fail to publish to a different message type

edit

Hi everyone :) I wrote a node called translater that subscribes to a the topic pose_before and publishes to another topic pose_after. The topic pose_before is of message type "PoseWithCovarianceStamped" and pose_after is "TransformStamped". The issue is that all values in pose_after remain 0 when they're being published.

#!/usr/bin/env python
import rospy
from geometry_msgs.msg import PoseWithCovarianceStamped
from geometry_msgs.msg import TransformStamped

def callback(data):
    TransformStamped().transform.translation.x = data.pose.pose.position.x
    TransformStamped().transform.translation.y = data.pose.pose.position.y
    TransformStamped().transform.translation.z = data.pose.pose.position.z
    TransformStamped().transform.rotation.x = data.pose.pose.orientation.x
    TransformStamped().transform.rotation.y = data.pose.pose.orientation.y
    TransformStamped().transform.rotation.z = data.pose.pose.orientation.z
    TransformStamped().transform.rotation.w = data.pose.pose.orientation.w
def listener():
    pub = rospy.Publisher('pose_after', TransformStamped, queue_size=40)
    pose_after = TransformStamped()
    rospy.init_node('translater', anonymous=True)
    rospy.loginfo("Publishing pose_after")
    rospy.Subscriber('pose_before', PoseWithCovarianceStamped, callback)
    rate = rospy.Rate(40)
    pose_after.header.stamp = rospy.Time.now()
    pose_after.child_frame_id = 'base_footprint'
    print(pose_after.transform.translation.x) # this prints (0,0)
    while not rospy.is_shutdown():
        pub.publish(pose_after)
        rate.sleep()

if __name__ == '__main__':
    try:
        listener()
    except rospy.ROSInterruptException:
        pass
 

When I put the print line in callback then it actually is able to print the correct values, so I'm wondering why the values are lost outside of the callback. I've also tried assigning a global variable inside the callback but still didn't work.