I have a document in a MongoDB collection like so:

{
  _id: new UUID("31daac77-bcbc-4cd5-bb93-382440f46f16"),
  CompanyId: 'XYZ',
  RequestDate: ISODate("2023-01-10T07:52:32.840Z")
}

It corresponds to an object like so:

public class ReportRequest
{
    public ReportRequest(string companyId)
    {
        this.Id = Guid.NewGuid();
        this.CompanyId = companyId;
        this.RequestDate = DateTime.UtcNow;
    }

    [BsonId]
    [BsonElement("_id")]
    [BsonGuidRepresentation(GuidRepresentation.Standard)]
    public Guid Id { get; }

    [BsonElement]
    public string CompanyId { get; }

    [BsonElement]
    [BsonDateTimeOptions(Kind = DateTimeKind.Utc)]
    public DateTime RequestDate { get; }
}

I then try to query for all documents with a particular CompanyId:

public async Task PrintAvailableReportDatesAsync(string companyId)
{
    var filter = Builders<ReportRequest>.Filter.Eq(r => r.CompanyId, companyId);
    var cursor = await _collection.FindAsync(filter);
    var reportRequests = await cursor.ToListAsync();

    foreach (var req in reportRequests)
        Console.WriteLine($"Id: {req.Id.ToString()}, Date: {req.RequestDate}");
}

I would expect to get the following output:

Id: 31daac77-bcbc-4cd5-bb93-382440f46f16, Date: 2023-01-10T07:52:32.840Z

Instead, I get this:

Id: 00000000-0000-0000-0000-000000000000, Date: 0001-01-01T00:00:00

What am I doing wrong?

CodePudding user response：

From what I tested on my local side, those properties' values were assigned within the constructor.

There are 2 approaches to fix it:

Approach 1: Provide the setter to all properties

public class ReportRequest
{
    public ReportRequest(string companyId)
    {
        this.Id = Guid.NewGuid();
        this.CompanyId = companyId;
        this.RequestDate = DateTime.UtcNow;
    }

    [BsonId]
    [BsonGuidRepresentation(GuidRepresentation.Standard)]
    public Guid Id { get; set; }

    public string CompanyId { get; set; }

    [BsonDateTimeOptions(Kind = DateTimeKind.Utc)]
    public DateTime RequestDate { get; set; }
}

Demo

Approach 2: Create a constructor with three parameters

public class ReportRequest
{
    ...

    public ReportRequest(Guid id, string companyId, DateTime requestDate)
    {
        this.Id = id;
        this.CompanyId = companyId;
        this.RequestDate = requestDate;
    }

    ...
}

Demo