How to use the pyramid.view.view_config function in pyramid

    @view_config(route_name='iam_policy_create', renderer=TEMPLATE, request_method='POST')
    def iam_policy_create(self):
        """Handles the POST from the Create IAM Policy wizard"""
        target_route = '{0}_view'.format(self.target_type)  # 'user_view' or 'group_view'
        location = self.request.route_url(target_route, name=self.target_name)  # redirect to detail page after submit
        if self.create_form.validate():
            policy_name = self.request.params.get('name')
            policy_json = self.request.params.get('policy', '{}')
            try:
                if self.target_type == 'user':
                    caller = self.iam_conn.put_user_policy
                else:
                    caller = self.iam_conn.put_group_policy
                caller(self.target_name, policy_name, policy_json)
                prefix = _(u'Successfully created IAM policy')
                msg = '{0} {1}'.format(prefix, policy_name)
                queue = Notification.SUCCESS

@view_config(name='upload', context=File, request_method='GET',
             permission='edit')
def get_upload(context, request):
    external = context.propsheets.get('external', {})
    upload_credentials = external.get('upload_credentials')
    # Show s3 location info for files originally submitted to EDW.
    if upload_credentials is None and external.get('service') == 's3':
        upload_credentials = {
            'upload_url': 's3://{bucket}/{key}'.format(**external),
        }
    return {
        '@graph': [{
            '@id': request.resource_path(context),
            'upload_credentials': upload_credentials,
        }],

    @view_config(name="user", subpath=("username/*"), request_method="DELETE")
    def delete_user(self):
        """ Delete a user """
        username = self.request.named_subpaths["username"]
        self.request.access.delete_user(username)
        return self.request.response

    @view_config(name='add_document', context=Folder)
    def add_document(self):
        # Make a new Document
        title = self.request.POST['document_title']
        name = str(randint(0, 999999))
        new_document = Document(name, self.context, title)
        self.context[name] = new_document

        # Redirect to the new document
        url = self.request.resource_url(new_document)
        return HTTPFound(location=url)

    @view_config(route_name='tree_invalidate', renderer='json', accept='application/json', permission='edit')
    def invalidate_tree(self):
        invalidate_cache()
        return Response(status_int=200)

@view_config(route_name='admin_data_histogram_dayssincepurchase',
             renderer='json',
             permission='manage')
def admin_data_histogram_dayssincepurchase(request):
    return user_dayssincepurchase_histogram()

    @view_config(route_name='scalinggroup_history', renderer=TEMPLATE, request_method='GET')
    def scalinggroup_history(self):
        return self.render_dict

@view_config(
    route_name='view_tasks',
    renderer='templates/task/view_tasks.jinja2',
    permission='View_Task'
)
def view_tasks(request):
    """runs when viewing tasks of a TaskableEntity
    """
    login = authenticated_userid(request)
    logged_in_user = User.query.filter_by(login=login).first()
    
    entity_id = request.matchdict['entity_id']
    entity = Entity.query.filter(Entity.id==entity_id).first()
    
    return {
        'entity': entity
    }

    @view_config(name="add_folder", context=Folder)
    def add_folder(self):
        # Make a new Folder
        title = self.request.POST['folder_title']
        name = str(randint(0, 999999))

        new_folder = Folder(title=title)
        DBSession.add(new_folder)
        self.context[name] = new_folder

        # Redirect to the new folder
        url = self.request.resource_url(new_folder)
        return HTTPFound(location=url)

    @view_config(
        name='details',
        request_method='GET',
        renderer='travelcrm:templates/calculations/details.mako',
        permission='view'
    )
    def details(self):
        calculation = Calculation.get(self.request.params.get('id'))
        contract_resource = None
        if calculation.contract:
            resource_cls = get_resource_class(
                calculation.contract.resource.resource_type.name
            )
            contract_resource = resource_cls(self.request)
        return {
            'item': calculation,
            'contract_resource': contract_resource