex encoded data from go-pg

Author: paulmach

encoding/wkb/scanner.go

@@ -3,7 +3,9 @@ package wkb
 import (
 	"database/sql"
 	"database/sql/driver"
+	"encoding/hex"
 	"errors"
+	"fmt"
 
 	"github.com/paulmach/orb"
 )
@@ -93,6 +95,17 @@ func (s *GeometryScanner) Scan(d interface{}) error {
 		return nil
 	}
 
+	// go-pg will return ST_AsBinary(*) data as `\xhexencoded` which
+	// needs to be converted to true binary for further decoding.
+	// Code detects the \x prefix and then converts the rest from Hex to binary.
+	if len(data) > 2 && data[0] == byte('\\') && data[1] == byte('x') {
+		n, err := hex.Decode(data, data[2:])
+		if err != nil {
+			return fmt.Errorf("thought the data was hex, but it is not: %v", err)
+		}
+		data = data[:n]
+	}
+
 	switch g := s.g.(type) {
 	case nil:
 		m, err := Unmarshal(data)

encoding/wkb/scanner_test.go

@@ -49,6 +49,38 @@ func TestScanNil(t *testing.T) {
 	})
 }
 
+func TestScanHexData(t *testing.T) {
+	cases := []struct {
+		name     string
+		data     []byte
+		expected orb.Point
+	}{
+		{
+			name:     "point",
+			data:     []byte(`\x0101000000e0d57267266e4840b22ac24d46b50240`),
+			expected: orb.Point{48.860547, 2.338513},
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			p := orb.Point{}
+			s := Scanner(&p)
+
+			err := s.Scan(tc.data)
+			if err != nil {
+				t.Fatalf("scan error: %v", err)
+			}
+
+			if !p.Equal(tc.expected) {
+				t.Errorf("unequal data")
+				t.Log(p)
+				t.Log(tc.expected)
+			}
+		})
+	}
+}
+
 func TestScanPoint(t *testing.T) {
 	cases := []struct {
 		name     string