How to loop through WebHeaderCollection

Question

How do you loop through a WebHeaderCollection got from HttpWebResponse in Windows phone 7 to get keys and values? We've tried Enumerator.Current; with this, we are only getting the keys, not the values. We are doing this to get a redirected URL.

Answer 1

That's an awful collection, I think.

See MSDN sample. I'd prefer this one:

var headers = new System.Net.WebHeaderCollection();
headers.Add("xxx", "yyy");
headers.Add("zzz", "fff");
headers.Add("xxx", "ttt");
for(int i = 0; i < headers.Count; ++i)
{
    string header = headers.GetKey(i);
    foreach(string value in headers.GetValues(i))
    {
        Console.WriteLine("{0}: {1}", header, value);
    }
}

Unfortunately there is no way to get values with order preserving between other headers.

P.S. Linq style (in LINQPad)

var items = Enumerable
                .Range(0, headers.Count)
                .SelectMany(i => headers.GetValues(i)
                    .Select(v => Tuple.Create(headers.GetKey(i), v))
                );
items.Dump();

Answer 2

foreach(string key in resp.AllKeys)
{
string value = resp[key];
}

Answer 3

in WP7/Silverlight I do this.

foreach (string key in headers.AllKeys)
{
   Console.WriteLine("Header : " + key + " ---> " + headers[key]);
}

Answer 4

How about some C# 6 :)

string.Join("&", headers.AllKeys.Select(key => $"{key}={headers[key]}").ToList());

Answer 5

In Silverlight.

If you want the keys and values one by one:

foreach (string key in webHeaderCollection)
{
    var value = webHeaderCollection[key];
    // do something with key and value
}

If you want a dictionary of keys and values:

var dic = webHeaderCollection.AllKeys.ToDictionary(k => webHeaderCollection[k]);
foreach (var pair in MyDic)
{
    // do something with pair.Key and pair.Value
}

Answer 6

I really don't like it when special collections like this exist at times in .NET that are not easily iterated over for expected values. Makes things a lot less user friendly. Anyway, if you felt like going to the trouble of adding an extension method:

// call in your main code
KeyValuePair<string, string>[] headers = webResponse.Headers.GetHeaders();

// extension: 
public static class Xtension
{
    public static KeyValuePair<string, string>[] GetHeaders(this WebHeaderCollection webHeaderCollection)
    {
        string[] keys = webHeaderCollection.AllKeys;
        var keyVals = new KeyValuePair<string, string>[keys.Length];
        for (int i = 0; i < keys.Length; i++)
            keyVals[i] = new KeyValuePair<string, string>(keys[i], webHeaderCollection[keys[i]]);
        return keyVals;
    }
}

Answer 7

I landed on this question from Google while I was trying to find a way to view the key-value pairs in a WebHeaderCollection from the Visual Studio debugger.

Simple solution (in retrospect): The WebHeaderCollection.ToString() method, used in the Watch debugging window, will accomplish this:

webheadercollection.ToString()

So, if you have an HttpWebRequest named request:

request.Headers.ToString()

Answer 8

My solution, as an extension method:

private static string Serialize(this System.Net.WebHeaderCollection value)
{
    var response = new System.Text.StringBuilder();
    foreach (string k in value.Keys)
        response.AppendLine(k + ": " + value[k]);
    return response.ToString();
}

Answer 9

If you really want to use extension method to achieve getting list of headers as KeyValuePair array you may want to use IEnumerable interface.

public static class WebHeaderCollectionExtensions
{
    public static IEnumerable<KeyValuePair<string, string>> GetHeaders(this System.Net.WebHeaderCollection webHeaderCollection)
    {
        string[] keys = webHeaderCollection.AllKeys;
        for (int i = 0; i < keys.Length; i++)
        {
            yield return new KeyValuePair<string, string>(keys[i], webHeaderCollection[keys[i]]);
        }
    }
}

In this case you can iterate in foreach loop easy way:

foreach (var x in h.GetHeaders())
{
    Console.WriteLine(x.Key + ": " + x.Value);
}

//fix without extensions

public static IEnumerable<KeyValuePair<string, string>> GetHeaders(System.Net.WebHeaderCollection webHeaderCollection)
{
    string[] keys = webHeaderCollection.AllKeys;
    for (int i = 0; i < keys.Length; i++)
    {
        yield return new KeyValuePair<string, string>(keys[i], webHeaderCollection[keys[i]]);
    }
}

foreach (var x in GetHeaders(h))
{
    Console.WriteLine(x.Key + ": " + x.Value);
}

Answer 10

Extension method for your library:

public static IEnumerable<KeyValuePair<string, string>> AsEnumerable(this WebHeaderCollection headers) =>
    headers.AllKeys.Select(k => new KeyValuePair<string, string>(k, headers[k])).AsEnumerable();

Answer 11

For i As Integer = 0 To Response.Headers.Count - 1
   'Response.Headers.Get(i)
Next

Answer 12

foreach(string item in response.Headers) {
  string key = item.ToString();
      if (key == "x-ng-sessionid") {
         sessionid = response.Headers[item];
         }
      }