MongoDB C＃可空日期时间查询

Question

I'm trying to query a over mongoDB and I get the following error:

Unable to determine the serialization information for the expression: c.IndexMetadata.Indexed. HasValue .

where Indexed is a nullable datetime

my query is the following:

Collection.AsQueryable<Candidate>(c => !c.IndexMetadata.Indexed.HasValue || c.IndexMetadata.Updated.Value > c.IndexMetadata.Indexed.Value).ToList();

both indexed and updated are type of nullable datetime

I guess that's because there's no direct translation from HasValue into a mongo Query, any workaround?

Answer 1

You can compare the DateTime? to null instead of using HasValue :

Collection.AsQueryable<Candidate>(
    c => 
        c.IndexMetadata.Indexed == null || 
        c.IndexMetadata.Updated.Value > c.IndexMetadata.Indexed.Value).
    ToList();