Let us first look at the below three features:

php://input: This is a read-only stream that allows us to read raw data from the request body. It returns all the raw data after the HTTP-headers of the request, regardless of the content type.
file_get_contents() function: This function in PHP is used to read a file into a string.
json_decode() function: This function takes a JSON string and converts it into a PHP variable that may be an array or an object.
It is known that the all of the post data can be received in a PHP script using the $_POST[] global variable. But this fails in the case when we want to receive JSON string as post data. To receive JSON string we can use the “php://input” along with the function file_get_contents() which helps us receive JSON data as a file and reads it into a string.

Later, we can use the json_decode() function to decode the JSON string.

// Takes raw data from the request
$json = file_get_contents('php://input');

// Converts it into a PHP object
$data = json_decode($json);