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I am working on a query tools, which is based on dynamic Linq.

I have the following code in LinqPad:

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List<object> list=new List<object>();

list.Add(Categories.First());

list.Add(Products.Take (10));

list.Select(p=>new {name=p.GetType().Name,countOfProducts=(p as IEnumerable<Products>).Count()}).Dump();

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It will throw an exception :
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Value cannot be null. Parameter name: source
Message Value cannot be null.
Parameter name: source
ParamName source

Data
InnerException null
TargetSite 6RuntimeMethodInfo
Enumerable.Count (IEnumerable<TSource> source)
Name Count

...
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Of course, If I don't add the category to the list in the code, all works fine.

Why do I try this? It is because I want to have a data favorites, so that I can add all kinds of object in the list. But I want to know the object's count of its children if it is an IEnumerable<>. Or I hope it will return null, 0 at least.

I was blocked here.

Thank you in advance for all kinds of suggestions.



Ying

You could write a custom method to help here:




Joe