使用index：true命名迁移中的索引

I have a migrate, below, where I create an index with index: true. However, the name is too long for that index so I attempted to name it myself. However, that doesn't seem to run. I get the same "name too long" error. Is there a way to name an index like this with index: true? If not, how do I go about naming it with add_index?I have a migrate, below, where I create an inde