Question

My Sum and Max calls on last used and usage count are wrong. They are always the value that is stored in the second maps value which is currently set to 0. I can make it -100 and that is what the reduce result will be. I noticed someone saying that you should make it an array but I don’t understand how that helps. I have a linq expression over objects using the map/reduce that works properly assuming that the two maps are unioned together.

Here’s the data => https://gist.github.com/940ccca1b0f8917e9eaf

I want to support a query like

        var stats = Session.Query<MultiMapApiKeyStats.ApiKeyStats, MultiMapApiKeyStats>()
            .Customize(x => x.WaitForNonStaleResultsAsOfNow())
            .Where(x => x.AccountId == Account.Id)
            .OrderBy(x => x.Key).ToList();

and build a table like

 public MultiMapApiKeyStats()
        {
            AddMap<KeyUsageBase>(uses => from use in uses
                                         select new
                                         {
                                             AccountId = use.AccountId,
                                             ApiKeyId = use.ApiKeyId,
                                             Key = (string)null,
                                             UsageCount = 1,
                                             LastUsed = use.LastUsedTicks,
                                             Pattern = (string)null,
                                             Status = ApiKey.KeyStatus.None,
                                             Type = ApiKey.ApplicationType.None
                                         });
            AddMap<ApiKey>(keys => from key in keys
                                   select new
                                          {
                                              AccountId = key.AccountId,
                                              ApiKeyId = key.Id,
                                              Key = key.Key,
                                              UsageCount = 0,
                                              LastUsed = 0,
                                              Pattern = key.Pattern,
                                              Status = key.ApiKeyStatus,
                                              Type = key.Type
                                          });


            Reduce = results => from result in results
                                group result by result.ApiKeyId
                                    into g
                                    select new
                                           {
                                           AccountId = g.Select(x => x.AccountId).FirstOrDefault(),
                                           ApiKeyId = g.Key,
                                           Key = g.Select(x => x.Key).FirstOrDefault(x => x != null),
                                           UsageCount = g.Sum(x => x.UsageCount),
                                           LastUsed = g.Max(x => x.LastUsed),
                                           Pattern = g.Select(x => x.Pattern).FirstOrDefault(),
                                           Status = g.Select(x => x.Status).FirstOrDefault(),
                                           Type = g.Select(x => x.Type).FirstOrDefault()
                                           };

Answer 1

The indexing error sequence contains no matching elements is a result of invoking First on an empty collection which is why you should use FirstOrDefault. Also, referencing your own classes in map and reduce declarations will cause errors because RavenDB can’t resolve those types at indexing time.