File Uploads update to 3.0

[guardrex]

• @attribute [RequestSizeLimitAttribute(52428800)] in the cshtml. https://github.com/aspnet/AspNetCore.Docs/pull/12344/files#r329287769

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Document Details

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• ID: 9a5cfa38-0e6c-4346-dafc-84ea5c513fcf
• Version Independent ID: c6787f0f-3e9a-6efb-0e6e-5ccb957d3f4a
• Content: File uploads in ASP.NET Core
• Content Source: aspnetcore/mvc/models/file-uploads.md
• Product: aspnet-core
• Technology: aspnetcore-mvc
• GitHub Login: @ardalis
• Microsoft Alias: riande

[guardrex]

@Rick-Anderson I'm going to backlog this one due to special circumstances. There are massive updates for the 2.2 version on #12344. We should get those approved+merged first, then update the topic+sample to 3.0. I just took a look, and adding 3.0 updates to that PR would make it even more 😵.

[Rick-Anderson]

I would add the 3.0 updates to this PR when you have time. That's what I did on a couple PR's that languished for months.

[guardrex]

Let's do it after the major updates go in on that PR. That PR is one of the largest topic+sample updates I've ever done ... It's a 👹 B E A S T 👹 ... took me a full week ... and explains why we're having trouble getting it reviewed, too. After all of that goes in, then it will be a snap to get it up to 3.0. What I don't want to do is add the 3.0 updates to that PR. Alternately trying to update the current topic to 3.0 is even more insane ... the current topic+sample is a 🚂💥, and touching it will create major conflicts with the existing PR.

[douglasg14b]

It looks like the current file upload guidance for large files stops functioning as expected in 3.0. IIS grabbs the entire stream and writes it to disk, then hands things off to the controller method. Rather than the stream being accessible in the controller method through the HttpRequest

[FeodorFitsner]

A note: to make large file upload sample work in .NET Core 3.0 RTM DisableFormValueModelBinding source should be changed to:

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
public class DisableFormValueModelBindingAttribute : Attribute, IResourceFilter
{
    public void OnResourceExecuting(ResourceExecutingContext context)
    {
        var factories = context.ValueProviderFactories;
        factories.RemoveType<FormValueProviderFactory>();
        factories.RemoveType<FormFileValueProviderFactory>();
        factories.RemoveType<JQueryFormValueProviderFactory>();
    }

    public void OnResourceExecuted(ResourceExecutedContext context)
    {
    }
}