Firestore/encoding text

firestore/from_value.go

@@ -15,6 +15,7 @@
 package firestore
 
 import (
+	"encoding"
 	"errors"
 	"fmt"
 	"reflect"
@@ -101,6 +102,18 @@ func setReflectFromProtoValue(v reflect.Value, vproto *pb.Value, c *Client) erro
 		return nil
 	}
 
+	// Check if type implement encoding
+	if v.CanAddr() {
+		switch e := v.Addr().Interface().(type) {
+		case encoding.TextUnmarshaler:
+			x, ok := val.(*pb.Value_StringValue)
+			if !ok {
+				return typeErr()
+			}
+			return e.UnmarshalText([]byte(x.StringValue))
+		}
+	}
+
 	switch v.Kind() {
 	case reflect.Bool:
 		x, ok := val.(*pb.Value_BooleanValue)

firestore/to_value.go

@@ -15,6 +15,7 @@
 package firestore
 
 import (
+	"encoding"
 	"errors"
 	"fmt"
 	"reflect"
@@ -30,11 +31,12 @@ import (
 var nullValue = &pb.Value{ValueType: &pb.Value_NullValue{}}
 
 var (
-	typeOfByteSlice      = reflect.TypeOf([]byte{})
-	typeOfGoTime         = reflect.TypeOf(time.Time{})
-	typeOfLatLng         = reflect.TypeOf((*latlng.LatLng)(nil))
-	typeOfDocumentRef    = reflect.TypeOf((*DocumentRef)(nil))
-	typeOfProtoTimestamp = reflect.TypeOf((*ts.Timestamp)(nil))
+	typeOfByteSlice       = reflect.TypeOf([]byte{})
+	typeOfGoTime          = reflect.TypeOf(time.Time{})
+	typeOfLatLng          = reflect.TypeOf((*latlng.LatLng)(nil))
+	typeOfDocumentRef     = reflect.TypeOf((*DocumentRef)(nil))
+	typeOfProtoTimestamp  = reflect.TypeOf((*ts.Timestamp)(nil))
+	typeOfTextUnmarshaler = reflect.TypeOf(new(encoding.TextUnmarshaler)).Elem()
 )
 
 // toProtoValue converts a Go value to a Firestore Value protobuf.
@@ -91,6 +93,12 @@ func toProtoValue(v reflect.Value) (pbv *pb.Value, sawTransform bool, err error)
 		// types whose underlying types are those primitives.
 		// E.g. Given "type mybool bool", an ordinary type switch on bool will
 		// not catch a mybool, but the reflect.Kind of a mybool is reflect.Bool.
+	case encoding.TextMarshaler:
+		text, err := x.MarshalText()
+		if err != nil {
+			return nil, false, err
+		}
+		return &pb.Value{ValueType: &pb.Value_StringValue{string(text)}}, false, nil
 	}
 	switch v.Kind() {
 	case reflect.Bool:

firestore/to_value_test.go

@@ -218,6 +218,11 @@ func TestToProtoValue_Conversions(t *testing.T) {
 			in:   [1]int{7},
 			want: arrayval(intval(7)),
 		},
+		{
+			desc: "encodingText",
+			in:   encodingText{},
+			want: strval("encodingText"),
+		},
 		{
 			desc: "pointer to docref",
 			in: &DocumentRef{
@@ -312,6 +317,14 @@ type stringy struct{}
 
 func (stringy) String() string { return "stringy" }
 
+type encodingText struct {
+	text string
+}
+
+func (_ encodingText) MarshalText() ([]byte, error) {
+	return []byte(`encodingText`), nil
+}
+
 func TestToProtoValue_Errors(t *testing.T) {
 	for _, in := range []interface{}{
 		uint64(0),                               // a bad fit for int64