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，但收到此错误：Collection is read-only.

我如何将它们组合成一个，所以我可以访问两者中的所有元素？

Answer 1

要合并集合，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集合来访问组合设置。

Answer 2

我尝试了customTag.Add(appSetting);方法，但收到此错误：Collection is read-only.

这意味着customTag对象是只读的，无法写入。 .Add尝试修改原始NameValueCollection。 System.Configuration包含一个扩展ReadOnlyNameValueCollection的{{1}}以使其只读，因此尽管转换为通用NameValueCollection，该对象仍然是只读的。

我如何将它们组合成一个，所以我可以访问两者中的所有元素？

您只需将两个集合添加到第三个可写NameValueCollection。

假设：

NameValueCollection

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

.Add

但是，var collection = new NameValueCollection(); collection.Add(customTag); collection.Add(appSettings);构造函数有一个在内部调用NameValueCollection的简写：

Add

请注意，在这两种情况下，使用var collection = new NameValueCollection(customTag); collection.Add(appSettings);都会允许将多个值添加到每个键中。

例如，如果要合并Add和{foo: "bar"}，结果将为{foo: "baz"}（JSON语法用于简洁）。

Answer 3

zzzzBov的答案已完成。但是，如果要合并多个NameValueCollection或不修改任何原始NameValueCollection，可以考虑以下方法合并任意数量的NameValueCollection。

<强>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;
}

使用示例

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()，只需返回空NameValueCollection。这将确保您的代码不会因输入错误而抛出异常。

如何组合两个NameValueCollection？

3 个答案: