title: file control doesn't initialized in edit page - razor pages
body: <p>I use asp.net core razor pages to create my application, in my create page, I have two file controls, one for upload icon image and the other for uploading detail images. But when I click edit button, all of the fields were initialized, except the two file controls. Please check my code. Anyone can help?</p>
  
  <p>In my razor page:</p>
  
  <pre><code>&lt;div class="row"&gt;
                  &lt;div class="col-md-6"&gt;
                      &lt;div class="form-group"&gt;
                          &lt;label asp-for="Product.Icon" class="control-label"&gt;&lt;/label&gt;
                          &lt;input asp-for="@Model.Icon" type="file" /&gt;
                          &lt;span asp-validation-for="Product.Icon" class="text-danger"&gt;&lt;/span&gt;
                      &lt;/div&gt;
                  &lt;/div&gt;
                  &lt;div class="col-md-6"&gt;
                      &lt;div class="form-group"&gt;
                          &lt;label class="control-label”&gt;Detail Images（support multi-uploading）：&lt;/label&gt;
                          &lt;input type="file" id="fUpload" name="files" multiple /&gt;
                      &lt;/div&gt;
                  &lt;/div&gt;
              &lt;/div&gt;
  </code></pre>
  
  <p>In my page model:</p>
  
  <pre><code>  public async Task&lt;IActionResult&gt; OnGetAsync(int? id)
          {
              if (id == null)
              {
                  return NotFound();
              }
              Product = await _context.Products
                  .Include(p =&gt; p.Shop).SingleOrDefaultAsync(m =&gt; m.ID == id);
              if (Product == null)
              {
                  return NotFound();
              }
              ViewData["Shop"] = new SelectList(_context.Shops, "ID", "Name");
              return Page();
          }
          public async Task&lt;IActionResult&gt; OnPostAsync(List&lt;IFormFile&gt; files)
          {
              if (!ModelState.IsValid)
              {
                  return Page();
              }
              var uploads = Path.Combine(hostingEnvironment.WebRootPath, "uploads");
              if (!Directory.Exists(uploads))
              {
                  Directory.CreateDirectory(uploads);
              }
              if (this.Icon != null)
              {
                  var fileName = GetUniqueName(this.Icon.FileName);
                  var filePath = Path.Combine(uploads, fileName);
                  this.Icon.CopyTo(new FileStream(filePath, FileMode.Create));
                  this.Product.Icon = fileName;
              }
              if (files != null &amp;&amp; files.Count &gt; 0)
              {
                  foreach (IFormFile item in files)
                  {
                      if (item.Length &gt; 0)
                      {
                          var fn = GetUniqueName(item.FileName);
                          var fp = Path.Combine(uploads, fn);
                          item.CopyTo(new FileStream(fp, FileMode.Create));
                          this.Product.ProductImages = this.Product.ProductImages + fn + "^";
                      }
                  }
              }
              _context.Attach(Product).State = EntityState.Modified;
              try
              {
                  await _context.SaveChangesAsync();
              }
              catch (DbUpdateConcurrencyException)
              {
                  if (!ProductExists(Product.ID))
                  {
                      return NotFound();
                  }
                  else
                  {
                      throw;
                  }
              }
              return RedirectToPage("./Index");
          }
  </code></pre>