CODEWITHSUNDEEP
c#linqlambdaresharperternary-operator
jaekie
jaekie

Reputation: 2303

Alternative to using a ternary operator in Lambda

Currently.. my code looks like this.

PhoneNumber = x.PhoneNumbers.FirstOrDefault() != null ? x.PhoneNumbers.FirstOrDefault().PhoneNumber : string.Empty,

PhoneNumbers is an ICollection<PhoneNumber>

This is also in a .Select(), so I can't really create a variable for it outside.

Resharper is complaining that x.PhoneNumbers.FirstOrDefault() could be null, and to be honest, not sold on the idea that I gotta do a FirstOrDefault twice.

Any other ideas, I'm thinking there could be another Lambda method I can do something similar.

Upvotes: 4

Views: 2175

Answers (3)

Carlos Hidalgo
Carlos Hidalgo

Reputation: 1

var result = new List<Product>();

result = result.Where(o => o.Name == (string.IsNullOrEmpty(_nameParameter) ? o.Name : _nameParameter)).ToList();

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1500055

First option, like Markus's:

PhoneNumber = x.PhoneNumbers.Select(x => x.PhoneNumber)
                            .FirstOrDefault() ?? "";

Another alternative:

PhoneNumber = x.PhoneNumbers.Select(x => x.PhoneNumber)
                            .DefaultIfEmpty("")
                            .First();

Or if you find yourself doing this a lot, you could write your own method to combine the two:

public static TElement ProjectedFirstOrDefault<TSource, TElement>
    (this IEnumerable<TSource> source,
     Func<TSource, TElement> selector,
     TElement defaultValue) where TElement : class
{
    var firstElement = source.FirstOrDefault();
    return firstElement == null ? defaultValue : selector(firstElement);
}

Then:

PhoneNumber = x.PhoneNumbers.ProjectedFirstOrDefault(x => x.PhoneNumber, "");

Upvotes: 8

Markus Jarderot
Markus Jarderot

Reputation: 89171

PhoneNumber = x.PhoneNumbers.Select(pn => pn.PhoneNumber).FirstOrDefault() ?? "",

Upvotes: 12

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