I have this on my website:

I try to update the product image (image_medium) on a product.id

Here is my code (xml):

<div class="form-group" style="margin-left: 14px;">

    <img itemprop="image" class="img img-responsive" t-att-src="website.image_url(product, 'image_medium', None if product_image_big else '300x300')"/>
    <input class="input-file profileChooser" id="fileInput" type="file" name="image_medium" onchange="validateProfileImg();"/>


</div>

(controller):

@http.route(['/my/test/<int:product>'], type='http', auth="user", website=True)
def products_followup(self, product=None, redirect=None, **post):
product = request.env['product.template'].browse([product])
    try:
        product.check_access_rights('read')
        product.check_access_rule('read')
    except AccessError:
            return request.website.render("website.403")
    values = {
        'error': {},
        'error_message': [],
         }
    if post:

        vals = {}
        if post['image_medium']:
            values.update({'image': base64.encodestring(post['image_medium'].read())})
        request.registry['product.template'].write(request.cr, request.uid, [product.id], vals)
        product.sudo().write(post)
        values.update(post)
        if redirect:
            return request.redirect(redirect)
        return request.redirect('/my/home')

    return request.website.render("website_portal_sale.products_followup", {
        'product': product.sudo(),
    })

Now when I post the image (local file) , I get this error:

AttributeError: 'file' object has no attribute 'decode'

Can someone help me?

thank you.