从 HTTP 请求接收 JSON 数据

Question

I have a web request that is working properly, but it is just returning the status OK, but I need the object I am asking for it to return. I am not sure how to get the json value I am requesting. I am new to using the object HttpClient, is there a property I am missing out on? I really need the returning object. Thanks for any help

Making the call - runs fine returns the status OK.

HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Accept
  .Add(new MediaTypeWithQualityHeaderValue("application/json"));
var responseMsg = client.GetAsync(string.Format("http://localhost:5057/api/Photo")).Result;

The api get method

//Cut out alot of code but you get the idea
public string Get()
{
    return JsonConvert.SerializeObject(returnedPhoto);
}

Answer 1

If you are referring to the System.Net.HttpClient in .NET 4.5, you can get the content returned by GetAsync using the HttpResponseMessage.Content property as an HttpContent -derived object. You can then read the contents to a string using the HttpContent.ReadAsStringAsync method or as a stream using the ReadAsStreamAsync method.

The HttpClient class documentation includes this example:

  HttpClient client = new HttpClient();
  HttpResponseMessage response = await client.GetAsync("http://www.contoso.com/");
  response.EnsureSuccessStatusCode();
  string responseBody = await response.Content.ReadAsStringAsync();

Answer 2

Building on @Panagiotis Kanavos ' answer, here's a working method as example which will also return the response as an object instead of a string:

using System.Text;
using System.Net.Http;
using System.Threading.Tasks;
using Newtonsoft.Json; // Nuget Package

public static async Task<object> PostCallAPI(string url, object jsonObject)
{
    try
    {
        using (HttpClient client = new HttpClient())
        {
            var content = new StringContent(jsonObject.ToString(), Encoding.UTF8, "application/json");
            var response = await client.PostAsync(url, content);
            if (response != null)
            {
                var jsonString = await response.Content.ReadAsStringAsync();
                return JsonConvert.DeserializeObject<object>(jsonString);
            }
        }
    }
    catch (Exception ex)
    {
        myCustomLogger.LogException(ex);
    }
    return null;
}

Keep in mind that this is only an example and that you'd probably would like to use HttpClient as a shared instance instead of using it in a using-clause.

Answer 3

Install this nuget package from Microsoft System.Net.Http.Json . It contains extension methods.

Then add using System.Net.Http.Json

Now, you'll be able to see these methods:

So you can now do this:

await httpClient.GetFromJsonAsync<IList<WeatherForecast>>("weatherforecast");

Source: https://www.stevejgordon.co.uk/sending-and-receiving-json-using-httpclient-with-system-net-http-json

Answer 4

I think the shortest way is:

var client = new HttpClient();
string reqUrl = $"http://myhost.mydomain.com/api/products/{ProdId}";
var prodResp = await client.GetAsync(reqUrl);
if (!prodResp.IsSuccessStatusCode){
    FailRequirement();
}
var prods = await prodResp.Content.ReadAsAsync<Products>();

Answer 5

It's working fine for me by the following way -

public async Task<object> TestMethod(TestModel model)
    {
        try
        {
            var apicallObject = new
            {
                Id= model.Id,
                name= model.Name
            };

            if (apicallObject != null)
            {
                var bodyContent = JsonConvert.SerializeObject(apicallObject);
                using (HttpClient client = new HttpClient())
                {
                    var content = new StringContent(bodyContent.ToString(), Encoding.UTF8, "application/json");
                    content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
                    client.DefaultRequestHeaders.Add("access-token", _token); // _token = access token
                    var response = await client.PostAsync(_url, content); // _url =api endpoint url
                    if (response != null)
                    {
                        var jsonString = await response.Content.ReadAsStringAsync();

                        try
                        {
                            var result = JsonConvert.DeserializeObject<TestModel2>(jsonString); // TestModel2 = deserialize object
                        }
                        catch (Exception e){
                            //msg
                            throw e;
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
        return null;
    }

Answer 6

What I normally do, similar to answer one:

var response = await httpClient.GetAsync(completeURL); // http://192.168.0.1:915/api/Controller/Object

if (response.IsSuccessStatusCode == true)
    {
        string res = await response.Content.ReadAsStringAsync();
        var content = Json.Deserialize<Model>(res);

// do whatever you need with the JSON which is in 'content'
// ex: int id = content.Id;

        Navigate();
        return true;
    }
    else
    {
        await JSRuntime.Current.InvokeAsync<string>("alert", "Warning, the credentials you have entered are incorrect.");
        return false;
    }

Where 'model' is your C# model class.

Answer 7

The code below is to access your HttpResponseMessage and extract your response from HttpContent.

string result = ret.Result.Content.ReadAsStringAsync().Result;

Convert your json in a structure according with your business In my case BatchPDF is a complex object that it is being populated by result variable.

BatchPDF batchJson = JsonConvert.DeserializeObject<BatchPDF>(result);

return batchJson;