我需要使用HttpWebRequest从C#客户端向服务器上的PHP页面传递一些数据。根据文档，预期的数据是一个数组，类似于以下内容：
$postData = array(
'label1' => 'myLabel',
'label2' => array(
'label2_1' => 3
'label2_2' => array(
'label2_2_1' => 3
)
)
);
上面的结构只是一个例子。它可能非常复杂，而且结构本身并不是恒定的。
在PHP中，有一个名为http_build_query的函数，它将这些PHP嵌套数组序列化为一个简单的字符串，该字符串可以作为HTTPPOST请求的数据发送。问题是我需要从我的C#应用程序调用这个PHP页面。我想将这些嵌套数组表示为嵌套的Dictionary<string, object>或匿名类型。
我该怎么做？http_build_query在生成输出字符串时遵循什么规则？
还有一个非常类似的问题——将PHP数组转换为C#，不幸的是，这并不能解决我的问题。公认的答案推荐了一个固定结构的解决方案，第二个根本不起作用。
好吧，.NET中似乎没有任何内置的东西可以让你做到这一点。但是，如果你想在.NET中重新实现PHP行为，你可以通过查看PHP源代码来实现它，也可以通过阅读http_build_query的PHP文档并在各种输入上测试函数来实现它。
我采用了黑盒方法，创建了以下类：
/// <summary>
/// Helps up build a query string by converting an object into a set of named-values and making a
/// query string out of it.
/// </summary>
public class QueryStringBuilder
{
private readonly List<KeyValuePair<string, object>> _keyValuePairs
= new List<KeyValuePair<string, object>>();
/// <summary> Builds the query string from the given instance. </summary>
public static string BuildQueryString(object queryData, string argSeperator = "&")
{
var encoder = new QueryStringBuilder();
encoder.AddEntry(null, queryData, allowObjects: true);
return encoder.GetUriString(argSeperator);
}
/// <summary>
/// Convert the key-value pairs that we've collected into an actual query string.
/// </summary>
private string GetUriString(string argSeperator)
{
return String.Join(argSeperator,
_keyValuePairs.Select(kvp =>
{
var key = Uri.EscapeDataString(kvp.Key);
var value = Uri.EscapeDataString(kvp.Value.ToString());
return $"{key}={value}";
}));
}
/// <summary> Adds a single entry to the collection. </summary>
/// <param name="prefix"> The prefix to use when generating the key of the entry. Can be null. </param>
/// <param name="instance"> The instance to add.
///
/// - If the instance is a dictionary, the entries determine the key and values.
/// - If the instance is a collection, the keys will be the index of the entries, and the value
/// will be each item in the collection.
/// - If allowObjects is true, then the object's properties' names will be the keys, and the
/// values of the properties will be the values.
/// - Otherwise the instance is added with the given prefix to the collection of items. </param>
/// <param name="allowObjects"> true to add the properties of the given instance (if the object is
/// not a collection or dictionary), false to add the object as a key-value pair. </param>
private void AddEntry(string prefix, object instance, bool allowObjects)
{
var dictionary = instance as IDictionary;
var collection = instance as ICollection;
if (dictionary != null)
{
Add(prefix, GetDictionaryAdapter(dictionary));
}
else if (collection != null)
{
Add(prefix, GetArrayAdapter(collection));
}
else if (allowObjects)
{
Add(prefix, GetObjectAdapter(instance));
}
else
{
_keyValuePairs.Add(new KeyValuePair<string, object>(prefix, instance));
}
}
/// <summary> Adds the given collection of entries. </summary>
private void Add(string prefix, IEnumerable<Entry> datas)
{
foreach (var item in datas)
{
var newPrefix = String.IsNullOrEmpty(prefix)
? item.Key
: $"{prefix}[{item.Key}]";
AddEntry(newPrefix, item.Value, allowObjects: false);
}
}
private struct Entry
{
public string Key;
public object Value;
}
/// <summary>
/// Returns a collection of entries that represent the properties on the object.
/// </summary>
private IEnumerable<Entry> GetObjectAdapter(object data)
{
var properties = data.GetType().GetProperties();
foreach (var property in properties)
{
yield return new Entry()
{
Key = property.Name,
Value = property.GetValue(data)
};
}
}
/// <summary>
/// Returns a collection of entries that represent items in the collection.
/// </summary>
private IEnumerable<Entry> GetArrayAdapter(ICollection collection)
{
int i = 0;
foreach (var item in collection)
{
yield return new Entry()
{
Key = i.ToString(),
Value = item,
};
i++;
}
}
/// <summary>
/// Returns a collection of entries that represent items in the dictionary.
/// </summary>
private IEnumerable<Entry> GetDictionaryAdapter(IDictionary collection)
{
foreach (DictionaryEntry item in collection)
{
yield return new Entry()
{
Key = item.Key.ToString(),
Value = item.Value,
};
}
}
}
代码非常不言自明，但它接受字典、数组或对象。如果它是顶级对象，它会序列化属性。如果它是一个数组，则每个元素都使用适当的数组索引进行序列化。如果是字典，则键/值被序列化。包含其他数组或字典的数组和字典值被展平，类似于PHPs行为。
例如，以下内容：
QueryStringBuilder.BuildQueryString(new
{
Age = 19,
Name = "John&Doe",
Values = new object[]
{
1,
2,
new Dictionary<string, string>()
{
{ "key1", "value1" },
{ "key2", "value2" },
}
},
});
// 0=1&1=2&2%5B0%5D=one&2%5B1%5D=two&2%5B2%5D=three&3%5Bkey1%5D=value1&3%5Bkey2%5D=value2
QueryStringBuilder.BuildQueryString(new object[]
{
1,
2,
new object[] { "one", "two", "three" },
new Dictionary<string, string>()
{
{ "key1", "value1" },
{ "key2", "value2" },
}
}
);
生成：
Age=19&Name=John%26Doe&Values%5B0%5D=1&Values%5B1%5D=2&Values%5B2%5D%5Bkey1%5D=value1&Values%5B2%5D%5Bkey2%5D=value2
即：
Age=19&Name=John%26Doe&Values[0]=1&Values[1]=2&Values[2][key1]=value1&Values[2][key2]=value2
Age=19
Name=John&Doe
Values[0]=1
Values[1]=2
Values[2][key1]=value1
Values[2][key2]=value2
使用NameValueCollection可以做到这一点：
private string ToQueryString(NameValueCollection queryData)
{
var array = (from key in queryData.AllKeys
from value in queryData.GetValues(key)
select string.Format(CultureInfo.InvariantCulture, "{0}={1}", HttpUtility.UrlEncode(key), HttpUtility.UrlEncode(value)))
.ToArray();
return "?" + string.Join("&", array);
}