处理多选不带选择 [英] handling multi-select with no selection

问题描述

我在我的应用程序中使用了 grails generate-all 。 作者视图有一个允许多个 Book 实例的多重选择：

I used grails generate-all on my application. The Author view has a multi-select which allows for a number of Book instances:

<g:select multiple="true" ... />

但是，如果我编辑现有的作者谁拥有15本书中的5本（多选显示15本书，5选），取消选择所有书籍并点击保存，作者仍然保留他们的5本书。从我所知道的情况来看， Author 的form - books属性没有任何书籍输入不会被更改。

However, if I edit an existing Author who owns 5 out of total 15 books (the multi-select shows 15 books, 5 selected), unselect all books and click save, the Author still keeps their 5 books. From what I can tell, no book input from the form - books property of Author don't get changed.

现在，我可以在我的控制器中进行测试（如下所示）：

Now, I can test for this in my controller (something like this):

if (params?.books.size() < 1) {
     authorInstance.books = []
}

是这样做的，或者有更好的方法吗？

Is this the way to do it, or is there a better way?

推荐答案

我见过的大多数示例都使用：

Most examples I've seen use:

authorInstance.books.clear()

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