'Renders the right key constraint in a link table as
S3EmbeddedComponentWidget and stores the postprocess hook.
@param resource: the link table resource'

def _embed_component(self, resource, record=None):

    link = None
    component = resource.linked
    if ((component is not None) and (component.actuate == 'embed')):
        ctablename = component.tablename
        attr = {'link': resource.tablename, 'component': ctablename}
        autocomplete = component.autocomplete
        if (autocomplete and (autocomplete in component.table)):
            attr['autocomplete'] = autocomplete
        if (record is not None):
            attr['link_filter'] = ('%s.%s.%s.%s.%s' % (resource.tablename, component.lkey, record, component.rkey, component.fkey))
        rkey = component.rkey
        if (rkey in resource.table):
            field = resource.table[rkey]
            field.widget = S3EmbeddedComponentWidget(**attr)
            field.comment = None
        callback = self._postprocess_embedded
        postprocess = (lambda form, key=rkey, component=ctablename: callback(form, key=key, component=component))
        link = Storage(postprocess=postprocess)
    return link
