如何将 KeyValuePair 转换为字典，因为 ToDictionary 在 c# 中不可用？
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How to convert KeyValuePair to Dictionary as ToDictionary is not available in c#?
提问by Robin Joseph
How to convert KeyValuePairto Dictionary, since ToDictionaryis not available in C#?
如何转换KeyValuePair为字典，因为ToDictionary在 C# 中不可用？
采纳答案by jwg
var dictionary = new Dictionary<string, object> { { kvp.Key, kvp.Value } };
ToDictionarydoesexist in C# (edit: not the same ToDictionaryyou were thinking of) and can be used like this:
ToDictionary确实存在于 C# 中（编辑：与ToDictionary您想的不一样）并且可以这样使用：
var list = new List<KeyValuePair<string, object>>{kvp};
var dictionary = list.ToDictionary(x => x.Key, x => x.Value);
Here listcould be a Listor other IEnumerableof anything. The first lambda shows how to extract the key from a list item, and the second shows how to extract the value. In this case they are both trivial.
这里list可能是一个List或其他IEnumerable任何东西。第一个 lambda 显示如何从列表项中提取键，第二个显示如何提取值。在这种情况下，它们都是微不足道的。
回答by JSJ
Create a collection of KeyValuePairand make sure System.Linq is imported in a usingstatement.
创建一个KeyValuePair集合并确保 System.Linq 在using语句中导入。
Then you will be able to see the .ToDictionary()extension method.
然后你就可以看到 . ToDictionary()扩展方法。
public IList<KeyValuePair<string, object>> MyDictionary { get; set; }
回答by br1
Implement it yourself as an extension method.
自己将其实现为扩展方法。
public static class MyExtensions
{
public static Dictionary<T1,T2> ToDictionary<T1, T2>(this KeyValuePair<T1, T2> kvp)
{
var dict = new Dictionary<T1, T2>();
dict.Add(kvp.Key, kvp.Value);
return dict;
}
}
see this in action: https://dotnetfiddle.net/Ka54t7
回答by BartoszKP
If I understand correctly you can do it as follows:
如果我理解正确，您可以按如下方式进行：
new[] { keyValuePair }.ToDictionary(kvp => kvp.Key, kvp => kvp.Value);
回答by Simon Whitehead
Alternatively (if you can't use Linq.. although I'm curious why..).. implement ToDictionaryyourself...
或者（如果你不能使用 Linq ......虽然我很好奇为什么......）..ToDictionary自己实现......
public static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement>(IEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector) {
if (source == null)
{
throw new ArgumentNullException("source");
}
if (keySelector == null) {
throw new ArgumentNullException("keySelector");
}
if (elementSelector == null) {
throw new ArgumentNullException("elementSelector");
}
var dictionary = new Dictionary<TKey, TElement>();
foreach (TSource current in source) {
dictionary.Add(keySelector(current), elementSelector(current));
}
return dictionary;
}
Example usage:
用法示例：
var kvpList = new List<KeyValuePair<int, string>>(){
new KeyValuePair<int, string>(1, "Item 1"),
new KeyValuePair<int, string>(2, "Item 2"),
};
var dict = ToDictionary(kvpList, x => x.Key, x => x.Value);
