Extension Method instead of Null Object Template

Question

I am interested in using the extension method to avoid checking for a null value in the hierarchy. Example:

// GetItems(), GetFirstOrDefault(), GetProduct(), GetIDProduct() are extension methods like:
public static SomeType GetSomeProperty( this XYZ obj ) {
    if ( object.ReferenceEquals( obj, null ) ) { return default( SomeType ); }
    return obj.SomeProperty;
}

// the code with extension methods
Guid? idProduct = this.Invoice.GetItems().GetFirstOrDefault().GetProduct().GetIDProduct();
// instead of
Guid? idProduct = null;
Invoice invoice = this.Invoce;
if ( null != invoice ) {
    InvoiceItems items = invoice.Items;
    if ( null != items && items.Count > 0 ) {
        InvoiceItem item = items[0];
        if ( null != item ) {
            idProduct = item.IDProduct();
        }
    }
}

I know that there is a Null Object pattern, but a solution with such extension methods looks better.

Do you think this decision is good or bad (because the design is bad / good, clarity, something else)?

Please vote "Good" or "Bad" and why you think so. Messages are shared as a community.

Answer 1

I would just do it great:

Guid? idProduct = null;
Invoice invoice = this.Invoce;

if (invoice != null && 
    invoice.Items != null &&
    invoice.Items.Count > 0 &&
    invoice.Items[0] != null) 
{
   idProduct = invoice.Items[0].IDProduct();
}

Answer 2

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Answer 3

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Answer 4

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GetFirstOrDefault().GetProduct()

: 1) Get, , 2) "" , Null Object. OrDefault null,

GetFirst().GetProduct()

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Answer 5

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