MongoDb c＃driver 2.0 BsonNull用法

Question

I have isDeleted Nullable property in Profile class.

Builders<Profile>.Filter.Eq(p => p.IsDeleted, BsonNull.Value)

But the following code raised next compilation error:

Error 11    Cannot convert lambda expression to type 
'MongoDB.Driver.FieldDefinition<MongoDB.DataTypes.Profile,MongoDB.Bson.BsonNull>' 
because it is not a delegate type   

How to implement a null-check ?

Answer 1

如果IsDeleted为空，那么在查询时可以使用简单的null而不是BsonNull.Value ：

Builders<Profile>.Filter.Eq(p => p.IsDeleted, null)