如何合并两个 NameValueCollection？

Question

我有两个 NameValueCollections：

NameValueCollection customTag = (NameValueCollection)System.Configuration.ConfigurationManager.GetSection("secureAppSettings");
NameValueCollection appSetting = (NameValueCollection)System.Configuration.ConfigurationManager.GetSection("appSettings");

我尝试了 customTag.Add(appSetting); 方法，但出现此错误：Collection is read-only.

我如何将它们合并为一个，以便我可以访问两者的所有元素？

Answer 1

要组合这些集合，请尝试以下操作：

var secureSettings = (NameValueCollection)System.Configuration.ConfigurationManager.GetSection("secureAppSettings");
var appSettings = (NameValueCollection)System.Configuration.ConfigurationManager.AppSettings;

// Initialise a new NameValueCollection with the contents of the secureAppSettings section
var allSettings = new NameValueCollection(secureSettings);
// Add the values from the appSettings section
foreach (string key in appSettings)
{
    // Overwrite any entry already there
    allSettings[key] = appSettings[key];
}

使用新的 allSettings 集合访问组合设置。

Answer 2

I tried customTag.Add(appSetting); method but I get this error: Collection is read-only.

这意味着 customTag 对象是只读的，不能写入。 .Add 尝试修改原始 NameValueCollection。 System.Configuration 包含一个 ReadOnlyNameValueCollection 扩展 NameValueCollection 以使其成为只读的，因此尽管转换为通用 NameValueCollection，该对象仍然是只读的。

How would I combine them to one, so i can access all the elements from both?

您只需将这两个集合添加到第三个可写集合 NameValueCollection。

给定：

var customTag = (NameValueCollection)System.Configuration.ConfigurationManager.GetSection("secureAppSettings");
var appSetting = (NameValueCollection)System.Configuration.ConfigurationManager.GetSection("appSettings");

你可以.Add两者：

var collection = new NameValueCollection();
collection.Add(customTag);
collection.Add(appSettings);

但是，NameValueCollection 构造函数有一个 shorthand 在内部调用 Add：

var collection = new NameValueCollection(customTag);
collection.Add(appSettings);

请注意，在这两种情况下，使用 Add 将允许向每个键添加多个值。

例如，如果您要合并 {foo: "bar"} 和 {foo: "baz"}，结果将是 {foo: ["bar", "baz"]}（JSON 语法用于简洁）。

Answer 3

的回答已完成。但是，如果你想合并多个 NameValueCollection 或者不修改任何原始的，你可以考虑以下方法合并任意数量的 NameValueCollection.

代码

/// <summary>
/// Merges the specified NameValueCollection arguments into a single NamedValueCollection.
/// </summary>
/// <param name="args">An array of NameValueCollection to be merged.</param>
/// <returns>Merged NameValueCollection</returns>
/// <remarks>
/// Returns an empty collection if args passed are null or empty.
/// </remarks>
static NameValueCollection Merge(params NameValueCollection[] args)
{
    NameValueCollection combined = new NameValueCollection();

    if (args == null || args.Length == 0)
    {
        return combined;
    }

    NameValueCollection current = null;
    for (int i = 0; i < args.Length; i++)
    {
        current = args[i];

        if (current != null && current.Count > 0)
        {
            combined.Add(current);
        }
    }

    return combined;
}

示例用法

NameValueCollection northAmericaCollection = new NameValueCollection
{
    { "Cananda", "Ottawa" },
    { "USA", "Washington, D.C." },
    { "Mexico", "Mexico City" }
};

NameValueCollection southAmericaCollection = new NameValueCollection
{
    { "Argentina", "Buenos Aires" },
    { "Peru", "Lima" },
    { "Chile", "Santiago" }
};

NameValueCollection merged = Merge(northAmericaCollection, null, southAmericaCollection, null);

for (int i = 0; i < merged.Count; i++)
{
    Console.WriteLine("Name: {0}, Value: {1}", merged.GetKey(i), merged.Get(i));
}

// The example displays the following output:
//      Name: Cananda, Value: Ottawa
//      Name: USA, Value: Washington, D.C.
//      Name: Mexico, Value: Mexico City
//      Name: Argentina, Value: Buenos Aires
//      Name: Peru, Value: Lima
//      Name: Chile, Value: Santiago

该方法也足够强大，可以承受 Merge(null) 或 Merge()，并且只需 return 一个空的 NameValueCollection。这将确保您的代码不会因为输入错误而引发异常。

如何合并两个 NameValueCollection？

How to combine two NameValueCollections?

c#

asp.net

collections