I created a class with an image field

        'image': fields.binary("Image",),

I added the "image" widget on the xml view file

   <field name="image" widget='image' class="oe_avatar oe_left" options='{"preview_image": "image_medium"}'/>

The image placeholder appeared successfully on the view when I upgraded the module, but when I select an image and save the screen nothing is saved, what is missing?, pls help