Upserting in Mongo DB using official C# driver

Question

In the official documentation of mongodb they mention upserts, so it would be really nice to write an upsert command instead of:

if (_campaignRepo.Exists(camp))
{
    _campaignRepo.DeleteByIdAndSystemId(camp);
}

_campaignRepo.Save(camp);

something which would implement that logic on the db level if it is possible. So what is the way to do an upsert if there is one?

Answer 1

Version 2 of the MongoDB C# driver requires setting the IsUpsert flag in the write commands. This example will upsert an entire document.

var newDoc = new BsonDocument { { "_id", 123 }, { "someKey", "someValue" } };
var result = await collection.ReplaceOneAsync(
                filter: new BsonDocument("_id", 123),
                options: new ReplaceOptions { IsUpsert = true },
                replacement: newDoc);

Version 1 of the MongoDB C# driver implements this logic within the Save command.

var newDoc = new BsonDocument { { "_id", 123 }, { "someKey", "someValue" } };
collection.Save(newDoc);

The Save method is a combination of Insert and Update. If the Id member of the document has a value, then it is assumed to be an existing document and Save calls Update on the document (setting the Upsert flag just in case it actually is a new document after all). Otherwise it is assumed to be a new document and Save calls Insert after first assigning a newly generated unique value to the Id member.

Reference: http://mongodb.github.io/mongo-csharp-driver/1.11/driver/#save-tdocument-method

Note: This does require the proper mapping of the Id field however. More info on that here: http://mongodb.github.io/mongo-csharp-driver/1.11/serialization/#identifying-the-id-field-or-property