Blazor OnInitializedAsync

Question

Is there a fix to OnInitializedAsync being called twice in Blazor server project? I've seen people say get the results from the database and store them in cache so the 2nd call will be from cache. This isn't a fix and is a terrible answer and surely not a solution. Is there a method like OnInitializedAsync that is only called once where we can call our API's to get the data for the screen?

Scott

Answer 1

Hi @ScottDurrett-9763 ,

You could go to _Host.cshtml and change render-mode="ServerPrerendered" to render-mode="Server", and it would be called only once.

Reference:

• https://learn.microsoft.com/en-us/aspnet/core/blazor/components/lifecycle?view=aspnetcore-3.1#stateful-reconnection-after-prerendering
• https://stackoverflow.com/a/58077021/11398810

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Best Regards,

Rena

Answer 2

Hello @ScottDurrett-9763 Thank you for reaching out.
As pointed by @Rena Ni - MSFT , you are most probably using the ServerPrerendered mode.
This is useful when you need to display the page immediately to the user and then make it interactive. Changing it to Server should fix the problem.

If you need a method that is called only once, you can use OnAfterRenderAsync. This is invoked after the component has rendered.

        protected override async Task OnAfterRenderAsync(bool firstRender)  
        {  
            if (firstRender)  
            {  
               await LoadData();  
            }  
        }  

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