Something what could surprise you when you work with web parts in Office 365 is missing option of web part connection. We put web part on the page base on existing list and we will see something like this:

Web Part

There’s no options to make connection to our web part. Why? To make possible web part connection you have to have possibility to data exchange, and default static state is blocking it. To solve the problem we have to select “Edit web part”. We should see screen like this:

Ajax Options

To force web part using connections we have select “Enable Asynchronous Update”

Enable Asynchronous Update

After applying this option connections will appear on the our web part:

Connection