C # Equivalent to PHP http_build_query

Question

I need to transfer some data to a PHP page on the server from my C # client using HttpWebRequest . The expected data according to the documentation is an array of arrays, something like this:

 $postData = array( 'label1' => 'myLabel', 'label2' => array( 'label2_1' => 3 'label2_2' => array( 'label2_2_1' => 3 ) ) ); 

The structure given above is just an example. This can be very difficult, and the structure itself is not constant.

PHP has a function called http_build_query that serializes these nested PHP arrays with a simple string that can be sent as HTTP POST request data. The problem is that I need to call this PHP page from my C # application. I would like to introduce these nested arrays as nested Dictionary<string, object> s, as well as anonymous types.

How can i do this? What rules does http_build_query to create its output string?

There is a very similar question Converting an array of PHP arrays to C # , which, unfortunately, does not solve my problem. The accepted answer recommends a solution for a fixed structure, the second does not work at all.

Answer 1

Well, there seems to be nothing built into .NET for you to do this. However, if you want to re-implement PHP behavior in .NET, you can either implement it, either look at the PHP source code, or implement it in a black box by reading the PHP Documentation http_build_query and testing the function on different inputs.

I took the black box approach and created the following class:

 /// <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 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, }; } } } 

The code is pretty straightforward, but it takes a dictionary, array, or object. If it is a top-level object, it serialized the properties. If it is an array, each element is serialized with the corresponding array index. If it is a dictionary, key / values ​​are serialized. Arrays and dictionary values ​​containing other arrays or dictionaries are smoothed, as is the behavior of PHP.

For example, the following:

 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" }, } } ); 

Forms:

 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 

which the:

 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 

Answer 2

Using NameValueCollection, you can do this:

 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); }