I am currently facing following problem:
I would like to have full-custom form for custom object. I cannot use standard Lightning Record Page, because there are lot of customisations like some fields showing up conditionally based on other fields' values, custom buttons changing statuses, popups with additional options, etc.
Also, the record is related to Account, Lead and Opportunity. User needs to create this custom object from all of them. When doing so, proper lookup needs to be populated, also some other fields have values copied from them.
Now the problem: I have overriden the NEW action with my custom Lightning Component. However, I cannot find a way to prepopulate certain fields when creating this object from related list. Any ideas how to do it?
P.S. I already have working solution using Lightning out VF page that is passing prepopulation parameters to my Lightning Component. However, it's hard for me to believe SF have not thought about pure-LEX solution for such use case!