How to integrate photo uploading code to member registration form

Question

(I've removed working code part such as controller file and javascript to minimize question size as suggested in the chat. And I can add if required by anyone)

I followed this tutorial to upload image (worked successfully with some syntax modification). But when I integrated the code to member registration form, everything upto image preview is working, but photo is not uploading to the predefined directory.

Working part of code

uploadfile.html.erb

<h1>File Upload</h1>
<%= form_tag({:action => 'uploadFile'}, :multipart => true) do %>
<p><label for="upload_file">Select File</label> <%= file_field 'upload', 'datafile', :class => 'filen btn btn-danger'%></p>
<div class="upload-preview">
<img alt="your image"/>
</div>
<br><br />
<%= submit_tag "Upload" %>
<% end %>

Not working part of code (only uploading part. Works fine upto previewing image)

Now I integrate this code with my member reg form as below, by copy pasting form_tag contents without {} brackets in form_for to convert form_tag to form_for.

_form.html.erb

<div class="input-group">
<%= form_for(@member, :action => 'uploadFile', :multipart => true) do |f| %>
  
<p><label for="upload_file">Select File</label> <%= file_field 'upload', 'datafile', :class => 'filen btn btn-danger'%></p>
<div class="upload-preview">
<img alt="your image"/>
</div>

  <div class="field">
    <%= f.label :member_code %><br>
    <%= f.text_field :member_code %>
  </div>



So many fields and labels


  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>
</div>

members_controller.rb (Here, I copy paste the def uploadFile part from upload_controller.rb)

  def index
    @members = Member.all
  end
def uploadFile
    post = Member.save(params[:upload])
    render :text => "File has been uploaded successfully"
  end

  def member_params
    params.require(:member).permit(:member_code, :emp_code, :name, :father_name, :dob, :doe, :age, :caste, :religion, :residing_year, :nominee, :relation, :income_amt, :permanent, :off_add1, :off_add2, :off_add3, :mem_cancellation, :no_shares, :registration_date, :share_amt, :salary_head, :record_status, :sex, :mem_any_society, :occupation, :application_no, :dor, :kannada_name, :date_of_death, :date_of_inactive, :res_kan_add1, :res_kan_add2, :res_kan_add3, :kannada_nominee)
  end
end

The preview part somehow working without creating new javascript file for member model.

From what I understand, When I press create member button, the file is not uploading to the predifined public/data directory. Even after I mention :action => 'uploadFile', in the view, why it is not working, when other things up-to preview image works fine. I think I have to add upload inside create action itself, but don't know what exactly to add. Please help me.