3

I've create WebAPI in .net (my first). Using this api to get object from db, query db etc is easy for me. Nothing new

But I'm wondering how to save an object using this webapi ?

I have a clinet application (tablet, phone, PC) that communicates with my webapi. From my application there is an possibility to save a user news. Now I need to save it in db. I use Azure SQL. Now how can I pass this object to API so I can save it ?

For my application I use C#/XAML For my WebAPI I use .NET

I'm tring with this code:

HttpClient httpClient = new HttpClient();
        String u = this.apiUrl + "sd/Localization/insert";
        Uri uri = new Uri(u);
        HttpRequestMessage httpRequestMessage = new HttpRequestMessage(HttpMethod.Post, uri);

But I don't know how to send object ? Should I serialize it ? If yes how to send it via post.

// UPDATE

I've constructed this

        HttpClient httpClient = new HttpClient();
        String u = this.apiUrl + "sd/Localization/insert";
        Uri uri = new Uri(u);
        HttpRequestMessage httpRequestMessage = new HttpRequestMessage(HttpMethod.Post, uri);
        httpRequestMessage.Content = new StringContent("{'Name':'Foo', 'Surname':'Bar'}");
        await httpClient.PostAsync(uri, httpRequestMessage.Content);

But in my API the variable is null

This is code from my api

    // POST sd/Localization/insert
    public void Post(string test)
    {
        Console.WriteLine(test);
    }

The "test" variable is null. What am I doing wrong ?

// UPDATE 2

        using (HttpClient httpClient = new HttpClient())
        {
            String u = this.apiUrl + "sd/Localization/insert";
            Uri uri = new Uri(u);
            HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, uri)
            {
                Method = HttpMethod.Post,
                Content = new StringContent("my own test string")
            };

            await httpClient.PostAsync(uri, request.Content);
        }

Routing config

public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "sd/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
        );
    }
}

after all your answers I've created this but still I get null on param in my api. Where is the mistake ?

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8 Answers 8

Reset to default
6

WebAPI is really good at parsing data sent to it and converting it to .NET objects.

I am not used to using a C# client with WebAPI, but I'd try the following:

var client = new HttpClient();
client.PostAsJsonAsync<YourObjectType>("uri", yourObject);

Note: You need to use System.Net.Http (from assembly with the same name) as well as System.Net.Http.Formatting (also from assembly with the same name) for this.

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7 Comments

there is no such method like PostAsJsonAsync. I found only PostAsync. I can't set there my object. The second param is HttpContent. Is this the same what you want to show me ?
Fixus, Are you using the RC version of ASP.NET MVC 4 or an older version of the Web API ?
Im using VS RC 2012 and Ive created project with .Net Framework 4.5
Make sure you have added references to the two assemblies I have mentioned - as well as using clauses. But you can use PostAsync just as well, it's just a bit more verbose: client.PostAsync("uri", yourobject, new JsonMediaTypeFormatter());
I notice he's tagged his post with windows-8 and windows-runtime, which implies that he's writing a "Windows Store" (formerly "Metro") app, although he's not made that explicitly clear. If that's so, that might explain why he doesn't have these methods - as far as I can tell, the WinRT version of .NET 4.5 doesn't include the HttpClientExtensions class (usually in System.Net.Http.Formatting.dll) that defines PostAsJsonAsync (and VS won't let you add a reference to libraries from the main .NET class library).
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3

The HttpRequestMessage class has a property named Content which is type of HttpContent (an abstract class). You can set the request body there. For example, you can set the JSON content there and then send it to the API:

HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, uri) { 

    Content = new StringContent("{'Name':'Foo', 'Surname':'Bar'}")
};

You can also use the formatting feature and supply your CLR object to ObjectContent and delegate the serialization to the Formatter.

There are lots of samples on HttpClient and Web API here: http://blogs.msdn.com/b/henrikn/archive/2012/07/20/asp-net-web-api-sample-on-codeplex.aspx

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3 Comments

Thanks. now I know how to set content but after send I get null on it. I've updated my code. Would be cool if you look at it :)
@Fixus try to use FromBody attribute: public void Post([FromBody]string test).
when I add this the method isn`t invoked. i mean the Post method in my API. When I delete it is invoked but the test variable is null
3

Assuming you have an action method on your web API controller that supports a POST operation that is similiar to:

[HttpPost()]
public HttpResponseMessage Post(YourObjectType value)
{
    try
    {

        var result      = this.Repository.Add(value);

        var response = this.Request.CreateResponse<YourObjectType>(HttpStatusCode.Created, result);

        if (result != null)
        {
            var uriString               = this.Url.Route(null, new { id = result.Id });
            response.Headers.Location   = new Uri(this.Request.RequestUri, new Uri(uriString, UriKind.Relative));
        }

        return response;
    }
    catch (ArgumentNullException argumentNullException)
    {
        throw new HttpResponseException(
            new HttpResponseMessage(HttpStatusCode.BadRequest)
            {
                ReasonPhrase    = argumentNullException.Message.Replace(Environment.NewLine, String.Empty)
            }
        );
    }
}

You can use the HttpClient to serialize your object to JSON and POST the content to you controller method:

using (var client = new HttpClient())
{
    client.BaseAddress  = baseAddress;
    client.Timeout      = timeout;

    using (var response = client.PostAsJsonAsync<YourObjectType>("controller_name", yourObject).Result)
    {
        if (!response.IsSuccessStatusCode)
        {
            // throw an appropriate exception
        }

        result  = response.Content.ReadAsAsync<YourObjectType>().Result;
    }
}

I would also recommend taking a look at Creating a Web API that Supports CRUD Operations, which covers the scenarios you are describing, specifically the Creating a Resource section.

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7 Comments

Thanks for advice. Ive updated my post. Could you look on it ? I think Im close :)
I've updated my post and added routing configuration. Any tips ? :)
After reading your comment I've checked the routing. I've changed the param of the function name in webapi from "test" to "id". Now in my api the variable gets value "insert" where the url of this post action is // POST sd/Localization/insert public void Post(String id). I still don't get the value that I want but at least this isn't null. Any ideas what am I doing wrong ?
Use the PostAsJsonAsync method instead of building the content explicitly in the request messag, and add your complex type to the controller method as a parmater. The model binding is not translating the request content to a complex type (what you defined in your JSON). You should define a 'User' class with the properties you want to send and use that as the parameter in your controller method in order to have model binding convert the JSON payload into a deserialized object representation.
I dont have PostAsJsonAsync method in HttpClient. I have only PostAsync and I can't set type in it. I wrote about that. Maybe its because I'm writing it in windows 8
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1

I think I found the solution thats why I'm posting this as answer not comment so any later discussion could be grouped.

If I send request like this

using(HttpClient client = new HttpClient()) {
    await client.PostAsync(uri, new StringContent("my own string");
}

Than I can get it in my webapi from

await Request.Content.ReadAsStringAsync();

IMO this is not perfect solution but at least I'm on trace. I see that params from function definitione I can get only if they are in URL even when I send a POST request.

Probably this solution also will work (i didn't check it yet) when I use more complex objects then String.

ANy thoughts from someone. Do you think that this is good solution ?

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3 Comments

Is there a reason you want to send and recieve data as a string instead of a strongly typed object representation?
I dont have PostAsJsonAsync where I can set type. I have PostAsync where I can set only message as a class of HttpContent
This might be really late for your question but I found it today and struggled for quite a few hours. The reason you couldn't post an object to your webapi was because your Model didn't have a default Constructor (in the web api side) once you add an empty default constructor it all works. I will post an answer for posterity
1

I hope this would be what you are looking for.

I created a generic Post that will accept any object and post it
Client Side

public async Task<HttpResponseMessage> Post<T>(string requestUri, T newObject) where T : class
{
  using (var client = new HttpClient())
  {
     client.BaseAddress = this.HttpClientAddress;
     client.DefaultRequestHeaders.Accept.Clear();
     client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
     var content = JsonConvert.SerializeObject(newObject, this.JsonSerializerSettings);
     var clientAsync = await client.PostAsync(requestUri, new StringContent(content, Encoding.UTF8, "application/json"));
     clientAsync.EnsureSuccessStatusCode();

     return clientAsync;
   }
}

the call to this will be as simple as 

public async Task<int> PostPerson(Models.Person person)
{
  //call to the generic post 
  var response = await this.Post("People", person);

  //get the new id from Uri api/People/6 <-- this is generated in the response after successful post
  var st =  response.Headers.Location.Segments[3];

  //do whatever you want with the id
  return response.IsSuccessStatusCode ? JsonConvert.DeserializeObject<int>(st) : 0;
}

Also, you can read the object after the post using ReadAsStringAsync() if your usecase requires so.


Server Side

// POST: api/People
  public IHttpActionResult Post(Models.Person personDto)
    {

        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        var person = new Entities.Person
                     {
                             FirstName = personDto.FirstName,
                             LastName = personDto.LastName,
                             DateOfBirth = personDto.DateOfBirth,
                             PreferedLanguage = personDto.PreferedLanguage

                     };
        _db.Persons.Add(person);
        _db.SaveChanges();
        return CreatedAtRoute("DefaultApi", new { id = person.Id }, personDto);
    }
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0

I'm not familiar with the HttpClient (I believe it's .NET 4.5), but the concepts behind WebAPI are using standard RESTful constructs. If you want to insert an object via WebAPI, you will need to send a POST request to the service. You should put the contents of the object into the BODY of the request.

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1 Comment

how can I set body of my request? I can`t find any samples :(
0

Add empty constructors to your webapi model people. This will save you all the time I just wasted trying to figure out why my object was null. Serialization (and de-serialization i suppose) need default constructors.

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0

This is my way.it's successfully.i hope it's helpful Fisrt:is all library you must have.you can download from nuget

using Newtonsoft.Json; and using Newtonsoft.Json.Linq;

Client :

HttpClient client = new HttpClient();

//this is url to your API server.in local.You must change when u pushlish on real host
Uri uri = new Uri("http://localhost/");
client.BaseAddress = uri;

//declared a JArray to save object 
JArray listvideoFromUser = new JArray();

//sample is video object
VideoModels newvideo = new VideoModels();

//set info to new object..id/name...etc.
newvideo._videoId = txtID.Text.Trim();

//add to jArray
listvideoFromUser.Add(JsonConvert.SerializeObject(newvideo));

//Request to server
//"api/Video/AddNewVideo" is router of API .you must change with your router
HttpResponseMessage response =client.PostAsJsonAsync("api/Video/AddNewVideo", listvideoFromUser).Result;
if (response.IsSuccessStatusCode){
    //show status process
     txtstatus.Text=response.StatusCode.ToString();
}
else{
    //show status process
    txtstatus.Text=response.StatusCode.ToString();
}

Server side: 

[Route("api/Video/AddNewVideo")]
[System.Web.Http.HttpPost]
public HttpResponseMessage AddNewVideo(JArray listvideoFromUser){
    if (listvideoFromUser.Count > 0){
        //DeserializeObject: that object you sent from client to server side. 
        //Note:VideoModels is class object same as model of client side
        VideoModels video = JsonConvert.DeserializeObject<VideoModels>(listvideoFromUser[0].ToString());

        //that is just method to save database
        Datacommons.AddNewVideo(video);

        //show status for client
        HttpResponseMessage response = new HttpResponseMessage { StatusCode = HttpStatusCode.Created };
        return response;
    }
    else{
        HttpResponseMessage response = new HttpResponseMessage { StatusCode = HttpStatusCode.InternalServerError };
        return response;
    }
}

All done !

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