API to Perform a build: How to put parameters inside request body?

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1

Jenkins setup:
Jenkins version is Jenkins 2.426.3

I know there is api /job/{jobName}/buildWithParameters?longParam=longValue . Usually this works. However, for some reason, if the longValue is very long, it will give a 414 error.
Then I am trying to move the very long parameter from http parameters to request body.
Learned from internet that it can be done by putting into a json list, wrapped with parameter, e.g.:

{
  "parameter": [
    {
      "name": "longParam",
      "value": "this_is_a_very_very_long_paramter!"
    }
  ]
}

Though it gives an 201, the build does not recognize this parameter and uses the default value.

Am I using it in a somewhat wrong way? Or the it must be put in http parameters?

2

When you pass data as json you need to do it this way (this basically mimics posting via the UI):
Here I have a pipeline job that has a parameter named test.

curl --user <user>:<token> -X POST http://localhost:9090/job/testpipeline/build --data-urlencode json='{"parameter": [{"name": "test", "value": "TEST"}]}'

You don’t need to pass all parameters, parameters that are not defined will get the default.