How to create and display an image in ode

I need help with a bug in odoo. I created models and xml for image in odoo.

these are my models

class Test(osv.osv):
_name = "digital.test"
_description = "Test"

_columns = {
    'Servicename': fields.char('Service Name'),
    'prodescription': fields.html('Product description'),
    'Subservicename': fields.char('Sub-Service Name'),
    'subprodescription': fields.html('Product Desc.'),
}

# image: all image fields are base64 encoded and PIL-supported
image = openerp.fields.Binary("Photo", attachment=True,
    help="This field holds the image used as photo for the test, limited to 1024x1024px.")
image_medium = openerp.fields.Binary("Medium-sized photo", attachment=True,
    help="Medium-sized photo of the test. It is automatically "\
         "resized as a 128x128px image, with aspect ratio preserved. "\
         "Use this field in form views or some kanban views.")
image_small = openerp.fields.Binary("Small-sized photo", attachment=True,
    help="Small-sized photo of the test. It is automatically "\
         "resized as a 64x64px image, with aspect ratio preserved. "\
         "Use this field anywhere a small image is required.")

def _get_default_image(self, cr, uid, context=None):
    image_path = get_module_resource('mymodule', 'static/src/img', 'default_image.png')
    return tools.image_resize_image_big(open(image_path, 'rb').read().encode('base64'))

defaults = {
    'active': 1,
    'image': _get_default_image,
    'color': 0,
}

@api.model
def create(self, vals):
    tools.image_resize_images(vals)
    return super(digital.test, self).create(vals)

      

        
        
        
      

    

and this is my xml

        <record id="view_test_form" model="ir.ui.view">
        <field name="name">digital.test.form</field>
        <field name="model">digital.test</field>
        <field name="arch" type="xml">
            <form string="Test">
                <sheet>
                    <field name="image" widget='image' class="oe_avatar" options='{"preview_image":"image_medium"}'/>
                    <div class="oe_title">
                        <label for="Service Name" class="oe_edit_only"/>
                        <h1>
                            <field name="Servicename" placeholder="Service Name"/>
                        </h1>
                    </div>
                    <notebook>
                        <page string="Product Description">
                            <group string="Service Name">
                                <field name="prodescription" type="html"/>
                            </group>
                            <group string="Sub-Service Name">
                                  <field name="Subservicename"/>
                                  <field name="subprodescription" widget="html"/>
                            </group>
                        </page>
                    </notebook>
                </sheet>
            </form>
        </field>
    </record>

      

        
        
        
      

    

But my code is error while creating new data like this enter image description here

I can save data when I delete @ api.model def create but my image cannot save.

thank