What is the `json` module best practices?

Question

Accepted Answer

**json** — JSON encoding/decoding with safety considerations.

```python
import json

# Serialization
data = {"users": [{"name": "Alice", "age": 30}]}
json_str = json.dumps(data, indent=2, ensure_ascii=False)

# Deserialization
parsed = json.loads(json_str)

# File I/O
with open("data.json", "w") as f:
    json.dump(data, f, indent=2)

with open("data.json") as f:
    data = json.load(f)

# Custom encoder
class DateTimeEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, datetime):
            return obj.isoformat()
        return super().default(obj)

json.dumps({"date": datetime.now()}, cls=DateTimeEncoder)

# Safe parsing (security)
def safe_parse(json_str):
    try:
        return json.loads(json_str)
    except json.JSONDecodeError as e:
        logger.error("Invalid JSON: %s", e)
        return None
```

**Best practices:**
- Always handle JSONDecodeError.
- Use json.loads() not eval().
- Use ensure_ascii=False for Unicode.

Python: What is the `json` module best practices?