Jmeter does not send JSON data in POST

Question

I am trying to do a POST in jmeter with a json as the body data but I just get a 400 back. The URL I am sending to only accepts json. I have used the same curl in Postman and it worked just fine. I have tried putting the json in the parameters as a value with no name and that didnt work.

I am just trying to send {"uid":"jmtest","name":"newdevice"}.

Sorry I cant post more links.

The sampler result is

Thread Name: QA test 1-1 Sample Start: 2016-05-11 11:50:19 MDT Load time: 86 Connect Time: 51 Latency: 86 Size in bytes: 282 Headers size in bytes: 244 Body size in bytes: 38 Sample Count: 1 Error Count: 1 Data type ("text"|"bin"|""): text Response code: 400 Response message: Bad Request Response headers: HTTP/1.1 400 Bad Request Server: nginx Date: Wed, 11 May 2016 17:50:19 GMT Content-Type: application/json; charset=utf-8 Content-Length: 38 Connection: keep-alive X-Request-Id: 88339ee9-b74f-4e22-b581-e3124949d067 X-Runtime: 0.030877 HTTPSampleResult fields: ContentType: application/json; charset=utf-8 DataEncoding: utf-8 

And the request looks like

/url redacted POST data: {"devices":{"uid":"jmtest","name":"newdevice"} [no cookies] Request Headers: Connection: keep-alive Accept: application/vnd.moneydesktop.v2+json Content_Type: application/json MD-SESSION-TOKEN: redacted Content-Type: application/x-www-form-urlencoded Content-Length: 46 Host: redacted User-Agent: Apache-HttpClient/4.5.2 (Java/1.8.0_72) 

The response data is

{ :   "status":"400", :   "error":"Bad Request" } 

Answer 1

To send a POST HTTP Request with the JSON Data inside the body, need to add,

• HTTP Header Manger into your request and set the name as 'content-type' and value as 'application/json' this will attached into HTTP request header and what ever the data inside your request body will send as json format.

Image 1:Set HTTP Header Manager,

Image 2:Set HTTP Request Body Data

Answer 2

1. Make sure your HTTP Header Manager is configured to send Content-Type header with the value of application/json
2. Given you have samplers like "home page" and "login" it might be the case you're missing HTTP Cookie Manager
3. The most straightforward way to see what's wrong is to capture requests sent by Postman (whatever it is) and JMeter by a sniffer tool like Wireshark, identify the differences and configure JMeter accordingly.
4. Finally, it looks like you're using some developer snapshot so approach to pass JSON payload as 1st argument without name might not work. Try switching to "Body Data" instead.
5. If above steps won't help update your question with screenshots of View Results Tree listener (all 3 tabs) and Postman

Check out Testing SOAP/REST Web Services Using JMeter for more tips.