added a FileTag and made sure the form automatically flips to multipart

form/file_tag.go

@@ -0,0 +1,13 @@
+package form
+
+import "github.com/gobuffalo/tags"
+
+func (f Form) FileTag(opts tags.Options) *tags.Tag {
+	if opts["type"] == nil {
+		opts["type"] = "file"
+	}
+	if opts["type"] == "file" {
+		f.Options["enctype"] = "multipart/form-data"
+	}
+	return f.InputTag(opts)
+}

form/input_tag.go

@@ -6,6 +6,9 @@ func (f Form) InputTag(opts tags.Options) *tags.Tag {
 	if opts["type"] == nil {
 		opts["type"] = "text"
 	}
+	if opts["type"] == "file" {
+		f.Options["enctype"] = "multipart/form-data"
+	}
 	return tags.New("input", opts)
 }
 

form/input_tag_test.go

@@ -28,3 +28,11 @@ func Test_Form_DateTimeTag(t *testing.T) {
 	})
 	r.Equal(`<input type="datetime-local" value="1976-08-24T06:17" />`, i.String())
 }
+
+func Test_Form_InputTag_File(t *testing.T) {
+	r := require.New(t)
+	f := form.New(tags.Options{})
+	i := f.InputTag(tags.Options{"type": "file"})
+	r.Equal(`<input type="file" />`, i.String())
+	r.Equal(f.Options["enctype"], "multipart/form-data")
+}