SharePoint 2013 REST Services: Downloading a file and working with Json via the HttpClient

I was recently asked about how you would find and download a file using the HttpClient and REST.  I decided to try and accomplish the task in a good old fashion Console Application using the standard .NET libraries instead of the Windows Store this time and realized that even with my past experience and previous code to work from this was no small task and it was only with help from the three following sites I was able to come up with the code below. The lack of the Json classes in the Windows Store libraries makes working with REST responses far more involved, though a bit easier to leverage once you have all the pieces in place when working with a standard .NET application:

Json Serialization Tutorial:

http://www.codeproject.com/Articles/272335/JSON-Serialization-and-Deserialization-in-ASP-NET

Derive .NET classes for serialization from raw Json data:

http://json2csharp.com/

View Json Data in a structure format:

http://jsonviewer.stack.hu/

Once you get your Json responses to your REST API calls you need to take a look at them and create classes to feed to the JsonSerializer.  This leaves you with objects that perfectly mirror the Json data structure as you would view it in the jsonviewer for extracting data.   Once you have all that it’s pretty easy to call the REST API and retrieve the data you need to download files.

Of coarse, the Microsoft.SharePoint.Client library could do the same task in a fraction of the time, but I am often asked how to work with the REST services without using those libraries.

The CODE:

    public class JsonHelper
    {
        /// JSON Serialization
        public static string JsonSerializer<T>(T t)
        {
            DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
            MemoryStream ms = new MemoryStream();
            ser.WriteObject(ms, t);
            string jsonString = Encoding.UTF8.GetString(ms.ToArray());
            ms.Close();
            return jsonString;
        }
        /// JSON Deserialization
        public static T JsonDeserialize<T>(string jsonString)
        {
            DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
            MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonString));
            T obj = (T)ser.ReadObject(ms);
            return obj;
        }
    }

    //Custom Json Classes
    public class RootObject
    {
        public D d { get; set; }
    }
    public class D
    {
        public GetContextWebInformation GetContextWebInformation { get; set; }
        public List<Result> results { get; set; }
    }
    public class GetContextWebInformation
    {
        public int FormDigestTimeoutSeconds { get; set; }
        public string FormDigestValue { get; set; }
        public string LibraryVersion { get; set; }
        public string SiteFullUrl { get; set; }
        public string WebFullUrl { get; set; }
    }
    public class Result
    {
        public ContentType ContentType { get; set; }
        public string EncodedAbsUrl { get; set; }
        public string FileLeafRef { get; set; }
        public Folder Folder { get; set; }
        public int FileSystemObjectType { get; set; }
        public int Id { get; set; }
        public string ContentTypeId { get; set; }
        public string Title { get; set; }
        public int? ImageWidth { get; set; }
        public int? ImageHeight { get; set; }
        public string ImageCreateDate { get; set; }
        public object Description { get; set; }
        public object Keywords { get; set; }
        public string OData__dlc_DocId { get; set; }
        public int ID { get; set; }
        public string Created { get; set; }
        public int AuthorId { get; set; }
        public string Modified { get; set; }
        public int EditorId { get; set; }
        public object OData__CopySource { get; set; }
        public int? CheckoutUserId { get; set; }
        public string OData__UIVersionString { get; set; }
        public string GUID { get; set; }
    }

    class Program
    {
        static void Main()
        {

            string url = "https://sharepoint.site/";
            string filename = "2010-07-23 13.32.22.jpg"; ;
            string digest = "";
            HttpClient client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true });
            client.BaseAddress = new System.Uri(url);
            string cmd = "_api/contextinfo";
            client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
            client.DefaultRequestHeaders.Add("ContentType", "application/json");
            client.DefaultRequestHeaders.Add("ContentLength", "0");
            StringContent httpContent = new StringContent("");
            HttpResponseMessage response = client.PostAsync(cmd, httpContent).Result;
            if (response.IsSuccessStatusCode)
            {
                string content = response.Content.ReadAsStringAsync().Result;
                RootObject sp = JsonHelper.JsonDeserialize<RootObject>(content);
                digest = sp.d.GetContextWebInformation.FormDigestValue;
            }
            client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true });
            client.BaseAddress = new System.Uri(url);
            client.DefaultRequestHeaders.Clear();
            client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
            client.DefaultRequestHeaders.Add("X-RequestDigest", digest);
            client.DefaultRequestHeaders.Add("X-HTTP-Method", "GET");
            string uri = "_api/web/lists/GetByTitle('Your Pictures')/Items?$select=ID,FileLeafRef,EncodedAbsUrl&$filter=FileLeafRef eq '" + filename + "'";
            HttpResponseMessage response2 = client.GetAsync(uri).Result;
            response2.EnsureSuccessStatusCode();
            if (response2.IsSuccessStatusCode)
            {
                string listItems = response2.Content.ReadAsStringAsync().Result;
                RootObject sp = JsonHelper.JsonDeserialize<RootObject>(listItems);
                foreach (Result result in sp.d.results)
                {
                    MemoryStream stream = (MemoryStream)client.GetAsync(result.EncodedAbsUrl).Result.Content.ReadAsStreamAsync().Result;
                    using (FileStream fileStream = System.IO.File.Create(@"C:\" + result.FileLeafRef))
                    {
                        stream.WriteTo(fileStream);
                    }
                }
            }
            else
            {
                var content = response.Content.ReadAsStringAsync();
            }
        }
    }
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SharePoint 2013 REST Services using C# and the HttpClient (for Windows Store Apps)

SharePoint Web Services have come a long way in the last few versions.  I have spent a lot of time working with the SharePoint Object Model And recently started to use the Client Object Model which are both wonderful libraries with great documentation and numerous articles about them.

However, if you have delved into mobile app development recently you will realize that Windows Store projects only give a very specific subset of the core .NET libraries and that Exchange Web Services and the SharePoint Client libraries and many others are not available.  Now this does introduce some difficulty but in SharePoint 2013 REST services will allow you to accomplish almost any task in SharePoint.  The problem is that Microsoft or the development community has decided that any of us working with REST services directly will need to use JavaScript, at least if we want any examples of what these requests would look like.  While I do not mind doing minor tasks in Jscript I vastly prefer C# for doing larger applications and after doing dozens of searches, reading over a hundred articles and posts, I finally broke down and reverse engineered some Jscript examples and massively reworked what few C# examples existed for SharePoint REST.

I will be showing four main things in this post.  How to create a digest, which is used in the headers of any REST query passed from the HttpClient for authentication.  I will demonstrate how to get a list of items and how to work with the Json Objects using only native Windows Store libraries.  I will demonstrate a file upload and finally how to create a new list item with a lookup column.

The Examples:

Creating your digest:

String retVal = "";
try
{
string url = "https://YourSite.com/";
HttpClient client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true });
client.BaseAddress = new System.Uri(url);
string cmd = "_api/contextinfo";

client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
client.DefaultRequestHeaders.Add("ContentType", "application/json");
client.DefaultRequestHeaders.Add("ContentLength", "0");
StringContent httpContent = new StringContent("");
var response = client.PostAsync(cmd, httpContent).Result;
if (response.IsSuccessStatusCode)
{
string content = response.Content.ReadAsStringAsync().Result;
JsonObject val = JsonValue.Parse(content).GetObject();
JsonObject d = val.GetNamedObject("d");
JsonObject wi = d.GetNamedObject("GetContextWebInformation");
retVal = wi.GetNamedString("FormDigestValue");
}
}
catch
{ }
return retVal;

Getting a list of items

In this examples and all that follow the object digest would be passed from the return in the function above:
string url = "https://YourSite.com/Subsite/";
HttpClient client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true });
client.BaseAddress = new System.Uri(url);
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
client.DefaultRequestHeaders.Add("X-RequestDigest", digest);
client.DefaultRequestHeaders.Add("X-HTTP-Method", "POST");
StringContent strContent = new StringContent("");
HttpResponseMessage response = await client.PostAsync("_api/web/lists/GetByTitle('Your List Title')/GetItems(query=@v1)?@v1={'ViewXml':''}", strContent);
response.EnsureSuccessStatusCode();
if (response.IsSuccessStatusCode)
{
var content = response.Content.ReadAsStringAsync();
JsonObject d = JsonValue.Parse(content.Result).GetObject();
JsonObject results = d["d"].GetObject();
JsonArray jobs = results["results"].GetArray();
foreach (JsonValue job in jobs)
{
JobBox.Items.Add(job.GetObject()["Job"].GetObject().GetNamedString("Label"));
}
}
else
{
var content = response.Content.ReadAsStringAsync();
}

Upload a File

FileOpenPicker picker = new FileOpenPicker();
picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
picker.ViewMode = PickerViewMode.Thumbnail;
// Filter to include a sample subset of file types.
picker.FileTypeFilter.Clear();
picker.FileTypeFilter.Add(".bmp");
picker.FileTypeFilter.Add(".png");
picker.FileTypeFilter.Add(".jpeg");
picker.FileTypeFilter.Add(".jpg");
// Open the file picker.
StorageFile path = await picker.PickSingleFileAsync();
if (path != null)
{
string url = "https://YourSite.com/Subsite/";
HttpClient client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true });
client.BaseAddress = new System.Uri(url);
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
client.DefaultRequestHeaders.Add("X-RequestDigest", digest);
client.DefaultRequestHeaders.Add("X-HTTP-Method", "POST");
client.DefaultRequestHeaders.Add("binaryStringRequestBody", "true");
IRandomAccessStream fileStream = await path.OpenAsync(FileAccessMode.Read);
var reader = new DataReader(fileStream.GetInputStreamAt(0));
await reader.LoadAsync((uint)fileStream.Size);
Byte[] content = new byte[fileStream.Size];
reader.ReadBytes(content);
ByteArrayContent file = new ByteArrayContent(content);
HttpResponseMessage response = await client.PostAsync("_api/web/lists/getByTitle(@TargetLibrary)/RootFolder/Files/add(url=@TargetFileName,overwrite='true')?@TargetLibrary='Project Photos'&@TargetFileName='TestUpload.jpg'", file);
response.EnsureSuccessStatusCode();
if (response.IsSuccessStatusCode)
{ }
}

Create List Item with a multivalue lookup field

string url = "https://YourSite.com/Subsite/";
HttpClient client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true });
client.BaseAddress = new System.Uri(url);
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Add("X-RequestDigest", digest);
client.DefaultRequestHeaders.Add("X-HTTP-Method", "POST");
HttpContent content = new StringContent("{ '__metadata': { 'type': 'SP.Data.ReportListItem' }, 'Title': 'NewTitle', 'PhotosId': { 'results': [2] }, 'Details': 'Another successful day!' }");
content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
content.Headers.ContentType.Parameters.Add(new NameValueHeaderValue("odata", "verbose"));
HttpResponseMessage response = await client.PostAsync("_api/web/lists/GetByTitle('Report')/items", content);
response.EnsureSuccessStatusCode();
if (response.IsSuccessStatusCode)
{
}
else
{
}

The Json for lookups is a bit tricky.  You have to specify the ID of the item in the other list or of the user if its a people picker.  Also the column name here has ‘Id’ appended onto the end of it.  If the column already ends in Id then you will end up with Id twice.  In a multivalue scenario the Json looks like this:

‘PhotosId’: { ‘results’: [2,3] }

Singe Value:

‘PhotosId’: 2

Also you need to figure out the type represented here:

‘SP.Data.ReportListItem’

This is broken up as SP . Data . YourListName ListItem.  I have not tested this with Lists that have a space in their titles so I would test that or avoid spaces.

Updating a list item by ID

client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true });
client.BaseAddress = new System.Uri(url);
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Add("X-RequestDigest", digest);
client.DefaultRequestHeaders.Add("X-HTTP-Method", "MERGE");
client.DefaultRequestHeaders.Add("IF-MATCH", "*");
HttpContent strContent = new StringContent(String.Concat("{ '__metadata': { 'type': 'SP.List' }, 'Title': '", filename, "' }"));
strContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
strContent.Headers.ContentType.Parameters.Add(new NameValueHeaderValue("odata", "verbose"));
HttpResponseMessage updateResponse = await client.PostAsync(String.Concat("_api/web/lists/GetByTitle('Project Photos')/Items(", id, ")"), strContent);
updateResponse.EnsureSuccessStatusCode();
if (updateResponse.IsSuccessStatusCode)
{}

Hopefully everyone finds this article helpful.  I do not wish to spend the rest of my days writing JavaScript every time I need to work on applications for mobility and I assume that at least a few other developers share my sentiments.