how to use codeigniter database models

I am wondering how the models in code ignitor are suposed to be used.

Lets say I have a 开发者_高级运维couple of tables in menu items database, and I want to query information for each table in different controllers. Do I make different model classes for each of the tables and layout the functions within them?

Thanks!

Models should contain all the functionality for retrieving and inserting data into your database. A controller will load a model:

$this->load->model('model_name');

The controller then fetches any data needed by the view through the abstract functions defined in your model.

It would be best to create a different model for each table although its is not essential.

You should read up about the MVC design pattern, it is used by codeigniter and many other frameworks because it is efficient and allows code reuse. More info about models can be found in the Codeigniter docs:

http://codeigniter.com/user_guide/general/models.html

CodeIgniter is flexible, and leaves this decision up to you. The user's guide does not say one way or the other how you should organize your code.

That said, to keep your code clean and easy to maintain I would recommend an approach where you try to limit each model to dealing with an individual table, or at least a single database entity. You certainly want to avoid having a single model to handle all of your database tables.

For my taste, CodeIgniter is too flexible here - I'd rather call it vague. A CI "model" has no spec, no interface, it can be things as different as:

• An entity domain object, where each instance represents basically a record of a table. Sometimes it's an "anemic" domain object, each property maps directly to a DB column, little behaviour and little or no understanding of objects relationships and "graphs" (say, foreign keys in the DB are just integer ids in PHP). Or it can also be a "rich (or true) domain object", with all the business intelligence, and also knows about relations: say instead of $person->getAccountId() (returns int) we have $person->getAccount(); perhaps also knows how to persist itself (and perhaps also the full graph or related object - perhaps some notion of "dirtiness").

• A service object, related to objects persistence and/or general DB querying: be a DataMapper, a DAO, etc. In this case we have typically one single instance (singleton) of the object (little or no state), typically one per DB table or per domain class.

When you read, in CI docs or forums, about , say, the Person model you can never know what kind of patter we are dealing with. Worse: frequently it's a ungly mix of those fundamentally different patterns.

This informality/vagueness is not specific to CI, rather to PHP frameworks, in my experience.