How can I post JSON to an ASP.NET MVC controller action?
sample scenario
An external authentication system requires JSON be posted to it. I would like to capture the user's credentials on my site and forward them as JSON to the authentication site. Redirects are not an option.
So we'll use http://www.example.com/ExtAuth/Login as our fictitious external authentication endpoint.
ExtAuth will expect us to post a JSON string representing an object with two properties: User, and Password.
ExtAuth will return a JSON string representing an object with two properties: Status, and Message.
The key to making this whole thing work is the extRequest.ContentType. It MUST be set to application/json.
I'll leave proper error handling as an exercise to the user.
<HttpPost>
<AllowAnonymous>
Public Function Login(ByVal model As LoginModel) As ActionResult
Dim authEndpointUrl As String = "http://www.example.com/ExtAuth/Login"
Dim result As String = String.Empty ' this will hold the JSON returned from ExtAuth
Dim resultModel As LoginResult = Nothing ' The deserialized form of the result JSON
Dim data As String = String.Empty ' the serialized representation of our login data
Dim extRequest As HttpWebRequest = WebRequest.CreateHttp(authEndpointUrl)
extRequest.Method = "POST"
extRequest.ContentType = "application/json"
data = Newtonsoft.Json.JsonConvert.SerializeObject(model)
Using writer As StreamWriter = New StreamWriter(extRequest.GetRequestStream)
writer.Write(data)
End Using
Using extResponse As HttpWebResponse = extRequest.GetResponse
Using reader As StreamReader = New StreamReader(extResponse.GetResponseStream)
result = reader.ReadToEnd
End Using
End Using
resultModel = Newtonsoft.Json.JsonConvert.DeserializeObject(Of LoginResult)(result)
ViewData("Status") = resultModel.Status
ViewData("Message") = resultModel.Message
Return View(model)
End Function
This method should work for MVC 3+.
Related
I'm writing code to perform CRUD operations using JavaScript and VB.NET MVC. I'll require a method to send parameters from Controller to the View, but I don't know how to catch the value from the URL.
Following is my controller:
' GET: Bodega/Index/5
Function Edit(ByVal id As Integer, ByVal collection As FormCollection) As ActionResult
Try
Dim constr As String = ConfigurationManager.ConnectionStrings("conexion").ConnectionString
Using con As New SqlConnection(constr)
Using cmd As New SqlCommand("SELECT * FROM bodega WHERE id = #Id")
cmd.Parameters.AddWithValue("#Id", id)
cmd.Connection = con
Dim data As New List(Of Bodega)()
con.Open()
Using sdr As SqlDataReader = cmd.ExecuteReader()
While sdr.Read()
data.Add(New Bodega() With {
.id = Convert.ToInt32(sdr("id")),
.nombre = sdr("nombre").ToString(),
.ubicacion = sdr("ubicacion").ToString(),
.lugar = sdr("lugar").ToString(),
.lat = sdr("lat").ToString(),
.lng = sdr("lng").ToString()
})
End While
End Using
con.Close()
Return View("Index", id)
End Using
End Using
Catch e As Exception
Return RedirectToAction("Index")
End Try
End Function
I'm sending the id to the View via the return statement, but in the view i don't know what command can use.
The URL format is:
localhost/Bodega/Edit/5
I need catch the ID 5. If as possible save into a hidden input or send to a javascript code to load the data pre-load for the inputs.
In the Edit view that is calling the Edit action, make sure that the route value is called id so that it can bind to the id parameter. Also, it doesn’t seem like you’re using the FormCollection parameter. And did you mean to pass the new Bodega instance you’re creating over to the view instead of the id? I’m guessing that you are looking up a bodega to be edited in an edit view?
I have some strange problem. I am using Microsoft.AspNet.WebApi.Client.5.2.3 for simple .NET client for API. I want to post some data to API. I am using PostAsJsonAsync method for it.
using (var client = new HttpClient())
{
var adress = new Uri("http://localhost:28906/v1/things?access_token=SOMETOKEN");
var result = await client.PostAsJsonAsync(adress, new ThingModel() { Name = "test"});
}
When I am sending request, my uri is transformed from "http://localhost:28906/v1/things?access_token=SOMETOKEN" to "http://localhost:28906/v1/things/?access_token=SOMETOKEN" ( '/' is inserted before '?'). And request becomes wrong. How can I overcome this? In fact, how can I pass query string and json body?
Is there any reason that the Breeze Web API implementation of the response to any metadata requests returns a string instead of a JSON object?
Sending metadata as text adds a lot of overhead over the network (due " encoding) and on clientside due manual JSON.parse.
I think that your controller can simply return the Metadata as JSON by specifying the contentType header:
i.e.
[HttpGet]
public HttpResponseMessage Metadata()
{
var result = new HttpResponseMessage { Content = new StringContent(_contextProvider.Metadata())};
result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
return result;
}
As of v 1.2.7, the BreezeController attribute now does this automatically.... and thanks for the idea.
This is a follow-up to this post: New at MVC 4 Web API Confused about HTTPRequestMessage
Here is a summary of what I am trying to do: There is a web site that I want to interface with via MVC 4 Web API. At the site, users can log in with a user name and password, then go to a link called ‘Raw Data’ to query data from the site.
On the ‘Raw Data’ page, there is a dropdown list for ‘Device’, a text box for ‘From’ date, and a text box for ‘To’ date. Given these three parameters, the user can click the ‘Get Data’ button, and return a table of data to the page. What I have to do, is host a service on Azure that will programmatically provide values for these three parameters to the site, and return a CSV file from the site to Azure storage.
The company that hosts the site has provided documentation to programmatically interface with the site to retrieve this raw data. The document describes how requests are to be made against their cloud service. Requests must be authenticated using a custom HTTP authentication scheme. Here is how the authentication scheme works:
Calculate an MD5 hash from the user password.
Append the request line to the end of the value from step one.
Append the date header to the end of the value in step two.
Append the message body (if any) to the end of the value in step 3.
Calculate MD5 hash over the resulting value from step 4.
Append the value from step 5 to the user email using the “:” character as a delimiter.
Calculate Base64 over the value from step 6.
The code that I am going to list was done in Visual Studio 2012, C#, .NET Framework 4.5. All of the code in this post is in my 'FileDownloadController.cs' Controller class. The ‘getMd5Hash’ function takes a string, and returns an MD5 hash:
//Create MD5 Hash: Hash an input string and return the hash as a 32 character hexadecimal string.
static string getMd5Hash(string input)
{
// Create a new instance of the MD5CryptoServiceProvider object.
MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();
// Convert the input string to a byte array and compute the hash.
byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input));
// Create a new Stringbuilder to collect the bytes
// and create a string.
StringBuilder sBuilder = new StringBuilder();
// Loop through each byte of the hashed data
// and format each one as a hexadecimal string.
for (int i = 0; i < data.Length; i++)
{
sBuilder.Append(data[i].ToString("x2"));
}
// Return the hexadecimal string.
return sBuilder.ToString();
}
This function takes a string, and returns BASE64:
//Convert to Base64
static string EncodeTo64(string input)
{
byte[] str1Byte = System.Text.Encoding.ASCII.GetBytes(input);
String plaintext = Convert.ToBase64String(str1Byte);
return plaintext;
}
The next function creates an HTTPClient, makes an HTTPRequestMessage, and returns the authorization. Note: The following is the URI that was returned from Fiddler when data was returned from the ‘Raw Data’ page: GET /rawdata/exportRawDataFromAPI/?devid=3188&fromDate=01-24-2013&toDate=01-25-2013 HTTP/1.1
Let me first walk through what is happening with this function:
The ‘WebSiteAuthorization’ function takes a ‘deviceID’, a ‘fromDate’, a ‘toDate’ and a ‘password’.
Next, I have three variables declared. I’m not clear on whether or not I need a ‘message body’, but I have a generic version of this set up. The other two variables hold the beginning and end of the URI.
I have a variable named ‘dateHeader’, which holds the data header.
Next, I attempt to create an HTTPClient, assign the URI with parameters to it, and then assign ‘application/json’ as the media type. I’m still not very clear on how this should be structured.
In the next step, the authorization is created, per the requirements of the API documentation, and then the result is returned.
public static string WebSiteAuthorization(Int32 deviceid, string fromDate, string toDate, string email, string password)
{
var messagebody = "messagebody"; // TODO: ??????????? Message body
var uriAddress = "GET/rawdata/exportRawDataFromAPI/?devid=";
var uriAddressSuffix = "HTTP/1.1";
//create a date header
DateTime dateHeader = DateTime.Today;
dateHeader.ToUniversalTime();
//create the HttpClient, and its BaseAddress
HttpClient ServiceHttpClient = new HttpClient();
ServiceHttpClient.BaseAddress = new Uri(uriAddress + deviceid.ToString() + " fromDate" + fromDate.ToString() + " toDate" + toDate.ToString() + uriAddressSuffix);
ServiceHttpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
//create the authorization string
string authorizationString = getMd5Hash(password);
authorizationString = authorizationString + ServiceHttpClient + dateHeader + messagebody;
authorizationString = email + getMd5Hash(authorizationString);
authorizationString = EncodeTo64(authorizationString);
return authorizationString;
}
I haven’t tested this on Azure yet. I haven't completed the code that gets the file. One thing I know I need to do is to determine the correct way to create an HttpRequestMessage and use HttpClient to send it. In the documentation that I've read, and the examples that I've looked at, the following code fragments appear to be possible approaches to this:
Var serverAddress = http://my.website.com/;
//Create the http client, and give it the ‘serverAddress’:
Using(var httpClient = new HttpClient()
{BaseAddress = new Uri(serverAddress)))
Var requestMessage = new HttpRequestMessage();
Var objectcontent = requestMessage.CreateContent(base64Message, MediaTypeHeaderValue.Parse (“application/json”)
or----
var formatters = new MediaTypeFormatter[] { new jsonMediaTypeFormatter() };
HttpRequestMessage<string> request = new HttpRequestMessage<string>
("something", HttpMethod.Post, new Uri("http://my.website.com/"), formatters);
request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
var httpClient = new HttpClient();
var response = httpClient.SendAsync(request);
or------
Client = new HttpClient();
var request = new HttpRequestMessage
{
RequestUri = "http://my.website.com/",
Method = HttpMethod.Post,
Content = new StringContent("ur message")
};
I'm not sure which approach to take with this part of the code.
Thank you for your help.
Read this step by step tutorial to understand the basic.
Having a string containing the following raw Json data (simplified for the sake of the question):
var MyString = "{ 'val': 'apple' }";
How can I create a JsonResult object representing MyString?
I tried to use the Json(object) method. but it handles the raw json data as an string -logically :P-. So the returned HTTP response looks like:
"{ 'val': 'apple' }"
instead of the given raw Json Data:
{ 'val': 'apple' }
this is what I want to achieve:
The Json() method on Controller is actually a helper method that creates a new JsonResult. If we look at the source code for this class*, we can see that it's not really doing that much -- just setting the content type to application/json, serializing your data object using a JavaScriptSerializer, and writing it the resulting string.. You can duplicate this behavior (minus the serialization, since you've already done that) by returning a ContentResult from your controller instead.
public ActionResult JsonData(int id) {
var jsonStringFromSomewhere = "{ 'val': 'apple' }";
// Content() creates a ContentResult just as Json() creates a JsonResult
return Content(jsonStringFromSomewhere, "application/json");
}
* Starting in MVC2, JsonResult also throws an exception if the user is making an HTTP GET request (as opposed to say a POST). Allowing users to retrieve JSON using an HTTP GET has security implications which you should be aware of before you permit this in your own app.
The way I have generated json data from a string is by using JavaScriptResult in the controller:
public JavaScriptResult jsonList( string jsonString)
{
jsonString = "var jsonobject = new Array(" + jsonString + ");";
return JavaScript(jsonString)
}
Then when you request pass the json string to that action in your controller, the result will be a file with javascript headers.
I think you can use the JavaScriptSerializer class for this
var js = new System.Web.Script.Serialization.JavaScriptSerializer();
var jsonObject = js.Deserialize("{ 'val': 'apple' }", typeof(object));