params.require(:user).permit(:tag_ids => [])

https://github.com/rails/strong_parameters

The permitted scalar types are String, Symbol, NilClass, Numeric, TrueClass, FalseClass, Date, Time, DateTime, StringIO, IO, ActionDispatch::Http::UploadedFile and Rack::Test::UploadedFile.

To declare that the value in params must be an array of permitted scalar values map the key to an empty array:

params.permit(:id => [])

#2 楼 @Stone 谢谢

下次请帖代码，不要截图

如果 permit 中有多个参数，请把数组参数放在最后面

#4 楼 @huacnlee

select 下拉框为什么也传不过去？