django 'set' object does not support indexing

在定義Model之后使用syncdb 同步的時候報出這個錯誤，檢查之后發現是用錯了。在model的Meta里面，排序這些用的應該是

ordering = ['last','first','middle']
unique_together = ['first','last','middle']
verbose_name_plural = "people"

如果是誤寫成

ordering = {'last','first','middle'}
        unique_together = {'first','last','middle'}
        verbose_name_plural = "people"

會出現 'set' object does not support indexing