Input type = "file" loses file automatically? - html

Question

I have two inputs of type file, one in a partial view, and another in main page
In partial view
<input type="file" name="image" id="image" onchange="readURL(this)"/>
In main page
<input type="file" name="userProfilePic" id="userProfilePic" style="display:none" />
What I want is that when a user changes image/file on the visible file upload, the image/file should be updated on main/other input too. Here's my code.
function readURL(input) {
if (input.files && input.files[0]) {
var reader = new FileReader();
reader.onload = function (e) {
$('#imagePreview').attr('src', e.target.result);
}
reader.readAsDataURL(input.files[0]);
// window['profilePic'] = input.files[0];
$('#userProfilePic').get(0).files[0] = input.files[0];
return false;
}
The Error
The error is quite weird, when I open my console, and check for files, it shows up sometime, and a moment later it don't.
In my console window
$('#userProfilePic').get(0).files[0]
File (file object details)
....
(after a second)
$('#userProfilePic').get(0).files[0]
undefined
And it isn't happening the first time only. Say sometimes, it shows the values for 5-6 times, then 7th time it won't...
$('#userProfilePic').get(0).files[0]
File (file object details)
....
(after a second)
$('#userProfilePic').get(0).files[0]
File (file object details)
....
(after a second)
$('#userProfilePic').get(0).files[0]
File (file object details)
....
(after a second)
$('#userProfilePic').get(0).files[0]
undefined
That's all the code I have, there is no other code. Now, as you can see in the code, I also set window[profilePic] to the file object. But if I check that in console window, it always shows no matter what? How is this happening?
The problem
I need to submit the form, but when I do, the image (the input file) is being sent as null, but sometimes as a valid file. As I explained earlier, when I check the value in console, it shows for first time, or some random number of times, then all of a sudden it is gone, while the variable that I set on window (window[profilePic]) always have that file object.
In case someone is wondering, the original/visible file input where user actually selects the file always has the value.

Answer 1

You cant do this for security reasons , all files uploaded via input type="file" have to be done manually by the user.
However as long as the user will upload an image anyway , you should do all the process you want in your server side script.
for further info , please refer to this post here :
How to set a value to a file input in HTML?

Answer 2

Why you try to use two inputfile for the same file?
if you try to make a form in a PartialView with a inputfile and extra data? I answered a very similar question here:
File upload in MVC when used in bootstrap modal returns null
1) make a model for used in the form with all elements for the form,
2) declare the model in the first line in the partial view
3) pass as parameter the model to the post function.
4) you use a Partial view, well is possible use this view in differents pages, you need specify the control to treatement the form.
An Example in code:
Model:
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
public class PartialFormModel
{
[Required]
[StringLength(200)]
public string FileName { get; set; }
[StringLength(200)]
public string Title { get; set; }
[StringLength(1000)]
public string Description { get; set; }
public int? Order { get; set; }
[NotMapped]
public HttpPostedFileBase ImageFile { get; set; }
}
PartialVIEW:
#model YOURSPACENAME.Models.PartialFormModel
#using (Html.BeginForm("YourActionName", "YourControllerName", FormMethod.Post, new { #class = "form-horizontal", #role = "form", #enctype="multipart/form-data" }))
{
#Html.AntiForgeryToken()
<div class="form-group">
#Html.LabelFor(model => model.FileName, htmlAttributes: new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.EditorFor(model => model.FileName, new { htmlAttributes = new { #class = "form-control" } })
#Html.ValidationMessageFor(model => model.FileName, "", new { #class = "text-danger" })
</div>
</div>
<div class="form-group">
#Html.LabelFor(model => model.ImageFile, new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.TextBoxFor(m => m.ImageFile, new { #class = "form-control", type = "file" })
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
}
CONTROLLER
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult YourActionName(PartialFormModel obj)
{
if (ModelState.IsValid)
{
//your options
}
return PartialView("_EditSlider");
}

Answer 3

Considering that:
For security reasons you can't set value of input type="file"
programmatically.
Changing the type of an <input> throws a security error in some
browsers (old IE and Firefox versions).
I don't know actually what you want. But I exhort you to create a new input element, set its type to the one you want, say file, and set its properties according to your need. like this:
<script>
function createInputType(_type, _value, _name, _id, _class) {
var newObject = document.createElement('input');
newObject.type = _type;
newObject.value = _value;
newObject.name = _name;
newObject.id = _id;
newObject.className = _class;
return newObject;
}
</script>