How to Paginate a List with a Generator in Python

Define a generator that yields list items in fixed-size pages, simulating pagination for cloud resource APIs.

Easy Python 3.9+ Aug 9, 2026 Cloud + Python 11 views 0 copies

generator pagination cloud mock list

Python code

14 lines

Python 3.9+

from typing import List, Iterator

def paginate_generator(items: List[str], page_size: int = 3) -> Iterator[List[str]]:
    """Yield items in fixed-size chunks with a mock pagination pattern."""
    for i in range(0, len(items), page_size):
        yield items[i:i + page_size]

if __name__ == "__main__":
    resources = ["user_001", "user_002", "user_003",
                 "post_101", "post_102", "post_103"]
    
    print("All resources:")
    for page_num, page in enumerate(paginate_generator(resources), start=1):
        print(f"  Page {page_num}: {page}")

Output

stdout

All resources:
  Page 1: ['user_001', 'user_002', 'user_003']
  Page 2: ['post_101', 'post_102', 'post_103']

How it works

The generator uses range(0, len(items), page_size) to step through the list in chunks. Each yield returns a slice items[i:i+page_size], producing one page at a time. Because it's a generator, the pages are produced lazily — memory stays low even for large resource lists. When iterating with enumerate, Python automatically retrieves each page and assigns a page number. This pattern is ideal for mocking cloud pagination (e.g., AWS or GCP resource listings).

Common mistakes

Using `return` inside the generator loop, which stops iteration after the first page.
Forgetting to use `page_size` in both the range step and the slice end, causing overlapping or missing items.
Assuming the final page is always full when the total length isn't divisible by the page size.

Variations

Use `itertools.islice` with a while loop to paginate an infinite or iterator source.
Add a `fetch_page(page_num)` function that mimics real API calls with offset-based pagination.

Real-world use cases

Mocking AWS S3 list_objects_v2 pagination in unit tests to avoid real network calls.
Building a CLI script that batches cloud instance IDs for resource tagging or deletion.
Simulating API pagination in a development environment when the backend isn't ready.

How to Paginate a List with a Generator in Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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