var Lifnr = this.getView().getModel("vendorDiaolog").getProperty("Lifnr", path);
Because you are setting your json model with the name "vendorDialog", so you need to call its name when you want to get it.
var Lifnr = this.getView().getModel("vendorDiaolog").getProperty("Lifnr", path);
Because you are setting your json model with the name "vendorDialog", so you need to call its name when you want to get it.