Patch REST API to Partial Update MongoDB in .NET

Question

I have an object

{
  \"_id\": \"testobject\",
  \"A\": \"First line\",
  \"B\": \"Second line\",
  \"C\": \"Third line\"
}

I want to send a RE

Answer 1

I suggest that you avoid relying on 1.x legacy API, as it's perfectly supported in 2.x as well, as shown in the sample code below.

var client = new MongoClient();
var database = client.GetDatabase("test");
var collection = database.GetCollection("test");

var changesJson = "{ a : 1, b : 2 }";
var changesDocument = BsonDocument.Parse(changesJson);

var filter = Builders.Filter.Eq("_id", 1);

UpdateDefinition update = null;
foreach (var change in changesDocument)
{
    if (update == null)
    {
        var builder = Builders.Update;
        update = builder.Set(change.Name, change.Value);
    }
    else
    {
        update = update.Set(change.Name, change.Value);
    }
}

//following 3 lines are for debugging purposes only
//var registry = BsonSerializer.SerializerRegistry;
//var serializer = registry.GetSerializer();
//var rendered = update.Render(serializer, registry).ToJson();

//you can also use the simpler form below if you're OK with bypassing the UpdateDefinitionBuilder (and trust the JSON string to be fully correct)
update = new BsonDocumentUpdateDefinition(new BsonDocument("$set", changesDocument));

var result = collection.UpdateOne(filter, update);

Credits go to Robert Stam for providing the code sample.