mongodb .net driver V2: How to do array operations -

i'm totally lost on doing crud , other operations on array elements in embedded array in mongodb using c# drivers.

given have following classes (simple example):

public class child {     public objectid id;     public datetime dateofbirth;     public string givenname; }   class family {     public objectid id;     public string name;     public list<child> children; } 

my collection should store family documents.

how i:

1. add new child family
2. delete child
3. update 1 child
4. count children of 1 family
5. get youngest child of family
6. load 1 specific child

without loading whole family object

although i'm taking part in mongo university class mongo.net i'm lost , documentation on working arrays not existing.

i know got answers 1-4:

    //add child     families.updateone(builders<family>.filter.where(x=>x.name=="burkhart"), builders<family>.update.addtoset("children",         new child() {dateofbirth = new datetime(2005, 4, 26), givenname = "finn"}));      // add     families.updateone(builders<family>.filter.where(x => x.name == "burkhart"), builders<family>.update.addtoset("children",         new child() { dateofbirth = new datetime(2007, 4, 26), givenname = "florentina" }));      //remove 1     families.updateone(builders<family>.filter.where(x => x.name == "burkhart"),         builders<family>.update.pullfilter(c => c.children, m => m.givenname == "florentina"));      //update 1     families.updateone(builders<family>.filter.where(x => x.name == "burkhart" && x.children.any(c => c.givenname =="finn")),                         builders<family>.update.set(x=> x.children[-1].givenname,"finn linus"));      //count children     var numberofchildren =         families.aggregate()             .match(f => f.name == "burkhart")             .project(new bsondocument("count", new bsondocument("$size", "$children")))             .firstordefault()             .getvalue("count")             .toint32(); 

as 1-4 fixed - congratulations! please find 5 , 6 discussed in chat.

full code in github repository

        var f = generatefaimly();         collection.insertone(f);          var sort = bsondocument.parse("{\"kids.dateofbirth\": -1}"); // youngest          var project =             bsondocument.parse(                 "{_id:'$children._id', dateofbirth:'$children.dateofbirth', givenname:'$children.givenname', isalive:'$children.isalive'}");         var aggregate = collection.aggregate().match(x => x.id == f.id)              // .project(x => new { kids = x.children })             .unwind("children").sort(sort).limit(1).project<child>(project);          console.writeline(aggregate.tostring());          var result = aggregate.firstordefault();          var pojectionisalive =             bsondocument.parse(                 "{_id:1, name:1, children:{$filter:{ input:'$children', as:'kids', cond:{$eq:['$$kids.isalive', true]}}}}");          var kids = collection.aggregate().match(x => x.id == f.id).project<family>(pojectionisalive).tolist();