That's what rethinkdb told me

[erizocosmico]

rethinkdb: Whoops, looks like there's a bug in this client library, please report it at https://github.com/christopherhesse/rethinkgo/issues/new: MALFORMED PROTOBUF (expected VAR term to have DATUM of type R_NUM):
type: VAR
args {
  type: JSON
  args {
    type: DATUM
    datum {
      type: R_STR
      r_str: "4"
    }
  }
}

Here's the code that thrown that error:

var response []interface{}
err := r.Db("magnet").
    Table("bookmarks").
    Filter(r.Row.Attr("User").
    Eq(userId)).
        ConcatMap(func(row r.Exp) r.Exp {
            return row.Attr("Tags")
        }).
    Run(dbSession).
    All(&response)