使用基于搜索的C#驱动获取MongoDB集合的子集合

Question

I have this project with https://github.com/Mech0z/Foosball/blob/master/Models/Old/PlayerRankHistory.cs

I have the following classes where PlayerRankHistory is saved in MongoDB, this contains a list of PlayerRankHistorySeasonEntry which each contains PlayerRankHistoryPlot.

I would then like to provide an email of a player and a seasonname and then only get the list PlayerRankHistoryPlots out as a list, but the code I have written is very slow and not faster than just providing only an email and getting much more data out

And as a side note, not sure how to write it to make it async

The query I have now is

public async Task<List<PlayerRankHistoryPlot>> GetPlayerRankEntries(string email, string seasonName)
{
    var query = Collection.AsQueryable().SingleOrDefault(x => x.Email == email)
        .PlayerRankHistorySeasonEntries.SingleOrDefault(x => x.SeasonName == seasonName).HistoryPlots;
    List<PlayerRankHistoryPlot> result = query.ToList();
    return result;
}


public class PlayerRankHistory
{
    public PlayerRankHistory(string email)
    {
        Email = email;
        PlayerRankHistorySeasonEntries = new List<PlayerRankHistorySeasonEntry>();
    }

    public Guid Id { get; set; }
    public string Email { get; set; }
    public List<PlayerRankHistorySeasonEntry> PlayerRankHistorySeasonEntries { get; set; }
}

public class PlayerRankHistorySeasonEntry
{
    public PlayerRankHistorySeasonEntry(string seasonName)
    {
        SeasonName = seasonName;
        HistoryPlots = new List<PlayerRankHistoryPlot>();
    }

    public string SeasonName { get; set; }
    public List<PlayerRankHistoryPlot> HistoryPlots { get; set; }
}

public class PlayerRankHistoryPlot
{
    public PlayerRankHistoryPlot(DateTime date, int rank, int eloRating)
    {
        Date = date;
        Rank = rank;
        EloRating = eloRating;
    }

    public DateTime Date { get; set; }
    public int Rank { get; set; }
    public int EloRating { get; set; }
}

An example of a document

{"_id":"AYU3e3Qgw0Gut1fngze80g==","Email":"someemail@gmail.com","PlayerRankHistorySeasonEntries":[{"SeasonName":"Season 1","HistoryPlots":[{"Date":"2020-01-10T12:24:12.511Z","Rank":11,"EloRating":1488},{"Date":"2020-01-13T12:51:41.597Z","Rank":12,"EloRating":1488},{"Date":"2020-01-15T11:11:43.223Z","Rank":10,"EloRating":1510},{"Date":"2020-01-15T11:11:45.049Z","Rank":8,"EloRating":1530},{"Date":"2020-01-15T12:14:58.042Z","Rank":9,"EloRating":1530},{"Date":"2020-01-15T12:14:59.886Z","Rank":8,"EloRating":1530}]}]}

Answer 1

I believe when you define Collection.AsQueryable().FirstOrDefault() , you are pulling all records in that collection and then filtering through them. You should use the Find() method that is provided by MongoDB C# driver to filter the records which is much faster as well.

1. Get the PlayerRankHistory objects based on the email address
2. From on the filtered records, only return the records that have the required season
3. Get the HostoryPlots for only the first match as list

Collection.Find(Builders<PlayerRankHistory>.Filter.Eq(x => x.Email, email))
            .Select(y => y.PlayerRankHistorySeasonEntries.Where(z => z.SeasonName.Equals(seasonName)))
            .FirstOrDefault()?.HistoryPlots
            .ToList();