reference:JMeter basics: the difference between request parameters and body data
JMeter basics: the difference between request parameters Parameters and Body Data

Jmeter contains two parameterization methods: Parameters and Body Data. What is the difference?

• When using Parameters, the Content-Type is not passed, or application/x-www-form-urlencoded is passed directly, if there is an error in passing application/json.
• When using Body Data, Content-Type can be passed application/x-www-form-urlencoded or application/json. The difference between the two is the data format.

Generally speaking, Parameters are used for Get requests and Body Data is used for Post requests.

The exact statement for Post is:

• For normal post request and upload interface, select Parameters.
• json and xml point data format request interface, select Body.

To explain in detail, according to the format of the post request data, there are two cases: map format and json format.

• Post request data is in map format

When the post request data is in map format, that is, the parameter name and the parameter value are key-value key-value pairs, the requested parameters can be added in the Parameters parameter table

When using jmeter, add the request data in json format to the http request BodyData

In addition, due to the POST request method, if the content-type of Headers is not set, the data will be submitted in application/x-www-form-urlencoded by default. In order to ensure that the Post request is in json format, you also need to declare in the request header that the format of the request parameters is json. The specific operations are as follows:

Thread Group right click Add "Config Element" HTTP Header Manager, open the HTTP header manager, Add a Name as Content-Type, Value as application/json
As shown in the figure below, when logging in, the parameter name and parameter value are key-value pairs, and the requested parameters can be added to the Parameters parameter table.