If you set a datetime on a datetime property which is indexed by dgraph, the whole dgraph db is crashing as Date / time is serialized, another way as dgraph expect it.
Either serialize the date in the right way (Use binary format for time as expected by go
https://golang.org/src/time/time.go [look for marshall]).
Or send as string in ISO8061 format and regex check every string on query if it's a datetime