How to extend the class to add a property UserId?

Question

I am using Signalr and there is a class:

public class Device:Hub<T>
{

}

I want to add a property UserId in the class. so I want to ask how to add a property to the class Hub so I can use it?

Answer 1

Hi @mc ,

You can get the user id via the following code:

var userId = Context.UserIdentifier;

Or find the user via DbContext and the username, code like this:

    var user = _dbContext.Users.Where(c => c.UserName == username).FirstOrDefault();  
    if(user != null)  
    {  
        var id = user.Id;  
    }  

The detail sample code as below: (In my sample, the user id is a Guid value, and it is auto generated when insert new user)

[Authorize]  
public class MyChatHub : Hub  
{  
    private static Dictionary<string, List<string>> NtoIdMappingTable = new Dictionary<string, List<string>>();  
    private readonly ApplicationDbContext _dbContext;  
    public MyChatHub(ApplicationDbContext applicationDbContext)  
    {  
        _dbContext = applicationDbContext;  
    }  
    public override async Task OnConnectedAsync()  
    {  
        var username = Context.User.Identity.Name;  
        var userId = Context.UserIdentifier;  

        var user = _dbContext.Users.Where(c => c.UserName == username).FirstOrDefault();  
        if(user != null)  
        {  
            var id = user.Id;  
        }  

        List<string> userIds;  

        //store the userid to the list.  
        if (!NtoIdMappingTable.TryGetValue(username, out userIds))  
        {  
            userIds = new List<string>();  
            userIds.Add(userId);  

            NtoIdMappingTable.Add(username, userIds);  
        }  
        else  
        {  
            userIds.Add(userId);  
        }  

        await base.OnConnectedAsync();   
    }  

The debug screenshot:

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Best regards,
Dillion