Checking for null values in quickbooks using QBFC

Question

I am trying to get the list of items inside of a quickbooks database. I have the following snippet of code:

                    IItemServiceRet itemServiceRet = itemRet.ItemServiceRet;

                    TestItem item = new TestItem();
                    item.Name = itemServiceRet.Name.GetValue();
                    item.Desc = itemServiceRet.ORSalesPurchase.SalesOrPurchase.Desc.GetValue();
                    item.Rate = itemServiceRet.ORSalesPurchase.SalesOrPurchase.ORPrice.Price.GetValue().ToString();
                    item.ItemType = "Service";
                    item.QBID = itemServiceRet.ListID.GetValue();
                    item.EditSeq = itemServiceRet.EditSequence.GetValue();

The code fails on the line:

item.Desc = itemServiceRet.ORSalesPurchase.SalesOrPurchase.Desc.GetValue();
"Object reference not set to an instance of an object"

Because that particular service item in the QB database does not have a description. I was curious if there was a 'clean' way to check for null values without having to have each line include an if statement checking if GetValue() returns null?

Edit: After trying Andrew Cooper's solution of:

item.Desc = itemServiceRet.ORSalesPurchase.SalesOrPurchase.Desc == null ? null : itemServiceRet.ORSalesPurchase.SalesOrPurchase.Desc.GetValue();

It still throws the exception:

Object reference not set to an instance of an object

Its as if GetValue() returns nothing at all if there is no description, which wouldn't make much sense.

item.Desc is looking for a value. So you would have to do put empty string instead of null. Also you might have to use a simple If Then, and not the Ternary operator. — user890332, Aug 27 '15 at 20:44

score 3 · Answer 1 · answered Jun 23 '14 at 16:59

3

You could use the ternary operator like this:

item.Desc = itemServiceRet.ORSalesPurchase.SalesOrPurchase.Desc == null ? null : itemServiceRet.ORSalesPurchase.SalesOrPurchase.Desc.GetValue();

But that's pretty ugly.

Best bet is to create a helper method that takes whatever type Desc and wraps the above logic.

answered Jun 23 '14 at 16:59

Andrew Cooper

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I tried that and I still get "Object Reference not set to an instance of an object" Its as if GetValue() is not returning null if nothing is there, but is returning nothing at all. – Giardino Jun 23 '14 at 17:03
1

It's the property `Desc` that is null. Calling `.GetValue()` on a null reference is the source of the exception. If `Desc` has a non-null value then `.GetValue()` will work okay. – Andrew Cooper Jun 23 '14 at 17:11

score 1 · Answer 2 · answered Jun 26 '14 at 12:58

I don't think there's any better solution, as you can't access the functions of a null object. I typically create a constructor for my items that does the checking so I only have to do that once. So in your example:

TestItem item = new TestItem(itemRet.ItemServiceRet);

The constructor would look like this:

public TestItem(IItemServiceRet i)
{
    if(i.Name != null) this.Name = i.Name.GetValue();
    if(i.ORSalesPurchase != null)
        if(i.ORSalesPurchase.SalesOrPurchase != null)
        {
            if(i.ORSalesPurchase.SalesOrPurchase.Desc != null) this.Desc = i.ORSalesPurchase.SalesOrPurchase.Desc.GetValue();
            if(i.ORSalesPurchase.SalesOrPurchase.ORPrice != null)
                if(i.ORSalesPurchase.SalesOrPurchase.ORPrice.Price != null) this.Price = i.ORSalesPurchase.SalesOrPurchase.ORPrice.Price.GetValue();
        }
}

Keep in mind that this does work well for strings, as an empty string is usually the same as a blank field, but for number fields in QuickBooks this may cause problems. For example, an Invoice line can have a blank quantity field (which is a double). A double will default to the value of 0.0, but a blank quantity field in QuickBooks is treated as a quantity of 1.0. This can also cause problems with dates, as QuickBooks can have null date fields.

Checking for null values in quickbooks using QBFC

2 Answers2