MongoDB Update Query with Multiple entries

Question

I am trying to get an output like this:

> "expires" : {
>                 "date" : 30,
>                 "year" : 2017,
>                 "month" : 6
>         },

My Code looks like this:

..update({ID:1},($set: {expires: {year: 2017, month : 6, date: 30}}))

I am not getting the desired output. What am I doing wrong?