How can i access related data and convert foreign keys into objects for displaying their properties - asp.net

Question

I have
class User {
...
...
ICollection<Transaction> transactionsUserMade;
}
and
class Transaction {
int ID;
int userThatSentMoneyID;
int userToWhomHeSentMoneyID;
}
I'm trying to make profile page where user can see all transactions he made and to whom. I managed to relate users and transaction but I'm getting integer values, as i should by using
await _context.Users
.Include(u => u.transactionsUserMade)
.AsNoTracking()
.FirstOrDefaultAsync(u => u.ID == userId);
How can i turn those ID's to actual objects of Users so i could get their usernames and display them on Razor Page.

Answer 1

Found one solution. I tweaked Transaction class by adding User userThatRecievedMoney property. And after getting transactions from specific user i manually set that property.
foreach(var transaction in _user.transactionsUserMade)
{
transaction.userThatRecievedMoney = _context.Users
.Where(u => u.ID == transaction.userToWhomHeSentMoneyID).FirstOrDefault();
}

Answer 2

You can use Navigation Property to help you with that as long as you can modify those entity models User and Transaction.
public class UserEntity
{
public int Id { get; set; }
public string Name { get; set; }
public string Email { get; set; }
public List<TransactionEntity> TransactionsAsSender { get; set; }
public List<TransactionEntity> TransactionsAsRecipient { get; set; }
}
public class TransactionEntity
{
public int Id { get; set; }
public double Amount { get; set; }
public string Note { get; set; }
// Foreign key to UserEntity
public int SenderId { get; set; }
public UserEntity Sender { get; set; }
// Foreign key to UserEntity
public int RecipientId { get; set; }
public UserEntity Recipient { get; set; }
}
Then you need to setup their relationships.
public class AppDbContext : DbContext
{
public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) {}
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Entity<UserEntity>(b => {
b.HasKey(x => x.Id);
b.Property(x => x.Name).IsRequired();
b.Property(x => x.Email).IsRequired();
b.ToTable("User");
});
builder.Entity<TransactionEntity>(b => {
b.HasKey(x => x.Id);
b.Property(x => x.Amount).IsRequired();
// Configure relationships
b.HasOne(x => x.Sender)
.WithMany(u => u.TransactionsAsSender)
.HasForeignKey(x => x.SenderId);
b.HasOne(x => x.Recipient)
.WithMany(u => u.TransactionsAsRecipient)
.HasForeignKey(x => x.RecipientId);
b.ToTable("Transaction");
});
}
public DbSet<UserEntity> Users { get; set; }
public DbSet<TransactionEntity> Transactions { get; set; }
}
After their relationships are setup, you can easily query the related data via navigation properties.
For example, let's say you have view model called UserProfileViewModel and UserProfileTransactionViewModel to contain the information it needs for display purpose.
public class UserProfileViewModel
{
public int UserId { get; set; }
public string UserName { get; set; }
public string UserEmail { get; set; }
public IEnumerable<UserProfileTransactionViewModel> TransactionsAsSender { get; set; }
public IEnumerable<UserProfileTransactionViewModel> TransactionsAsRecipient { get; set }
}
public class UserProfileTransactionViewModel
{
public int TransactionId { get; set; }
public string Sender { get; set; }
public string Recipient { get; set; }
public string Amount { get; set; }
}
In the controller,
var user = _dbContext.Users
.AsNoTracking()
.Include(x => x.TransactionsAsSender)
.Include(x => x.TransactionsAsRecipient)
.SingleOrDefault(x => x.Id == userId);
if (user == null)
{
return NotFound();
}
var vm = new UserProfileViewModel
{
UserId = user.Id,
UserName = user.Name,
UserEmail = user.Email,
TransactionsAsSender = user.TransactionsAsSender
.Select(x => new UserProfileTransactionViewModel
{
TransactionId = x.Id,
Sender = x.Sender.Name,
Recipient = x.Recipient.Name,
Amount = x.Amount.ToString("c")
}),
TransactionsAsRecipient = user.TransactionsAsRecipient
.Select(x => new UserProfileTransactionViewModel
{
TransactionId = x.Id,
Sender = x.Sender.Name,
Recipient = x.Recipient.Name,
Amount = x.Amount.ToString("c")
})
};
return View(vm);
You could even have just a list of all transactions off UserProfileViewModel. You can combine TransactionsAsSender and TransactionsAsRecipient from UserEntity to fill the list.
Disclaim:
I wrote everything by hand and with my imagination :p