How to allow a related model in Yii to be empty?

Within the 'rules' function of the Book model you should see something like this.

You could import your authors first, but this would probably wouldn't work either since your csv won't have the author_id in it.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.