Null processing for ${aspnet-session:Variable=User.Name:EvaluateAsNestedProperties=true}

[worldofsites]

Session["user"] = new UserInfo { Name= "johnDoe", Id = 100};
layout="${aspnet-session:Variable=User.Name:EvaluateAsNestedProperties=true}"

I think there need to null check for Session["user"].
If object is not null, then try to read property of that object, else return.

From NLog.Web.Internal => PropertyReader => method GetPropertyInfo:
return value.GetType().GetProperty(propertyName); // "value" can be null here.
Thanks.

[UgurAldanmaz]

Thanks for your proposal.

Did you try it with null value? If yes, what is the result?

[worldofsites]

Yes, sure, I tried with null value. And exception is:
System.NullReferenceException in NLog.Web.Internal.PropertyReader.GetPropertyInfo(Object value, String propertyName)
Also I tried that hack in config:
${when:when='${aspnet-session:Variable=User}' != null:inner='${aspnet-session:Variable=User.Name:EvaluateAsNestedProperties=true}'}
But to no avail

[UgurAldanmaz]

So null checking would be useful. But we need to check the side affects.

What do you tkink @304NotModified?

[304NotModified]

I think this is the best approach:

I think there need to null check for Session["user"].
If object is not null, then try to read property of that object, else return.

[UgurAldanmaz]

I just opened a bug fix issue for this, #70

@worldofsites,
By the way, you are trying to read User.Name

${when:when='${aspnet-session:Variable=User}' != null:inner='${aspnet-session:Variable=User.Name:EvaluateAsNestedProperties=true}'}

but it is actually UserInfo

Session["user"] = new UserInfo { Name= "johnDoe", Id = 100};

Is it just a typo in the issue or could it be the reason?

Thanks for reporting!

[worldofsites]

@UgurAldanmaz
Key in session = "user", so => in config 'Variable' should "User".
As in https://github.com/NLog/NLog/wiki/AspNetSession-Layout-Renderer
And also it's just example. I tried with the real data with another session keys.

[UgurAldanmaz]

You are right. Sorry for my oversight.

[worldofsites]

@UgurAldanmaz @304NotModified
Also, about "Variable" values:
Please check nullable context places in "...ValueLayout.." classes, for example AspNetRequestValueLayoutRenderer.cs
var httpRequest = HttpContextAccessor.HttpContext.TryGetRequest();
should be
var httpRequest = HttpContextAccessor?.HttpContext?.TryGetRequest();
like in AspNetRequestUrlRenderer.cs
Because all elements of the chain can be null. I tried that and can confirm.
Thanks.

[304NotModified]

PS it's OK for me to move to VS2015 (C# 6)