Write dictionaries to CSV.
Write a list of dictionaries to a CSV file with a header row and a predictable column order.
import csv
rows = [{"name": "Ada", "score": 98}, {"name": "Grace", "score": 95}]
with open("scores.csv", "w", newline="", encoding="utf-8") as file:
writer = csv.DictWriter(file, fieldnames=["name", "score"])
writer.writeheader()
writer.writerows(rows)
print("Saved 2 rows")Expected output EXAMPLE
Saved 2 rows
Details
Uses only the Python standard library; no pip packages are required. See the verification record below for the exact Python version tested.
Replaces scores.csv if it exists. Do not open CSV from untrusted sources in a spreadsheet without checking for formula injection.
Tested on Ubuntu 24.04.5 LTS · · Python 3.12.3 · python3 3.12.3-0ubuntu2.1
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged) / C.UTF-8
- Interpreter invocation
python3 -c <published code>- Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd- Code SHA-256
81d7481e5ca13b72fc0f33554bf22fb2019c3de1ad93c189059bfb195c91d6a2- Dependencies
- python3 3.12.3-0ubuntu2.1
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
# No input files required.
Observed standard output
Saved 2 rows
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.
Additional assertions that passed
Checks recorded by the test harness. Where Python assertions are shown, browser cases use Playwright and simulator cases may inspect pin transitions: result.stdout is captured output, work is the temporary directory, and Path is pathlib.Path. The harness also imports json and csv.
assert list(csv.DictReader(Path('scores.csv').open())) == [{'name':'Ada','score':'98'}, {'name':'Grace','score':'95'}]