How to wait for Async Foreach before updating records

Question

I have the block of code below where I update a list of users in an async foreach block. Then I have to parse that list of users to another service. The problem is even if I set the users value isRegistered to true, when it gets to the _secondService.UpdateUsers function, the value is still false.

The secondService function has to be outside the foreach. I understand it has something to do with the async, but I have also awaited the second service. Is there a workaround for this?

        userList.ForEach(async user =>
        {
            if (user.isRegistered == false)
            {
                if (await _service.RegisterUser(user))
                {
                    user.isRegistered = true;
                }
            }
        });

        await _secondService.UpdateUsers(userList);

Don't use `List.Foreach`, use `await foreach` instead. On the other hand, if you use EF Core or a similar ORM, inserting users one by one is a smell - a DbContext tracks all changes and persists *all* of them in a batch when `SaveChanges` is called. You could pass `userList` to that service, have it do its job and then proceed. Batch operations are a lot faster than individual ones too. A single INSERT with 100 rows is more than 100 times faster than 100 individual inserts. It's faster than a batch of 100 INSERTs too — Panagiotis Kanavos, Oct 26 '22 at 06:57

score 0 · Answer 1 · answered Oct 26 '22 at 07:27

0

Yes @panagiotis answer is right. I changed to the below and it worked:

foreach(var user in userList){
 // do stuffs inside
}

answered Oct 26 '22 at 07:27

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How to wait for Async Foreach before updating records

1 Answers1