Add NullRawMessage type

Author: kyleconroy

json.go

@@ -0,0 +1,40 @@
+package pqtype
+
+import (
+	"database/sql/driver"
+	"encoding/json"
+	"fmt"
+)
+
+// NullRawMessage represents a json.RawMessage that may be null.
+// NullRawMessage implements the Scanner interface so
+// it can be used as a scan destination, similar to NullString.
+type NullRawMessage struct {
+	RawMessage json.RawMessage
+	Valid      bool // Valid is true if RawMessage is not NULL
+}
+
+// Scan implements the Scanner interface.
+func (n *NullRawMessage) Scan(src interface{}) error {
+	if src == nil {
+		n.Valid = false
+		return nil
+	}
+	switch src := src.(type) {
+	case []byte:
+		srcCopy := make([]byte, len(src))
+		copy(srcCopy, src)
+		n.RawMessage, n.Valid = srcCopy, true
+	default:
+		return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, []byte{})
+	}
+	return nil
+}
+
+// Value implements the driver Valuer interface.
+func (n NullRawMessage) Value() (driver.Value, error) {
+	if !n.Valid {
+		return nil, nil
+	}
+	return n.RawMessage, nil
+}

tests/json_test.go

@@ -0,0 +1,61 @@
+package tests
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/tabbed/pqtype"
+)
+
+func TestJSONRawMessage(t *testing.T) {
+	for _, payload := range []string{
+		`{}`,
+		`[]`,
+		`1`,
+		`1.2`,
+		`"a"`,
+		`true`,
+		`false`,
+		`{"foo": "bar"}`,
+	} {
+		payload = payload
+		t.Run(payload, func(t *testing.T) {
+			var n pqtype.NullRawMessage
+			if err := db.QueryRow(fmt.Sprintf(`SELECT '%s'::json`, payload)).Scan(&n); err != nil {
+				t.Fatal(err)
+			}
+			if diff := cmp.Diff(true, n.Valid); diff != "" {
+				t.Errorf("json valid mismatch (-want +got):\n%s", diff)
+			}
+			if diff := cmp.Diff(string(json.RawMessage(payload)), string(n.RawMessage)); diff != "" {
+				t.Errorf("json mismatch (-want +got):\n%s", diff)
+			}
+			if err := db.QueryRow(fmt.Sprintf(`SELECT '%s'::jsonb`, payload)).Scan(&n); err != nil {
+				t.Fatal(err)
+			}
+			if diff := cmp.Diff(true, n.Valid); diff != "" {
+				t.Errorf("jsonb valid mismatch (-want +got):\n%s", diff)
+			}
+			if diff := cmp.Diff(string(json.RawMessage(payload)), string(n.RawMessage)); diff != "" {
+				t.Errorf("jsonb mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+	t.Run("NULL", func(t *testing.T) {
+		var n pqtype.NullRawMessage
+		if err := db.QueryRow(`SELECT NULL::json`).Scan(&n); err != nil {
+			t.Fatal(err)
+		}
+		if diff := cmp.Diff(false, n.Valid); diff != "" {
+			t.Errorf("valid mismatch (-want +got):\n%s", diff)
+		}
+		if err := db.QueryRow(`SELECT NULL::jsonb`).Scan(&n); err != nil {
+			t.Fatal(err)
+		}
+		if diff := cmp.Diff(false, n.Valid); diff != "" {
+			t.Errorf("valid mismatch (-want +got):\n%s", diff)
+		}
+	})
+}