FromBody string parameter is giving null

Question

This is probably something very basic  but I am having trouble figuring out where I am going wrong    I am trying to grab a string from the body of a POST  but  jsonString  only shows as null  I also want to avoid using a model  but maybe this isn t possible  The piece of code that I am hitting with PostMan is this chunk    Route  Edit Test     HttpPost  public void Test int id   FromBody  string jsonString                Maybe it is something I am doing incorrectly with postman  but I have been trying to use   test   as seen in other questions asked about this topic  in the value section of the body - x-www-form-urlencoded section with the key as jsonString and nothing  I have also tried using raw - text and raw - text plain  I get the id so I know the url is correct  Any help with this would be greatly appreciated    PostMan is set up like this currently   POST http   localhost 8000 Edit Test id 111 key   id  value   111 Body - x-www-form-urlencoded key   jsonString  value     test

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Try the below code    Route   test     HttpPost  public async Task Test        using  var reader   new StreamReader Request Body  Encoding UTF8              var textFromBody   await reader ReadToEndAsync

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Finally got it working after 1 hour struggle   This will remove null issue  also gets the JSON key1 s value of value1  in a generic way  no model binding      For a new WebApi 2 application example      Postman  looks exactly  like below     POST    http   localhost 61402 api values    Send  Body          raw             JSON  application json  v                key1      value1        The port 61402 or url  api values above  may be different for you      ValuesController cs   using Newtonsoft Json            POST api values  HttpPost  public object Post  FromBody string jsonString           add reference to Newtonsoft Json         using Newtonsoft Json          jsonString to myJsonObj     var myJsonObj   JsonConvert DeserializeObject lt Dictionary lt string  dynamic gt  gt  jsonString           value1 is myJsonObj key1      var valueOfkey1   myJsonObj  key1         return myJsonObj      All good for now  not sure if model binding to a class is required if I have sub keys  or  may be DeserializeObject on sub key will work

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I just ran into this and was frustrating  My setup  The header was set to Content-Type  application JSON and was passing the info from the body with JSON format  and was reading  FromBody  on the controller  Everything was set up fine and I expect it to work  but the problem was with the JSON sent over  Since it was a complex structure  one of my classes which was defined  Abstract  was not getting initialized and hence the values weren t assigned to the model properly  I removed the abstract keyword and it just worked      One tip  the way I could figure this out was to send data in parts to my controller and check when it becomes null    since it was a complex model I was appending one model at a time to my request params  Hope it helps someone who runs into this stupid issue

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When having   FromBody attribute  the string sent  should  not be a raw string  but rather a JSON string  as it includes the wrapping quotes      test    Based on https   weblog west-wind com posts 2017 Sep 14 Accepting-Raw-Request-Body-Content-in-ASPNET-Core-API-Controllers  Similar answer string value is Empty when using FromBody in asp net web api

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I know this answer is kinda old and there are some very good answers who already solve the problem  In order to expand the issue I d like to mention one more thing that has driven me crazy for the last 4 or 5 hours   It is VERY VERY VERY important that your properties in your model class have the set attribute enabled   This WILL NOT work  parameter still null       Action code     HttpPost  public Weird NOURLAuthenticate  FromBody  Weird form        return form       Model class code    public class Weird       public string UserId  get       public string UserPwd  get       This WILL work      Action code     HttpPost  public Weird NOURLAuthenticate  FromBody  Weird form        return form       Model class code    public class Weird       public string UserId  get  set       public string UserPwd  get  set

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If you don t want need to be tied to a concrete class  you can pass JSON directly to a WebAPI controller  The controller is able to accept the JSON by using the ExpandoObject type  Here is the method example   public void Post  FromBody ExpandoObject json        var keyValuePairs     System Collections Generic IDictionary lt string  object gt  json       Set the Content-Type header to application json and send the JSON as the body  The keyValuePairs object will contain the JSON key value pairs   Or you can have the method accept the incoming JSON as a JObject type  from Newtonsoft JSON library   and by setting it to a dynamic type  you can access the properties by dot notation   public void Post  FromBody JObject  json        dynamic json    json

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After a long nightmare of fiddling with Google and trying out the wrong code in Stack Overflow I discovered changing   FromBody  string model  to   FromBody  object model  does wonders please not i am using  NET 4 0 yes yes i know it s old but

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You are on the right track    On your header set  Content-Type  application x-www-form-urlencoded   The body of the POST request should be  test and nothing else  For unknown variable strings you have to URL encode the value so that way you do not accidentally escape with an input character     See also POST string to ASP NET Web Api application - returns null

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By declaring the jsonString parameter with  FromBody  you tell ASP NET Core to use the input formatter to bind the provided JSON  or XML  to a model  So your test should work  if you provide a simple model class  public class MyModel       public string Key  get  set       Route  Edit Test     HttpPost  public void Test int id   FromBody  MyModel model            model Key         and a sent JSON like        key   value      Of course you can skip the model binding and retrieve the provided data directly by accessing HttpContext Request in the controller  The HttpContext Request Body property gives you the content stream or you can access the form data via HttpContext Request Forms   I personally prefer the model binding because of the type safety

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Referencing Parameter Binding in ASP NET Web API     Using  FromBody       To force Web API to read a simple type from the request body  add the    FromBody  attribute to the parameter    Route  Edit Test     HttpPost  public IHttpActionResult Test int id   FromBody  string jsonString                In this example  Web API will use a media-type formatter to read the   value of jsonString from the request body  Here is an example client   request       POST http   localhost 8000 Edit Test id 111 HTTP 1 1 User-Agent  Fiddler Host  localhost 8000 Content-Type  application json Content-Length  6   test        When a parameter has  FromBody   Web API uses the Content-Type header   to select a formatter  In this example  the content type is    application json  and the request body is a raw JSON string  not a   JSON object     In the above example no model is needed if the data is provided in the correct format in the body   For URL encoded a request would look like this  POST http   localhost 8000 Edit Test id 111 HTTP 1 1 User-Agent  Fiddler Host  localhost 8000 Content-Type  application x-www-form-urlencoded Content-Length  5   test

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The whole day has gone for me to resolve similar issue  You must know that built-in serializor and Newtonsoft work differently  Im my case built-in cannot parse JSON number to System String  But I had no obvious exception or details  just data came as null  I discovered it only when I logged ModelState like that  logger LogInformation   quot ModelState    ModelState IsValid  quot    string messages   string Join  quot    quot   ModelState Values                      SelectMany x   gt  x Errors                       Select x   gt  x ErrorMessage    logger LogInformation   quot ModelMessages    messages  quot     And then I saw specific exception in logs  The JSON value could not be converted to System String  As a fix I did   Install Microsoft AspNetCore Mvc NewtonsoftJson which is preview version  Change to services AddControllers   AddNewtonsoftJson     Solution taken from https   stackoverflow com a 57652537 4871693

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In my case I forgot to use  JSON stringify bodyStuff

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For  net core 3 1 post url  JSON stringify yourVariable   worked like charm at the controller MyMethod  FromBody  string yourVariable

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Post the string with raw JSON  and do not forget the double quotation marks

[c#] FromBody string parameter is giving null

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