How to communicate between child control and parent window with big hierarchy in wpf?

Question

There is big hierarchy of controls: window , inside window there is control, inside one more... All of them have view models. Before creating parent window , i generate some Field and pass as parameter of the window. I need to display the field on child control, how i can pass this field from parent's window view model to child control's view model not using the chain of properties/events/delegate commands and using mvvm ? What about ways to communicate between parent window and child control if there are many layers between?

Answer 1

The number of layers in between should be irrelevant if you follow the MVVM pattern. If for example all can happen in a single view model then there should be no issue. If however you have a separate view models as context for the window and a specific control, then it would be a good idea that the relationship gets reflected on the view model side, having the top view model contain the bottom one for example.