I made a web form where user enter his informations and upload a file then submit everything , when the action submit occurs the user data will be stored in candidate record , everything is working fine except for the file uploaded , it doesnt appear in the candidate record as if the user hasnt uploaded any file

I have a model named candidate where I have 

candidate.py

attachment_ids = fields.Many2many(string="Attachment")

and in candidate_views.xml I have

<record model="ir.ui.view" id="candidate_form_view">
  <field name="name">candidate Form</field>
  <field name="model">university.candidate</field>
  <field name="arch" type="xml">
    <form>
      <group>
         <field name="f_name"/>
        <field name="l_name"/>

       field name="attachment_ids" widget="many2many_binary" />


      </group>

    </form>
  </field>
</record>

and in the conrollers/main.py I have

@http.route(['/my/account'], type='http', auth='public', website=True)
def account(self, redirect=None, **post):


    Attachments = request.env['university.candidate']
    name = post.get('attachment').filename
    file = post.get('attachment')
    attachment_id = Attachments.create({
        'name': name,
        'type': 'binary',
        'datas': base64.b64encode(file.read())

    })
    partner.update({
        'attachment': [(3, attachment_id.id)],
    })

and in the website_form.xml I have

<form action="/my/account" method="post" enctype="multipart/form-data">

 <div class="form-group">
 <div class="col-lg-3 col-md-4 text-right">
 <label class="col-form-label" for="attachment_ids">Attachment(s)</label>
 </div>
 <div class="col-lg-7 col-md-8">
 <input type="file" name="attachment_ids" multiple="true"
 accept="image/*,application/pdf,video/*"/>
 </div>
 </div>
 </form>