C#•3y ago

Query over multiple entities using the same interface [Answered]

I have a EF setup, where ~20 entities implement IArchivable This interface has a public

public Guid Id { get; }
public Guid IsArchived { get; set; }

public Guid Id { get; }
public Guid IsArchived { get; set; }

I wish to perform a query to find the entity with a certain id, and then another query to set the IsArchived property to false. Is this possible with EF? (something like _context.Set<IArchivable>().Where(...) Or should I loop through all types (using reflection) and build an IQueryable for each of them?

7 Replies

ero•3y ago

You can't have full lambda bodies in EF right? Pissed me off last time I worked with it too

Tvde1OP•3y ago

yeah no full lambda bodies, but you can do a whole lot with expressions

ero•3y ago

If you can, you'd do

_context.Set<IArchivable>.FirstAsync(a =>
{
  if (a.Id != yourId)
    return false;

  a.IsArchived = false;
  return true;
});

_context.Set<IArchivable>.FirstAsync(a =>
{
  if (a.Id != yourId)
    return false;

  a.IsArchived = false;
  return true;
});

Don't know if possible with expressions

Tvde1OP•3y ago

let me try if the .Set<Interface> works I think I tried it and it didn't, but I should try again

ero•3y ago

Ah, that part wasn't already correct? Don't know the answer on that one

Tvde1OP•3y ago

I'm going for something like this now

private static IEnumerable<IQueryable<IArchivableEntity>> GetAllArchivableTypes()
{
    var dbProjectTypes = typeof(DataContext).Assembly.GetTypes();
    var setMethodInfo = typeof(DataContext).GetMethod(nameof(DataContext.Set), BindingFlags.Public | BindingFlags.Instance);

    var archivableEntityTypes = dbProjectTypes.Where(x => x.IsAssignableTo(typeof(IArchivableEntity)) && !x.IsInterface);
    
    return archivableEntityTypes.Select(type => {
        var typedMethod = setMethodInfo.MakeGenericMethod(type);
        return typedMethod.Invoke(_context, null) as IQueryable<IArchivableEntity>;
    });
}

private static IEnumerable<IQueryable<IArchivableEntity>> GetAllArchivableTypes()
{
    var dbProjectTypes = typeof(DataContext).Assembly.GetTypes();
    var setMethodInfo = typeof(DataContext).GetMethod(nameof(DataContext.Set), BindingFlags.Public | BindingFlags.Instance);

    var archivableEntityTypes = dbProjectTypes.Where(x => x.IsAssignableTo(typeof(IArchivableEntity)) && !x.IsInterface);
    
    return archivableEntityTypes.Select(type => {
        var typedMethod = setMethodInfo.MakeGenericMethod(type);
        return typedMethod.Invoke(_context, null) as IQueryable<IArchivableEntity>;
    });
}

let's test if it works

Accord•3y ago

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Query over multiple entities using the same interface [Answered]