Use wrapper to treat fmt.String as pgtype.TextValuer

pgtype/builtin_wrappers.go

@@ -491,3 +491,11 @@ func (w mapStringToStringWrapper) HstoreValue() (Hstore, error) {
 	}
 	return hstore, nil
 }
+
+type fmtStringerWrapper struct {
+	s fmt.Stringer
+}
+
+func (w fmtStringerWrapper) TextValue() (Text, error) {
+	return Text{String: w.s.String(), Valid: true}, nil
+}

pgtype/enum_codec.go

@@ -30,8 +30,6 @@ func (EnumCodec) PlanEncode(ci *ConnInfo, oid uint32, format int16, value interf
 			return encodePlanTextCodecByteSlice{}
 		case rune:
 			return encodePlanTextCodecRune{}
-		case fmt.Stringer:
-			return encodePlanTextCodecStringer{}
 		case TextValuer:
 			return encodePlanTextCodecTextValuer{}
 		}

pgtype/pgtype.go

@@ -1421,6 +1421,8 @@ func tryWrapBuiltinTypeEncodePlan(value interface{}) (plan WrappedEncodePlanNext
 		return &wrapMapStringToPointerStringEncodePlan{}, mapStringToPointerStringWrapper(value), true
 	case map[string]string:
 		return &wrapMapStringToStringEncodePlan{}, mapStringToStringWrapper(value), true
+	case fmt.Stringer:
+		return &wrapFmtStringerEncodePlan{}, fmtStringerWrapper{value}, true
 	}
 
 	return nil, nil, false
@@ -1616,6 +1618,16 @@ func (plan *wrapMapStringToStringEncodePlan) Encode(value interface{}, buf []byt
 	return plan.next.Encode(mapStringToStringWrapper(value.(map[string]string)), buf)
 }
 
+type wrapFmtStringerEncodePlan struct {
+	next EncodePlan
+}
+
+func (plan *wrapFmtStringerEncodePlan) SetNext(next EncodePlan) { plan.next = next }
+
+func (plan *wrapFmtStringerEncodePlan) Encode(value interface{}, buf []byte) (newBuf []byte, err error) {
+	return plan.next.Encode(fmtStringerWrapper{value.(fmt.Stringer)}, buf)
+}
+
 // Encode appends the encoded bytes of value to buf. If value is the SQL value NULL then append nothing and return
 // (nil, nil). The caller of Encode is responsible for writing the correct NULL value or the length of the data
 // written.

pgtype/text.go

@@ -100,8 +100,6 @@ func (TextCodec) PlanEncode(ci *ConnInfo, oid uint32, format int16, value interf
 			return encodePlanTextCodecByteSlice{}
 		case rune:
 			return encodePlanTextCodecRune{}
-		case fmt.Stringer:
-			return encodePlanTextCodecStringer{}
 		case TextValuer:
 			return encodePlanTextCodecTextValuer{}
 		}

pgtype/text_test.go

@@ -9,6 +9,12 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+type someFmtStringer struct{}
+
+func (someFmtStringer) String() string {
+	return "some fmt.Stringer"
+}
+
 func TestTextCodec(t *testing.T) {
 	for _, pgTypeName := range []string{"text", "varchar"} {
 		testPgxCodec(t, pgTypeName, []PgxTranscodeTestCase{
@@ -24,6 +30,7 @@ func TestTextCodec(t *testing.T) {
 			},
 			{nil, new(pgtype.Text), isExpectedEq(pgtype.Text{})},
 			{"foo", new(string), isExpectedEq("foo")},
+			{someFmtStringer{}, new(string), isExpectedEq("some fmt.Stringer")},
 			{rune('R'), new(rune), isExpectedEq(rune('R'))},
 		})
 	}