'Not able to use GetValueOrDefault() for Dictionary in C#

I've defined a Dictionary with some custom type like this,

 public readonly Dictionary<PricingSection, View> _viewMappings = new Dictionary<PricingSection, View>();

Now when i try to do 

_viewMappings.GetValueOrDefault(section);

section is of type PricingSection

i'm getting an error saying

Severity Code Description Project File Line Suppression State Error CS1061 'Dictionary' does not contain a definition for 'GetValueOrDefault' and no accessible extension method 'GetValueOrDefault' accepting a first argument of type 'Dictionary' could be found (are you missing a using directive or an assembly reference?)

Am i missing something ??

c++sharpdictionaryxamarin.forms.net-standard


Solution 1:[1]

GetValueOrDefault() is part of ImmutableDictionary. so of course you get the error message. instead use

Dictionary.TryGetValue(TKey, TValue)

Solution 2:[2]

When I encountered the same problem, I was just missing this:

using System.Collections.Generic

As mentioned by @guyarad, this is an extension method on IReadOnlyDictionary but it needs to be imported. It seems obvious, but since you can use a returned dictionary without the import, it can be confusing when it mostly works but is missing some functionality you're pretty sure it should have.

Solution 3:[3]

I use it in .Net Core (3.1)

class Dictionary<TKey, TValue> implements IReadOnlyCollection<KeyValuePair<TKey, TValue>>.

and there is and extension method in namespace System.Collections.Genericfor for IReadOnlyDictionary:

public static class CollectionExtensions
{
     ...
     public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key) where TKey : notnull;
     ...
}

so we get it out of the box also for Dictionary<TKey, TValue>.

(Not sure about .net framework which going to be obsolete anyway)

Sources

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Source: Stack Overflow

Solution Source
Solution 1
Solution 2 Benjamin Smith
Solution 3 Aviko

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