Hello everyone
When writing code before
Value; you want to modify JRequest::getVar()
Discovery
Under some situations
Directly modify $_POST parameter is invalid
Then I tried so many ways
For example:

JRequest::setVar('jform','1');
JRequest::setVar('jform',array(),'POST',TRUE);

 

no use(but no error)(。A。)

After reading this article
https://groups.google.com/forum/#!topic/joomla-dev-general/hF9ynwH8ezY

Finding the right way it should be

JFactory::getApplication()->input->post->set('varname', $varvalue);
or
JFactory::getApplication()->input->get->set('varname', $varvalue);

 

For your reference
Thanksgiving(゚∀゚)