Hệ thống tệp trong Python

paths.py

from pathlib import Path

thu_muc = Path("data"); thu_muc.mkdir(exist_ok=True)
tep = thu_muc / "ghi_chu.txt"
tep.write_text("Xin chao", encoding="utf-8")

print(tep.exists(), tep.suffix, tep.stem, tep.stat().st_size)
print([p.name for p in thu_muc.glob("*.txt")])     # tim 1 cap
# thu_muc.rglob("*.py")  -> tim DE QUY moi cap con

True .txt ghi_chu 8
['ghi_chu.txt']

rw.py

with open("nhat_ky.txt", "w", encoding="utf-8") as f:
    f.write("dong 1\n"); f.write("dong 2\n")

with open("nhat_ky.txt", encoding="utf-8") as f:
    for dong in f:               # doc tung dong (luoi, it bo nho)
        print(dong.rstrip())

dong 1
dong 2

ctx.py

# Cach 1: class voi __enter__/__exit__
class Mo:
    def __enter__(self):
        print("mo tai nguyen"); return "r"
    def __exit__(self, exc_type, exc, tb):
        print("don dep")          # chay du co loi hay khong

# Cach 2 (gon hon): @contextmanager tren mot generator
from contextlib import contextmanager

@contextmanager
def mo():
    print("setup")               # truoc yield = __enter__
    try:
        yield 42                 # gia tri gan cho "as"
    finally:
        print("teardown")        # sau yield = __exit__ (luon chay)

with mo() as x:
    print("dung", x)

setup
dung 42
teardown

json_io.py

import json
nguoi = {"ten": "An", "diem": [8, 9, 10], "dat": True}

with open("nguoi.json", "w", encoding="utf-8") as f:
    json.dump(nguoi, f, ensure_ascii=False, indent=2)   # giu tieng Viet

with open("nguoi.json", encoding="utf-8") as f:
    lai = json.load(f)
print(lai["ten"], lai == nguoi)

An True

csv_io.py

import csv
rows = [{"ten": "An", "diem": 8}, {"ten": "Binh", "diem": 9}]

with open("diem.csv", "w", newline="", encoding="utf-8") as f:
    w = csv.DictWriter(f, fieldnames=["ten", "diem"])
    w.writeheader(); w.writerows(rows)

with open("diem.csv", newline="", encoding="utf-8") as f:
    doc = list(csv.DictReader(f))
print(doc[0]["ten"], len(doc))

An 2

atomic.py

import os
from pathlib import Path

def ghi_an_toan(path: str, text: str):
    p = Path(path)
    tmp = p.with_suffix(p.suffix + ".tmp")
    tmp.write_text(text, encoding="utf-8")   # ghi ra file TAM truoc
    os.replace(tmp, p)                        # doi ten NGUYEN TU -> an toan

ghi_an_toan("config.json", '{"ok": true}')