This Wiki article: Adding a Product to the Cart via Querystring describes how one can put product with specific id to the cart directly from querystring. So for simple product it would be something like this:
/path/to/app/checkout/cart/add?product=[id]&qty=[qty]
But after it adds a product, Magento redirects browser to the home page and shows nice message that product has been added successfully. But we need to show a Shopping Cart directly, not a home page. So maybe it is possible to add another param to the querystring to achieve this?
I know I could write a module, but I just stumbled upon this possibility, so might be there is a way to easily redirect as well?
There a few things you could try before going the custom code route.
In the Admin UI you could make sure the redirect flag is correct.
If that doesn’t solve the problem, try this one.