Check null value in a list using linq
Solution 1
Using linq method of All
:
var result = Comparison.All(item => item.Value == null)
Basically what it does is to iterate all items of a collection and check a predicate for each of them. If one does not match - result is false
Solution 2
You can check by this linq statement
var isNull = Comparison.All(item => item.Value == null);
Solution 3
I'm not totally sure about the internal differences of All
and Exists
, but it might be a good idea to just check whether one of the entries is not null and then negate the result:
var result = !Comparison.Exists(o => o.Value != null);
I would expect this query to quit after the first non-null value was found and therefore to be a little more efficient.
Update: From the Enumerable.All documentation:
The enumeration of source is stopped as soon as the result can be determined.
Therefore, using All
will probably not result in the entire list getting processed after a non-null value has been found.
So the aforementioned possible performance gain is not likely to occur and both solutions probably do not differ.
Insafian
Updated on June 06, 2022Comments
-
Insafian almost 2 years
I have a list
List<OfferComparison> Comparison
. I want to check if all the items haveValue == null
in anif
condition.How can I do it with linq?
public class OfferComparison : BaseModel { public string Name { get; set; } public string Value { get; set; } public bool Valid { get; set; } }