Zend View Helper中的数据库连接

Question

Is it a good practice to use database mappers in Zend View Helper? Because in my case this helper is making me a box of <div> that keeps changing in real time and is to be shown in all the views there are in my application. I can not possibly give that object loading it from the database in controllers and assign it to view everytime.

It would be really helpful if someone could tell good programming practices to follow when working with zend view helpers like:

• If it is OK to assign something to the view in the View Helpers by $this->view->variable = ... ;
• If it is OK to create and use models in View Helpers.
• If it is OK to use methods available to Zend_View inside a View Helper like by doing $this->view->baseUrl('...');

Answer 1

Your second and third bullet points seem correct to me, as long as you don't do any logical stuff in your model from your views. The link between models and views must be read-only.

Concerning your first point, you don't need to assign anything to the view, you view helper should return your HTML output directly to the view.

About your first question, you could create View Helper that is specialized in this task, so you can use it as a simple proxy between your view helpers and mappers. One view helper will allow you to access to any mapper, and others view helpers can use this view helper to get a mapper.

Let's see what Trygve Reenskaug thinks about MVC:

Models

Models represent knowledge. A model could be a single object (rather uninteresting), or it could be some structure of objects.

There should be a one-to-one correspondence between the model and its parts on the one hand, and the represented world as perceived by the owner of the model on the other hand.

Views

A view is a (visual) representation of its model. It would ordinarily highlight certain attributes of the model and suppress others. It is thus acting as a presentation filter.

A view is attached to its model (or model part) and gets the data necessary for the presentation from the model by asking questions. It may also update the model by sending appropriate messages. All these questions and messages have to be in the terminology of the model, the view will therefore have to know the semantics of the attributes of the model it represents.

Controllers

A controller is the link between a user and the system. It provides the user with input by arranging for relevant views to present themselves in appropriate places on the screen. It provides means for user output by presenting the user with menus or other means of giving commands and data. The controller receives such user output, translates it into the appropriate messages and pass these messages on to one or more of the views.