Mongodb C# driver ignore Null and Empty Lists (ToBsonDocument)

Question

ConventionRegistry.Register("IgnoreIfDefault", 
                            new ConventionPack { new IgnoreIfDefaultConvention(true) }, 
                            _ => true);

var bsonDocument = anon.ToBsonDocument();

using IgnoreIfDefaultConvention can cause an unintended behavior due to the fact it affects all default values. For instance, values, as listed below, will not be saved:

int = 0
decimal = 0
bool = false

If I want to ignore only null values and Empty Arrays what is the best approach?

Answer 1

I didn't use it my own, but I think the answer is this convention: IgnoreIfNullConvention. Also you may configure a particular convention for a particular field:

BsonClassMap.RegisterClassMap<test>(c => c.MapField(e => e.A).SetIgnoreIfNull(ignoreIfNull: true));

or use this attribute BsonIgnoreIfNullAttribute

UPDATE: If you need more complicated convention, you can always implement a custom one: https://mongodb.github.io/mongo-csharp-driver/2.12/reference/bson/mapping/conventions/