Structure for sharing data between users.

[mruncola]

I'm trying to figure out how to approach this problem.

Given two entities. Operating in a READ-ONLY capacity.
Device [UserId, Name]
DeviceShare [UserId, SharedToUserId]

What would be the right mechanism to load all products that I own or am shared.

I use the IAccessControlProvider to return Device[] which is working for the users own data. I'm stumped on how I would generate Device[] return with both owned and shared. Appreciate any guidance here.

[adrianhall]

How would you do it in SQL and EF Core?

Can you create a view within SQL? - Yes, just create an EF Core based image of the view.
If not, can you construct an EF Core IQueryable context with the appropriate search and put it in a new read-only repository implementation

Devil is in the details here, so there is no "one size fits all" type of thing.

[mruncola]

Thank you Adrian, the view was a nice way to accomplish.

For anyone wanting to do something like this in the future.

Added view "DevicesMerged" to db:

SELECT d.*, s.SharedToUserId FROM Device d LEFT JOIN DeviceShare s ON d.Id = s.DeviceId

Set up Entity:

public class DeviceMerged : Device, ISharedToUserId
{
    public string? SharedToUserId { get; set; }
}

Setting up the entity to work via the view:

modelBuilder.Entity\<DeviceMerged\>(entity =>
{
    entity.ToView("DevicesMerged");
});

Created a IAccessControlProvider following this sample:
https://communitytoolkit.github.io/Datasync/in-depth/server/index.html#configure-access-permissions

Modified the class to SharedViewPrivateAccessControlProvider and changed these two methods to add SharedToUserId:

public Expression<Func<T,bool>>? GetDataView()
{
    return (UserId == null)
        ? _ => false
        : model => model.UserId == UserId || model.SharedToUserId == UserId;
}

public ValueTask<bool> IsAuthorizedAsync(TableOperation operation, T? entity, CancellationToken cancellationToken = new CancellationToken())
{
    if (operation == TableOperation.Create || operation == TableOperation.Query)
    {
        return ValueTask.FromResult(true);
    }
    return ValueTask.FromResult(
        (entity?.UserId != null && entity?.UserId == UserId) ||
        (entity?.SharedToUserId != null && entity?.SharedToUserId == UserId)
        );
}

[adrianhall]

Probably worth a blog post or something - nice code!