Select item for first list<T> by comparing with another list<Y> using linq or lambda expression

Question

In the below code, the result returns list of bool, whereas I am expecting it to be List of BState. This should satisfy the condition mentioned in the query.

How this can be achieved. Please can someone help here?

public class Client
{
public void Execute()
{
    var response = new DataResponse();

    var BStates = new List<BState>();
    var BState = new BState() { BId = 106, CurBState = new BState() { TerminalId = 0 } };
    BStates.Add(BState);
    BState = new BState() { BId = 107, CurBState = new BState() { TerminalId = 0 } };
    BStates.Add(BState);
    BState = new BState() { BId = 108, CurBState = new BState() { TerminalId = 0 } };
    BStates.Add(BState);
    BState = new BState() { BId = 109, CurBState = new BState() { TerminalId = 0 } };
    BStates.Add(BState);
    BState = new BState() { BId = 110, CurBState = new BState() { TerminalId = 0 } };
    BStates.Add(BState);
    
    response.CurBStates = BStates;
    
    var UResources = new List<UResource>();
    var UResource = new UResource() { Name = "U1", Type = RType.A, UReason = UReason.Unknown };
    UResources.Add(UResource);
    UResource = new UResource() { Name = "U2", Type = RType.A, UReason = UReason.Unknown };
    UResources.Add(UResource);
    UResource = new UResource() { Name = "101", Type = RType.B, UReason = UReason.Unknown };
    UResources.Add(UResource);
    UResource = new UResource() { Name = "102", Type = RType.B, UReason = UReason.BCM };
    UResources.Add(UResource);
    getBotAssignmentSnapshotResponse.UResources = UResources;



    var Result = response.CurBStates
                         .Select(c => response.UResources
                         .Any(u => u.Name != c.BotId.ToString()&& 
                                   c.CurBState.TerminalId == 0 &&
                                   u.Type == RType.B &&
                                   u.UReason != UReason.BCM));
                                   
}
}

Answer 1

It seems that you need SelectMany (Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence.) + Where combination (Any, as you can see returns bool):

var Result = response.CurBStates
    .SelectMany(c => response.UResources
        .Where(u => u.Name != c.BotId.ToString()&& 
                  c.CurBState.TerminalId == 0 &&
                  u.Type == RType.B &&
                  u.UReason != UReason.BCM));

P.S.

Use collection initializers instead of "manually" calling Add:

var BStates = new List<BState>
{
    new BState() { BId = 106, CurBState = new BState() { TerminalId = 0 } },
    new BState() { BId = 107, CurBState = new BState() { TerminalId = 0 } },
    // ...
};

UPD

To get results exactly matching the foreach in the comments you ca do:

var Result = response.CurBStates
    .SelectMany(c => response.UResources
        .Where(u => u.Name != c.BotId.ToString() &&
                    c.CurBState.TerminalId == 0 &&
                    u.Type == RType.B &&
                    u.UReason != UReason.BCM)
        .Select(_ => c));;

If you don't need potential duplicates in the result then you need Where instead of Select in the original query:

var Result = response.CurBStates
    .Where(c => response.UResources
        .Any(u => u.Name != c.BotId.ToString() &&
                    c.CurBState.TerminalId == 0 &&
                    u.Type == RType.B &&
                    u.UReason != UReason.BCM));