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How to remove list object from an item in List?

I have a class:
public class FlightDetails
{
public string FlightId {get; set;}
public string PilotName {get; set;}
public string Area {get; set;}
public string Country {get; set;}
}
Here sending response:
public async Task<List<FlightDetails>> GetFlightAsync(string FlightId)
{
//
var flights = new List<FlightDetails>();
flights = response.AllFlights;
flights = flights.Where(x => x.FlightId.Contains(FlightId)).ToList();
//
return flights;
}
Getting List here and data is filled but issue is don't want FlightId and Country in the response which I am sending. How to remove this objects in the List? Finally in the List item there should be only PilotName and Area.
Update:
I forgot the following line before the flights = response.AllFlights;
var request = await _rest.Get<WorldFlights>(url + $"?FlightId={FlightId}");

You will need to create another object, and map there only the properties you want. For example:
public class FlightDetailsResponse
{
public string PilotName {get; set;}
public string Area {get; set;}
}
And then in the function:
public async Task<List<FlightDetailsResponse>> GetFlightAsync(string FlightId){
var flights = response.AllFlights;
var flightResponses = flights
.Where(x => x.FlightId.Contains(FlightId).ToList())
.Select(x => new FlightDetailsResponse{
PilotName = x.PilotName,
Area = x.Area
});
return flightResponses;
}
This way the response will only contain the PilotName and Area fields.
PD: What I wrote might not compile because of missing commas or something like that. Sorry, it has been some time since I last wrote C#, but the idea is that.

How to update a property of an complexObj. inside a Document inside a List<complexObj>? MongoDB C# net.Driver

how to update one property of a document in MongoDb with C# net.Driver.
My data model in C# looks like this:
public class MyMediListsWrapper
{
[BsonId]
public Guid Id { get; set; }
public DateTime Datum { get; set; }
public bool IsActiv { get; set; }
public List<Medi> MediLsts { get; set; }
}
public class Medi
{
public Guid Id { get; set; }
public string Name { get; set; }
public string Typ { get; set; }
public string Vmax { get; set; }
}
Now I want to update only one property of one Obj. (Vmax='Test') of the nested List MediLsts.
I wand to filter the collection MyMediListsWrapper by SingleOrDefault IsActiv=true and then I want to filter 'in this Document' the Medi-Obj. from the nested List inside by Guid='XcPwoEaB8Ey7XR1AEB+fLQ=='
and then update Vmax='Test'.
I have a little bit of code, but it doesn't achieve what I want. I have trouble to do the filter first for IsActiv and then filter inside of that Document again for a different property. And I don't know how to write the code for the update later (if found). Thx for help.
My Code:
var db = client.GetDatabase(MySecret.MyMongoDbName);
var myMediListsWrapper = db.GetCollection<MyMediListsWrapper>(MySecret.MyWrapperColName);
var filter = Builders<MyMediListsWrapper>.Filter;
var filterColAndFilterLstObj = filter.And(
filter.Eq(x => x.IsActiv, true),
filter.ElemMatch(x => x.MediLsts, lst => lst.Id == mySearchGuid));
//Just a Test -- I want to UPDATE a property NOT find a entry
//and this is WRONG because it give me a obj of the outer class not the Medi-Obj.
var result = await myMediListsWrapper.Find(filterColAndFilterLstObj).SingleOrDefaultAsync(); ```

the following update command should do the trick:
await collection.UpdateOneAsync(
filter: w => w.IsActiv && w.MediLsts.Any(m => m.Id == mySearchGuid),
update: Builders<MyMediListsWrapper>.Update.Set(m => m.MediLsts[-1].Vmax, "TEST"));
the thing to note here is the [-1] array/list index above.
the driver translates that to the following $set operation:
$set: { "MediLsts.$.Vmax" : "TEST" }
-1 index position is something special the mongo driver uses to denominate $ which is the first positional operator.
i.e. update the first array element that qualifies for the $elemMatch condition of the filter.
.MediLsts.Any(...) is the LINQ equivalent of filter.ElemMatch(...)

C# driver 2.0 Mongodb UpdateOneAsync

public class Student
{
public long StudentId {get; set;}
public string Fname {get; set;}
public string Lname {get; set;}
public List<ObjectId> CoursesList {get; set;}
public int IQ {get;set;}
}
public class Courses
{
[BsonId]
public ObjectId Id { get; set; }
public string CourseNumber{get; set;}
public string CourseName{get; set;}
}
How do I add/append a courser Id to Course list(which may be null for the first time) of a Student object
PS: I know how to set a field using the below command. I am hoping it is on similar lines for the above problem
await StudentCollection.UpdateOneAsync(a => a.StudentId == studentId, Builders<Student>.Update.Set( a => a.IQ,90));

As you've already discovered, the C# code to use $addToSet is:
var filter = Builders<Student>.Filter.Eq(s => s.StudentId, studentId);
var update = Builders<Student>.Update.AddToSet(s => s.CoursesList, courseId);
var result = await collection.UpdateOneAsync(filter, update);
However, $addToSet is not going to work if the CourseList member has been stored in the collection as a null. The server requires that the existing value for $addToSet be an array (it can be an empty array).
The easiest solution is to just store an empty list for CoursesList instead of a null when there are no courses.

This is working for me. When you define "List" like this, it will be empty and works with AddToSet/Push methods.
public List<ObjectId> CoursesList = new List<ObjectId>();

The only case that you have to pay attention is when the array CourseList is null, in this case you have to use the code below (see also here):
var newListOfObject = new List<ObjectId>(){...}
await StudentCollection.UpdateOneAsync(a => a.StudentId == studentId, Builders<Student>.Update.Set( a => a.CoursesList, newListOfObject));
Otherwise you can use AddToSet or Push like explain in the other answers.

Filter Sub-Collection of Collection

I have the following classes:
class Customer
{
public int IdCustomer {get; set}
public string Name {get; set;}
public virtual ICollection<Expertise> Expertises {get; set;}
}
class Expertise
{
public int IdExpertise {get; set;}
public string Description {get; set;}
public virtual ICollection<SubExpertise> SubExpertises {get; set;}
}
class SubExpertise
{
public int IdSubExpertise { get; set;}
public int IdExpertise {get; set;}
public string Description {get; set;}
public virtual Expertise Expertise {get; set;}
}
How I can filter a SubExpertise using a IQueryable, and keep the filter condition? Basically I want to filter by SubExpertise, but keeping the possibilty to add more filters in the query
Example: I wanna all customers that have a SubExpertise 'x' or 'y'. Keep in mind that SubExpertise is a sub-collection of a collection (Expertise). And that I can have new filters after this.

I think you're after a method to build the expressions dynamically. You could use a predicate builder to do the job. My favorite is this one.
Using this little gem you can do this:
var pred = PredicateBuilder.Create<SubExpertise>(s => s.Description == "x");
pred = pred.Or(s => s.Description == "y");
var customers = db.Customers
.Where(c => c.Expertises
.Any(e => e.SubExpertises.AsQueryable()
.Any(pred)));
e.SubExpertises must be cast to IQueryable because it's compile-time type is ICollection, and the extension method Any that fits ICollection doesn't accept an Expression but a Func, so it doesn't compile.

I use a pattern like this for resuable filters, defining the filters as Expressions
public static class SubExpertiseFilter
{
public static Expression<SubExpertise, bool> XorY =
se => se.Description == "X" || se.Description == "Y";
}
Then if I want to apply it:
public IQueryable<Expertise> ApplyXorYFilter(IQueryable<Expertise> expertises, bool appyXorY)
{
if(applyXorY)
{
expertises = expertises.Any(e => e.Subexpertises.AsQueryable().Any(SubExpertiseFilter.XorY);
}
return expertises;
}
Or just do it inline where you need it.
The "AsQueryable" is needed to use the expression inside another expression so that EF is happy with it, otherwise the compiler expects a function there and that isn't something EF can turn into SQL.

Suppose you have a list customers
var filteredCustomers = from customer in customers
where customer.Expertises.Any(e => e.Subexpertises.Any(s => IsXOrY(s)))
select customer;
You can add any filter conditions in IsXOrY: (and you should rename it)
bool IsXOrY(SubExpertise subExpertise)
{
check if the SubExpertise is 'x' or 'y'
check if the SubExpertise meets other criteria
return true if this SubExpertise meets all your criteria
}

Convert cypher query to c#

I have two tables:
User
Name
Surname
Phone
number
type_of_number
var myList = ((IRawGraphClient) client).ExecuteGetCypherResults<**i_need_class_to_save_it**>(
new CypherQuery("match (a:User)-[r]->(b:Phone) return a,collect(b)", null, CypherResultMode.Set))
.Select(un => un.Data);
How create correct collection to save data?

It sounds like you haven't read https://github.com/Readify/Neo4jClient/wiki/cypher or https://github.com/Readify/Neo4jClient/wiki/cypher-examples. You really should start there. It helps to read the manual. I don't just write it for fun.
For your specific scenario, let's start with your Cypher query:
MATCH (a:User)-[r]->(b:Phone)
RETURN a, collect(b)
Now, we convert that to fluent Cypher:
var results = client.Cypher
.Match("(a:User)-[r]->(b:Phone)")
.Return((a, b) => new {
User = a.As<User>(),
Phones = b.CollectAs<Phone>()
})
.Results;
You can then use this rather easily:
foreach (var result in results)
Console.WriteLine("{0} has {1} phone numbers", result.User.Name, result.Phones.Count());
You will need classes like these, that match your node property model:
public class User
{
public string Name { get; set; }
public string Surname { get; set; }
}
public class Phone
{
public string number { get; set; }
public string type_of_number { get; set; }
}
Again, please go and read https://github.com/Readify/Neo4jClient/wiki/cypher and https://github.com/Readify/Neo4jClient/wiki/cypher-examples.

Add a .ToList() at the end of your command?
Like this :
var myList = ((IRawGraphClient) client).ExecuteGetCypherResults<**i_need_Collection**>(
new CypherQuery("match (a:User)-[r]->(b:Phone) return a,collect(b)", null, CypherResultMode.Set))
.Select(un => un.Data).ToList();