which field type is the best for an order ?

[adrianmak]

I'm going to build a simple e-commerce website.

I knew there ise-commerce pw module to do the job.

I want to build it from scratch.

One of a page template will be order. An order may have more than one product item

Which field type (repeaters, page, any others ?) is the best for repeating item on this case.

[horst]

I think you can use what you best like. If you are comfortable with repeaters, you can use this. If you are more comfortable with others, use others.

But I cannot understand why you want to do it from scratch, if your questions already start at this early point? Is this a free project, that you want build just for learning, or is this a productional project for a client?

[kixe]

Follow the slogan "Everything in PW is a page". To stay flexible I would store orders and order items as pages.
Use PageFieldEditLinks together with PageFields (ASM Select) to handle/ edit the Page Fields comfortably.