C# 将键值从 NameValueCollection 复制到通用字典

Copy key values from NameValueCollection to Generic Dictionary

提问by Kobojunkie

Trying to copy values from an existing NameValueCollection object to a Dictionary. I have the following code below to do that but seems the Add does not accept that my keys and values are as Strings

尝试将现有 NameValueCollection 对象中的值复制到 Dictionary。我有下面的代码来做到这一点，但似乎 Add 不接受我的键和值是字符串

IDictionary<TKey, TValue> dict = new Dictionary<TKey, TValue>();
public void copyFromNameValueCollection (NameValueCollection a)
{
    foreach (var k in a.AllKeys)
    { 
        dict.Add(k, a[k]);
    }  
}

Note:NameValueCollection contains String keys and values and so I simply want to provide here a method to allow copying of those to a genericdictionary.

注意：NameValueCollection 包含字符串键和值，所以我只想在这里提供一种方法来允许将它们复制到通用字典中。

采纳答案by Lee

It doesn't make sense to use generics here since you can't assign strings to some arbitrary generic type:

在这里使用泛型没有意义，因为您不能将strings分配给某个任意的泛型类型：

IDictionary<string, string> dict = new Dictionary<string, string>();

public void copyFrom(NameValueCollection a)
{
            foreach (var k in a.AllKeys)
            { 
                dict.Add(k, a[k]);
            }  
}

although you should probably create a method to create a new dictionary instead:

尽管您可能应该创建一种方法来创建新字典：

public static IDictionary<string, string> ToDictionary(this NameValueCollection col)
{
    IDictionary<string, string> dict = new Dictionary<string, string>();
    foreach (var k in col.AllKeys)
    { 
        dict.Add(k, col[k]);
    }  
    return dict;
}

which you can use like:

你可以像这样使用：

NameValueCollection nvc = //
var dictionary = nvc.ToDictionary();

If you want a general way of converting the strings in the collection into the required key/value types, you can use type converters:

如果您想要将集合中的字符串转换为所需的键/值类型的通用方法，您可以使用类型转换器：

public static Dictionary<TKey, TValue> ToDictionary<TKey, TValue>(this NameValueCollection col)
{
    var dict = new Dictionary<TKey, TValue>();
    var keyConverter = TypeDescriptor.GetConverter(typeof(TKey));
    var valueConverter = TypeDescriptor.GetConverter(typeof(TValue));

    foreach(string name in col)
    {
        TKey key = (TKey)keyConverter.ConvertFromString(name);
        TValue value = (TValue)valueConverter.ConvertFromString(col[name]);
        dict.Add(key, value);
    }

    return dict;
}

回答by Reed Copsey

If you know that your dictionary is always going to contain strings, specify it to contain strings instead of making your class generic:

如果你知道你的字典总是包含字符串，指定它包含字符串而不是让你的类泛型：

IDictionary<string, string> dict = new Dictionary<string, string>();

With this, things will "just work" as written (without the generic method specification).

有了这个，事情将“正常工作”（没有通用方法规范）。

If you need this to be a generic class, and hold generic data, you need some way to convert from stringto TKeyand stringto TValue. You could provide delegates to your copy method to do this:

如果您需要将其作为泛型类并保存泛型数据，则需要某种方式来从stringtoTKey和stringto进行转换TValue。您可以为您的复制方法提供委托来执行此操作：

public void CopyFrom(NameValueCollection a, Func<string, TKey> keyConvert, Func<string, TValue> valueConvert)
{
    foreach(var k in a.AllKeys)
    {
         dict.Add(keyConvert(k), valueConvert(a[k]));
    }
}

You would then need to pass a delegate in that would perform the conversion from string to TValueand string to TKey.

然后，您需要传递一个委托来执行从 string toTValue和 string to的转换TKey。

回答by abatishchev

Use LINQ:

使用 LINQ：

public static IDictionary<string, string> ToDictionary(this NameValueCollection collection)
{
    return collection.Cast<string>().ToDictionary(k => k, v => collection[v]);
}

Usage:

用法：

IDictionary<string, string> dic = nv.ToDictionary();

回答by katbyte

Extension method plus linq:

扩展方法加linq：

 public static Dictionary<string, string> ToDictionary(this NameValueCollection nvc) {
    return nvc.AllKeys.ToDictionary(k => k, k => nvc[k]);
 }

 //example
 var dictionary = nvc.ToDictionary();

回答by 1232133d2ffa

Super-Short Version

超短版

var dataNvc = HttpUtility.ParseQueryString(data);
var dataCollection = dataNvc.AllKeys.ToDictionary(o => o, o => dataNvc[o]);

回答by Chobits

parameters.AllKeys.ToDictionary(t => t, t => parameters[t]);

回答by Dmitriy Dokshin

You should not forget about EqualityComparer. But it is not a public property. So, you should use reflection to get it.

你不应该忘记 EqualityComparer。但它不是公共财产。所以，你应该使用反射来获取它。

public static IEqualityComparer GetEqualityComparer(this NameObjectCollectionBase nameObjectCollection)
  {
  PropertyInfo propertyInfo = typeof(NameObjectCollectionBase).GetProperty("Comparer", BindingFlags.Instance | BindingFlags.NonPublic);
  return (IEqualityComparer)propertyInfo.GetValue(nameObjectCollection);
  }

public static IEqualityComparer<string> GetEqualityComparer(this NameValueCollection nameValueCollection)
  {
  return (IEqualityComparer<string>)((NameObjectCollectionBase)nameValueCollection).GetEqualityComparer();
  }

public static Dictionary<string, string> ToDictionary(this NameValueCollection nameValueCollection)
  {
  Dictionary<string, string> dictionary =
    nameValueCollection.AllKeys.ToDictionary(x => x, x => nameValueCollection[x], nameValueCollection.GetEqualityComparer());
  return dictionary;
  }