Sort By Foreign Key or Custom Column in Symfony Admin Generator use propel

Sort By Foreign Key or Custom Column in Symfony Admin Generator use propel。在admin list页面自定义的列，如何能让他也能有排序功能。

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自己找到方法了，分享一下。
Sorting On A Virtual Column
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The new theme provides an easy way to make virtual columns and foreign key columns sortable in the list view. Just declare the corresponding fields with is_sortable to true, and the generated module will look for an orderByXXX() method in the generated query. For instance, to allow a book list to be sortable on the author name:

Then the generator will try to execute BookQuery::orderByAuthor() whenever the user clicks on the Author header to sort on this column. The method must be implemented as follows:

You can override the default sorting method name for a field by setting the sort_method parameter: