Value cannot be null. Parameter name: source

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Hi guys.

Having a bit of an issue with the error below I keep getting when running my code.

Error:
Value cannot be null. Parameter name: source

StackTrace:
at System.Linq.Queryable.Any[TSource](IQueryable`1 source, Expression`1 predicate)
at ietCCHPluginsCampaign.ViewModels.EditCampaign.EditCampaignViewModel.RefreshScheduleTypes() in D:\Trunk\Projects\CCH\Plugins.Campaign\iet.CCH.Plugins.Campaign\ViewModels\EditCampaign\EditCampaignViewModel.vb:line 415
at ietCCHPluginsCampaign.ViewModels.EditCampaign.EditCampaignViewModel.OnViewLoaded(Object view) in D:\Trunk\Projects\CCH\Plugins.Campaign\iet.CCH.Plugins.Campaign\ViewModels\EditCampaign\EditCampaignViewModel.vb:line 281
at Caliburn.Micro.Screen.<>c__DisplayClass12.<AttachView>b__11(Object , RoutedEventArgs )

Source of this error comes from following code:

Model.Schedules.Any(Function(x) x.Name = EachScheduleType.Name AndAlso x.Id = EachScheduleType.Id)

Does anyone have any ideas where the root of the problem may lie? I'm not sure if it's a Linq error or what.

Thanks in advance.

Posted 29-Dec-10 4:42am

Shrimpersfan

Updated 25-Oct-18 15:10pm

Not Active

v2

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Not Active · Answer 1 · 2010-12-29T04:53:00

Solution 1

When writing Linq you typically use Lamdba expressions

Model.Schedules.Any( x => x.Name == EachScheduleType.Name && x.Id == EachScheduleType.Id)

Posted 29-Dec-10 4:53am

Not Active

Comments

Shrimpersfan 29-Dec-10 10:59am

Hi Mark

By using Function(x) x.name... etc, I am indeed using a lambda expression.

[no name] 29-Dec-10 11:10am

Yes of course. Meaning that it may help to narrow the problem by using a standard approach.

Abhinav S · Answer 2 · 2010-12-29T05:02:00

Solution 2

Firt you need to make sure EachScheduleType is not null.

You can then change your lambda to
x.Name == (EachScheduleType.Name??string.empty) AndAlso x.Id == (EachScheduleType.Id??string.empty)).

I've assumed id is a string here.

Posted 29-Dec-10 5:02am

Abhinav S

Comments

Shrimpersfan 29-Dec-10 11:14am

Hi Abhinav.

Both properties are strings yes.

I can confirm that EachScheduleType is not null and it's value is being set.

I have modified the lambda but am receiving the same error message as above.