Updating an embedded document in MongoDB with official C# driver

Question

If I have a Company collection which contains embedded Divisions:

{ 
  \"_id\": 1 
  \"_t\": \"Company\", 
  \"Name\": \"Test Company\" 
  \"Divisions\": [ 
         


        

Answer 1

You could use the positional array modification feature of MongoDB to update an entire division in the array at once as follows:

var division = GetDivisionById(1);
division.Name = "New Name";
// change any other properties of division you want
collection.Update(
    Query.EQ("Divisions._id", 1),
    Update.Set("Divisions.$", BsonDocumentWrapper.Create<IDivision>(division))
);

The key things going on here are:

1. The use of the "$" in Update.Set
2. Since Update.Set requires a BsonValue as its second argument we have to use a BsonDocumentWrapper to hold the division value (the IDivision type parameter to Create sets the nominalType at serialization to IDivision which results in the "_t" discriminator being written).