Program.cs

using Newtonsoft.Json;
using System;
using System.Net.Http;
using System.Threading.Tasks;
using System.Net.Http.Formatting;
using System.Threading;

namespace REST_from.NET
{
    //This is used when executing a query via REST
    //DocumentDB expects a specific Content-Type for queries
    //When setting the Content-Type header it must not have a charset, currently. 
    //This custom class sets the correct Content-Type and clears the charset
    public class NoCharSetJsonMediaTypeFormatter : JsonMediaTypeFormatter
    {
        public override void SetDefaultContentHeaders(Type type, System.Net.Http.Headers.HttpContentHeaders headers, System.Net.Http.Headers.MediaTypeHeaderValue mediaType)
        { 
            base.SetDefaultContentHeaders(type, headers, new System.Net.Http.Headers.MediaTypeHeaderValue("application/query+json"));
            headers.ContentType.CharSet = "";
        }
    }

    //A custom extension of HttpClient that adds a new PostWithNoCharSet async method
    //that uses the custom MediaTypeFormatter class to post with the correct Content-Type header
    public static class HttpClientExtensions
    {
        public static async Task<HttpResponseMessage> PostWithNoCharSetAsync<T>(this HttpClient client, Uri requestUri, T value) { return await client.PostAsync(requestUri, value, new NoCharSetJsonMediaTypeFormatter()); }
    }

    class SqlQuerySpec
    {
        public string query { get; set; }
    }

    class Program
    {
        static readonly string endpoint = "";
        static readonly string masterKey = "";
        static readonly Uri baseUri = new Uri(endpoint);

        //DocumentDB supports two different ways of addressing resources,
        //This sample shows you how to deal with both ways. 
        //Uncomment the appropriate code below based on the way you prefer to address resources

        //1. Using internal resource ids (_rid). These are encoded ids that are generated by the system
        //static readonly string databaseId = "prdnAA==";
        //static readonly string collectionId = "prdnAIbaDQA=";
        //static readonly string documentId = "prdnAIbaDQAGAAAAAAAAAA==";
        //static bool idBased = false;

        //2. User settable ids (id). These are the id values you give a resource when you create it
        static readonly string databaseId = "sandpit";
        static readonly string collectionId = "data";
        static readonly string documentId = "test";
        static bool idBased = true;

        static readonly string utc_date = DateTime.UtcNow.ToString("r");


        static void Main(string[] args)
        {
            var client = new System.Net.Http.HttpClient();
            string response = string.Empty;
            string authHeader = string.Empty;
            string verb = string.Empty;
            string resourceType = string.Empty;
            string resourceId = string.Empty;
            string resourceLink = string.Empty;

            client.DefaultRequestHeaders.Add("x-ms-date", utc_date);
            client.DefaultRequestHeaders.Add("x-ms-version", "2015-08-06");

            //LIST all databases
            verb = "GET";
            resourceType = "dbs";
            resourceId = string.Empty;
            resourceLink = string.Format("dbs");

            authHeader = GenerateMasterKeyAuthorizationSignature(verb, resourceId, resourceType, masterKey, "master", "1.0");

            client.DefaultRequestHeaders.Remove("authorization");
            client.DefaultRequestHeaders.Add("authorization", authHeader);

            response = client.GetStringAsync(new Uri(baseUri, resourceLink)).Result;
            
            Console.WriteLine(response);
            Console.ReadKey();

            //GET a database
            verb = "GET";
            resourceType = "dbs";
            resourceLink = "dbs/" + databaseId;
            resourceId = (idBased) ? resourceLink : databaseId.ToLowerInvariant();

            authHeader = GenerateMasterKeyAuthorizationSignature(verb, resourceId, resourceType, masterKey, "master", "1.0");

            client.DefaultRequestHeaders.Remove("authorization");
            client.DefaultRequestHeaders.Add("authorization", authHeader);

            response = client.GetStringAsync(new Uri(baseUri, resourceLink)).Result;
            
            Console.WriteLine(response);
            Console.ReadKey();


            //LIST all collections
            verb = "GET";
            resourceType = "colls";
            resourceLink = string.Format("dbs/{0}/colls", databaseId);
            resourceId = (idBased) ? string.Format("dbs/{0}", databaseId) : databaseId.ToLowerInvariant();

            authHeader = GenerateMasterKeyAuthorizationSignature(verb, resourceId, resourceType, masterKey, "master", "1.0");

            client.DefaultRequestHeaders.Remove("authorization");
            client.DefaultRequestHeaders.Add("authorization", authHeader);

            response = client.GetStringAsync(new Uri(baseUri, resourceLink)).Result;
            
            Console.WriteLine(response);
            Console.ReadKey();

            //GET a collections
            verb = "GET";
            resourceType = "colls";
            resourceLink = string.Format("dbs/{0}/colls/{1}", databaseId, collectionId);
            resourceId = (idBased) ? resourceLink : collectionId.ToLowerInvariant();

            authHeader = GenerateMasterKeyAuthorizationSignature(verb, resourceId, resourceType, masterKey, "master", "1.0");

            client.DefaultRequestHeaders.Remove("authorization");
            client.DefaultRequestHeaders.Add("authorization", authHeader);

            response = client.GetStringAsync(new Uri(baseUri, resourceLink)).Result;
            
            Console.WriteLine(response);
            Console.ReadKey();

            //LIST all documents in a collection
            verb = "GET";
            resourceType = "docs";
            resourceLink = string.Format("dbs/{0}/colls/{1}/docs", databaseId, collectionId);
            resourceId = (idBased) ? string.Format("dbs/{0}/colls/{1}", databaseId, collectionId) : collectionId.ToLowerInvariant();

            authHeader = GenerateMasterKeyAuthorizationSignature(verb, resourceId, resourceType, masterKey, "master", "1.0");

            client.DefaultRequestHeaders.Remove("authorization");
            client.DefaultRequestHeaders.Add("authorization", authHeader);

            response = client.GetStringAsync(new Uri(baseUri, resourceLink)).Result;
            
            Console.WriteLine(response);
            Console.ReadKey();

            //GET a document
            verb = "GET";
            resourceType = "docs";
            resourceLink = string.Format("dbs/{0}/colls/{1}/docs/{2}", databaseId, collectionId, documentId);
            resourceId = (idBased) ? resourceLink : documentId.ToLowerInvariant();

            authHeader = GenerateMasterKeyAuthorizationSignature(verb, resourceId, resourceType, masterKey, "master", "1.0");

            client.DefaultRequestHeaders.Remove("authorization");
            client.DefaultRequestHeaders.Add("authorization", authHeader);

            response = client.GetStringAsync(new Uri(baseUri, resourceLink)).Result;
            
            Console.WriteLine(response);
            Console.ReadKey();

            //EXECUTE a query
            verb = "POST";
            resourceType = "docs";
            resourceLink = string.Format("dbs/{0}/colls/{1}/docs", databaseId, collectionId);
            resourceId = (idBased) ? string.Format("dbs/{0}/colls/{1}", databaseId, collectionId) : collectionId.ToLowerInvariant();

            authHeader = GenerateMasterKeyAuthorizationSignature(verb, resourceId, resourceType, masterKey, "master", "1.0");

            client.DefaultRequestHeaders.Remove("authorization");
            client.DefaultRequestHeaders.Add("authorization", authHeader);
            client.DefaultRequestHeaders.Add("x-ms-documentdb-isquery", "True");
            
            var qry = new SqlQuerySpec { query = "SELECT * FROM root" };
            var r = client.PostWithNoCharSetAsync(new Uri(baseUri, resourceLink), qry).Result;

            Console.WriteLine(r.Content.ToString());
        }
        private static string GenerateMasterKeyAuthorizationSignature(string verb, string resourceId, string resourceType, string key, string keyType, string tokenVersion)
        {
            var hmacSha256 = new System.Security.Cryptography.HMACSHA256 { Key = Convert.FromBase64String(key) };

            string payLoad = string.Format(System.Globalization.CultureInfo.InvariantCulture, "{0}\n{1}\n{2}\n{3}\n{4}\n",
                    verb.ToLowerInvariant(),
                    resourceType.ToLowerInvariant(),
                    resourceId,
                    utc_date.ToLowerInvariant(),
                    ""
            );

            byte[] hashPayLoad = hmacSha256.ComputeHash(System.Text.Encoding.UTF8.GetBytes(payLoad));
            string signature = Convert.ToBase64String(hashPayLoad);

            return System.Web.HttpUtility.UrlEncode(String.Format(System.Globalization.CultureInfo.InvariantCulture, "type={0}&ver={1}&sig={2}",
                keyType,
                tokenVersion,
                signature));
        }
    }
}