How to use SystemWebAdapter SessionClient to share only registered keys and ignore the others

Rob de Bruin 5

I am learning how to migrate a large .net framework application to .net core and am happy with the tooling provided by SystemWebAdapters and RemoteAppClient. The framework application uses session state extensively and it looks like the default behaviour requires me to register ALL session state keys in advance to avoid getting an exception about unregistered keys. This imposes a threat as the frame work application is large and still actively maintained. Is it possible to configure the SessionClient / Session Serializer (i am using AddJsonSessionSerializer) in such a way what only the registered keys are shared and all others are ignored? (So my application will not break if a developer adds a new key without registering)

Tiny Wang-MSFT 2,731 Reputation points Microsoft Vendor

2024-05-17T02:29:11.31+00:00

Hi @Rob de Bruin , could you please help check this blog to see whether it helped you or not? It has a section introducing Custom session key serializers.
Kyle Fuller 5 Reputation points

2024-06-03T16:11:03.4266667+00:00

Did you have any luck here? The article doesn't discuss ignoring specific keys completely, just how to add a custom serializer which wouldn't solve the issue of missing or ignored keys I don't think?
Kyle Fuller 5 Reputation points

2024-06-03T17:12:38.72+00:00

I did find out that you can ignore missing keys using this:

This will prevent it throwing an exception but missing values will be nulled out so it doesn't really help for my use-case. I did create a support ticket to see if this is a bug or intentional, you can follow that here:
https://github.com/dotnet/systemweb-adapters/issues/503
Rob de Bruin 5 Reputation points

2024-06-06T08:15:28.9+00:00
Thank you very much for your help. I tried Kyle's solution first, and it worked (so far). So I will delay writing my own serializer for now. I might do that anyway in the future because we also have some key's that are determined by data and, thus, cannot be hard coded. I am no thing of a registration that will say handle keys starting with ... like this: .. .

Just to be clear: I needed Kyles snippet and the AddJsonSessionSerializer. Like this:
builder.Services.AddSystemWebAdapters()

.AddSessionSerializer(options => { options.ThrowOnUnknownSessionKey = false; }) .AddJsonSessionSerializer(options => { options.RegisterKey<string>("AppVersion"); })
Kyle Fuller 5 Reputation points

2024-06-06T14:49:16.5+00:00

A couple of notes.

I want to stress that if you don't map a key, then when you go from the Framework site to the Core/.NET site and back, the value will be null in session. So if you have like a cart object in session on the framework side and dont map the key and you land on a fully converted page on the Core/.NET side, that cart will be nulled out. So just ignoring the keys isn't ideal if those values are important...

Another note, I continued to get errors about missing keys until I mapped temp data like this:

options.RegisterKey<Dictionary<string, object>>("__ControllerTempData");

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