rails控制器索引渲染验证

Question

如何让它发挥作用？

books_controller.rb：

1）

def index
  @books = Book.where(library_id.present?)
end

2）

def warsaw_books
  @books = Book.where(city == 'Warsaw')
end

Answer 1

1）查找library_id不为零的记录：

def index
  @books = Book.where.not(library_id: nil)
end

2）查找city为'Warsaw'的记录：

def warsaw_books
  @books = Book.where(city: 'Warsaw')
end