Blazor concurrency problem using Entity Framework Core

Question

My goal

I want to create a new IdentityUser and show all the users already created through the same Blazor page. This page has:

1. a form

Answer 1

I found your question looking for answers about the same error message you had.

My concurrency issue appears to have been due to a change that triggered a re-rendering of the visual tree to occur at the same time as (or due to the fact that) I was trying to call DbContext.SaveChangesAsync().

I solved this by overriding my component's ShouldRender() method like this:

    protected override bool ShouldRender()
    {
        if (_updatingDb)
        { 
            return false; 
        }
        else
        {
            return base.ShouldRender();
        }
    }

I then wrapped my SaveChangesAsync() call in code that set a private bool field _updatingDb appropriately:

        try
        {
            _updatingDb = true;
            await DbContext.SaveChangesAsync();
        }
        finally
        {
            _updatingDb = false;
            StateHasChanged();
        }

The call to StateHasChanged() may or may not be necessary, but I've included it just in case.

This fixed my issue, which was related to selectively rendering a bound input tag or just text depending on if the data field was being edited. Other readers may find that their concurrency issue is also related to something triggering a re-render. If so, this technique may be helpful.