MongoDB F＃IgnoreExtraElements

Question

I am using the MongoDB.Fsharp Driver and I've got some fields in newer records that I don't have in older records for a given collection.

So when I want to create a query that includes older records, it gives me the following exception: MongoDB.Bson.BsonSerializationException: No matching creator found.

I've googled around and apparently I need to add the below code but it still doesn't work. I've also tried to annotate the type with the BsonIgnoreExtraElements atrribute but that does not work either.

let pack = ConventionPack();
pack.Add(IgnoreExtraElementsConvetion(true))
ConventionRegistry.Register("IgnoreExtraElements", pack, (fun -> _ -> true))

Answer 1

Don't know if this is relevant but should

IgnoreExtraElementsConvetion

be

IgnoreExtraElementsConve**n**tion

?

Answer 2

Also - and this is a total guess, should

(fun -> _ -> true)

be

(fun _ -> true)