'str' object has no attribute 'h264' - performance

Question

trying to do rasp. pi project "parent detector". fixed error with camera. now having an error i have 0 idea how to fix.
already had camera error fixed. old raspberry pi model. don't know what model. looked at project site and at answers and there shouldn't be an error.
entire error says:
filename= "{0:%Y}-{0:%m}-{0:%d}.h264
Attribute Error: 'str' object has no attribute 'h264'
this is the code for the project.
from gipiozero import MotionSensor
import picamera
from datetime import datetime
pir=MotionSensor(4)
while True:
filename= "{0:%Y}-{0:%m}-{0:%d}.h264
pir.wait_for_motion()
camera.start_recording(filename)
pir.wait_no_motion()
camera.stop_recording()
expected a motion detecting camera. got errors. gave up, teacher is forcing me to do this.

Answer 1

Regarding the line:
filename= "{0:%Y}-{0:%m}-{0:%d}.h264
you almost certainly should have a closing " at the end. However, given the error, I'm pretty certain what you actually have is something like:
filename= "{0:%Y}-{0:%m}-{0:%d}".h264
which would cause you to try and access the h264 property of that string:
>>> "{0:%Y}-{0:%m}-{0:%d}".h264
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'str' object has no attribute 'h264'
In addition, you are probably trying to construct a filename from a datetime object, and this can be done with:
>>> from datetime import datetime as dt
>>> "{0:%Y}-{0:%m}-{0:%d}.h264".format(dt.now())
'2019-06-11.h264'