JMeter - JSON parse error: Unexpected character

Question

I am trying to add dynamic Post response on one rest API URL(http:IP:9000/page) with data as a JSON request in file format, So to add that file in post body I use the command:

{__$FileToString(C:\Users\user\Desktop\Test\${__eval(${Json_request.txt})},,)}

and the JSON file data is:

{

"User ID": 204120,

"name": "New User",


"Description": [{"john",204110,"robotics"},

                 {"smith",204111,"AI"},

                 {"Jack",204112,"Machinelearning"}]
"Status": "Post request Successfully"

}

But after running this script there is an error in the response body in view results tree:

{"timestamp":1574329356300,"status":400,"error":"Bad 
Request","exception":"org.springframework.http.converter.HttpMessageNotReadableException",
"message":"JSON parse error: Unexpected character ('_' (code 95)): was expecting double-quote to start field name; nested exception is 
com.fasterxml.jackson.core.JsonParseException: Unexpected character 
('_' (code 95)): was expecting double-quote to start field name\n at 
[Source: java.io.PushbackInputStream@73210d3e; line: 1, column: 3]","path":"/page"}

Answer 1

1. Your data is not a valid JSON, you can check it yourself using i.e. online JSON formatter and validator

   

2. You syntax of combination of __eval() and __FileToString() functions is incorrect, you should wrap the __FileToString() function into the __eval() and you're doing the opposite thing:

   ${__eval(${__FileToString(${Json_request.txt},,)})}
   

   More information: Here’s What to Do to Combine Multiple JMeter Variables

Answer 2

Your JSON is not valid:

1 {
2   "User ID": 204120,
3   "name": "New User",
4   "Description": [{
5       "name": "john",
6       "id": 204110,
7       "type": "robotics"
8   }],
9   "Status": "Post request Successfully"
10 }

You need to add a name to the value on lines 5,6,7

Or you need to remove the {} brackets to make it valid

"Description": [ "john", 204110, "robotics" ]

Also you missed a comma on line 8, at the end of the Description block.

Maybe you should study the JSON format: http://www.json.org/ and use a JSON validator first https://jsonlint.com/