如何使用布尔逻辑validate_presence_of？

Suppose I am entering validation code into my model of multi-language publication database. The database needs either an English or a Japanese title for a particular journal. So I need to validate_presence_of at least one of the two. Right now I can easily check that both exists, but am stumped on the case of "at least one":Suppose I am entering validation code into my m