How to allow formData sends null - ajax

Question

I have a form it works fine if i fill all fields, but if i don't fill attachment field it returns error says: The attachment must be a file of type: image/jpeg, image/png. while my attachment is nullable in back-end validator.
code
backend
public function sendEmail(Request $request) {
$this->validate($request, array(
'body' => 'required',
'subject' => 'required',
'receivers' => 'required',
'project_id' => 'required',
'attachment' => 'nullable|mimetypes:image/jpeg,image/png|max:2048',
));
if ($request->hasFile('attachment')) {
$request->validate([
'attachment' => 'nullable|mimetypes:image/jpeg,image/png|max:2048',
]);
$image = $request->file('attachment');
$filename = 'attachment-' . str_random(10) . '-' . time() . '.' . $image->getClientOriginalExtension();
$location = public_path('images/'. $filename);
// $request->file('photo')->move(public_path('images') . $filename);
$request->file('attachment')->storeAs('attachment', $filename);
$attachment = $filename;
} else {
$attachment = null;
}
//rest of function
}
Ajax
$('body').on('click','.sendMailNowSubmit',function(e) {
e.preventDefault();
$(this).text('Please wait ...');
var formData = new FormData();
formData.append('body', $('#messageBody').val());
formData.append('subject', $('#messageSubject').val());
formData.append('receivers', $('#receivers').val());
formData.append('project_id', $(this).data('id'));
formData.append('attachment', $('input[type=file]')[0].files[0]);
$.ajax({
type:'POST',
url:'{{route('sendEmail')}}',
data: formData,
async: false,
cache: false,
contentType: false,
dataType: 'JSON',
enctype: 'multipart/form-data',
processData: false,
success:function(data){
$(".sendMailNow").attr("disabled", false);
document.getElementById("sendMailForm").reset();
$(".Mailmessage").append('<div class="alert alert-success fade in">'+data.success+'</div>').hide(4000);
$(".sendMailModal").modal('hide');
$(".sendMailNowSubmit").val("Done!");
$(".sendMailNowSubmit").text('Submit');
},
error: function(data){
$(".sendMailNow").attr("disabled", false);
var errors = data.responseJSON;
errorsHtml = '<div class="alert alert-danger alert-dismissible">×<ul>';
$.each(errors.errors,function (k,v) {
errorsHtml += '<li>'+ v + '</li>';
});
errorsHtml += '</ul></di>';
$( '.Mailmessage' ).html( errorsHtml );
$(".sendMailNowSubmit").text('Re-Submit');
}
});
});
Any idea?

Answer 1

Try this code for validation
$rules = [
'body' => 'required',
'subject' => 'required',
'receivers' => 'required',
'project_id' => 'required'
];
if ($request->hasFile('attachment')) {
$rules['attachment'] = 'mimetypes:image/jpeg,image/png|max:2048';
}
$this->validate($request, $rules);