Generate Email: Build an Email Template Engine with Variable Substitution and Conditionals

Question

## Problem

Implement a simple email template engine. A template is a string that may contain:
- Variable substitutions: `{{name}}`, `{{order_id}}`
- Conditional blocks: `{% if premium %}...{% endif %}`

Given a template string and a context dict, render the final email string. Unknown variables render as empty string. Conditions are truthy/falsy based on the context value.

```python
def render_email(template: str, context: dict) -> str:
    pass
```

**Example:**
```
template = """Hi {{name}},
Your order {{order_id}} is confirmed.
{% if premium %}You get free shipping!{% endif %}
Thanks!"""

context = {"name": "Alice", "order_id": "ORD-99", "premium": True}

Output:
"Hi Alice,
Your order ORD-99 is confirmed.
You get free shipping!
Thanks!"

With premium=False: the conditional block is omitted.
```

## Follow-ups

1. How would you handle nested conditionals `{% if a %}{% if b %}...{% endif %}{% endif %}`?
2. How would you add a `{% for item in items %}...{% endfor %}` loop construct?
3. What security issues arise if template strings come from user input? (SSTI)
4. How would you unit test this engine exhaustively, including edge cases like missing `{% endif %}`?

Generate Email: Build an Email Template Engine with Variable Substitution and Conditionals

Question Details

Full Details

Topics

More from Roblox