SAPUI5 OData - create_deep_entity

[#1]

I'm working on a Master Detail PO receipt app.

In the detail page, I have a button (sbmit) supposed to execute the code in the create_deep_entity method.

I want to know how to get the values entered by the user (Header entity and Items entity) and then how to call the create_deep_entity method.

In the function for pressing the Approve button, I put:

var oPOHeader = this.getView().getModel().getData()

But it's returning null.

Any ideas on how to achieve this ?

Thanks in advance.