How to avoid using lambda expressions twice

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Hi, In code below I have to call same expression twice to get First Item that matches STRING. Is there any better way of doing this?

if (InvoiceDetails.Where(x => x.IMEINumber == boostReconcile.BoostSheetLine.BoostImei).Count() > 0)
                   {
                       boostReconcile.InvoiceDetail = InvoiceDetails.Where(x => x.IMEINumber == boostReconcile.BoostSheetLine.BoostImei).First();
                   }

What I have tried:

There is nothing to describe about the code.

Posted 9-Feb-16 6:25am

Qadeer Ahmed Khan

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Philippe Mori 12-Feb-16 22:46pm

Maybe, if you would look function that IntelliSense show in the dropdown you would have been able to figure out yourself the most appropriate function to use.

3 solutions

Solution 2

Try

C#

var g = InvoiceDetails.Where(x => x.IMEINumber == boostReconcile.BoostSheetLine.BoostImei);
if (g.Count() > 0)
                   {
                       boostReconcile.InvoiceDetail = g.First();
                   }

Posted 9-Feb-16 6:38am

Abhinav S

Comments

Sascha Lefèvre 9-Feb-16 12:43pm

No need to Count() all if you only need the first - Any() would be better.

Richard Deeming 9-Feb-16 12:47pm

Stop reading my mind! :)

Richard Deeming 9-Feb-16 12:46pm

That will still iterate the list / execute the query twice.

Also, it's generally better to use .Any() rather than .Count() > 0 - the only time .Count() will perform better is if the source is an ICollection<T>, which isn't the case here.

Philippe Mori 12-Feb-16 22:42pm

Almost no improvement to the original code. Only marginally better. See other solutions which are far better.

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Sascha Lefèvre · Accepted Answer · 2016-02-09T06:41:00

If it's ok to set boostReconcile.InvoiceDetail to its default value (null if it's a reference type) when there is no InvoiceDetail with a matching IMEINumber then you can do this instead:

C#

boostReconcile.InvoiceDetail = InvoiceDetails.FirstOrDefault(x => x.IMEINumber == boostReconcile.BoostSheetLine.BoostImei);

If there should ever be only 0 or 1 InvoiceDetail that matches this criterion, you should use SingleOrDefault() instead:

C#

boostReconcile.InvoiceDetail = InvoiceDetails.SingleOrDefault(x => x.IMEINumber == boostReconcile.BoostSheetLine.BoostImei);

Richard Deeming · Accepted Answer · 2016-02-09T06:35:00

Try:

C#

boostReconcile.InvoiceDetail = InvoiceDetails.FirstOrDefault(x => x.IMEINumber == boostReconcile.BoostSheetLine.BoostImei);

Enumerable.FirstOrDefault(TSource) Method (IEnumerable(TSource), Func(TSource, Boolean)) (System.Linq)[^]

NB: That will overwrite the property with null if there are no matching records. If you already have a value in the property, and you don't want to overwrite it, then try:

C#

boostReconcile.InvoiceDetail = InvoiceDetails.FirstOrDefault(x => x.IMEINumber == boostReconcile.BoostSheetLine.BoostImei) ?? boostReconcile.InvoiceDetail;

How to avoid using lambda expressions twice

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