PyMongonnator

Just a simple production-ready mongo paginator written in Python for PyMongo package using bucket pattern. This package is based in this wonderful Javascript module: mongo-cursor-pagination. The reason for making this library was to paginate over thousands of data stored in mongo collections and we didn't find any library that seamlessly integrated with Pymongo.

Installation

pip install PyMongonnator

Python version compat

PyMongonnator is compatible with the latest Python3 versions: 3, 3.5, 3.6, 3.7, 3.8.

Usage

PyMongonnator exposes two ways to paginate over collections:

• Built-in API importing overriden MongoClient class.
• Explicit API passing a MongoClient collection into Paginator method.

Options

• query: a SON object specifying elements which must be present for a document to be included in the result set. Default is {} (query all).
• limit: Number of documents per page. Default is 75.
• ordering_case: Ordering sense when retrieving documents from mongo. Valid options are:
  • ASCENDING: Ascending sort order.
  • DESCENDING: Descending sort order (default).
• ordering_field: Field to order collections. Default is _id.
• projection: a dict specifying the fields to include or exclude. Please note that the id cannot be excluded because is mandatory in pagination. Default is {} (include only the _id).
• prev_page: Previous pagination pointer. When no previous page is available, will be None. Default is None.
• next_page: Next pagination pointer. When no next page is available, will be None. Default is None.
• automatic_pagination: If you want to paginate automatically in batches of limit over entire collection. Default is True.

When options are set, they should remain unchanged during the whole pagination process except pagination pointers (prev_page/next_page).

Built-in API (recommended)

from mongonator import MongoClientWithPagination, ASCENDING


MONGO_URI = 'mongodb://[user]:[password]@[host]:[port]/admin'
DATABASE = 'database'
COLLECTION = 'collection'

# Instantiate mongo client with pagination
mongo_client = MongoClientWithPagination(MONGO_URI)
db = mongo_client[DATABASE]
col = db[COLLECTION]

query_filter = {'name': {'$ne': None}}


# Paginate automatically in batches of 5
for d in col.paginate(query=query_filter, limit=5, projection={'email': 1, 'name': 1},
                      ordering_field='name', ordering=ASCENDING):
    print(d.response)
    print(d.batch_size)


# Paginate manually in batches of 5
page = col.paginate(query=query_filter, limit=5, projection={'email': 1, 'name': 1},
                      ordering_field='name', ordering=ASCENDING, automatic_pagination=False)


# ahead (next five documents)
next_batch_of_five = col.paginate(query=query_filter, limit=5, projection={'email': 1, 'name': 1},
                      ordering_field='name', ordering=ASCENDING, automatic_pagination=False, next_page=page.next_page)

               
# back (prev five documents from next_batch_of_five situation)
prev_batch_of_five = col.paginate(query=query_filter, limit=5, projection={'email': 1, 'name': 1},
                      ordering_field='name', ordering=ASCENDING, automatic_pagination=False, next_page=next_batch_of_five.prev_page)

This method is intended when you just started a new project from scratch or for existing projects if you are willing to substitute every MongoClient instance for MongoClientWithPagination.

Explicit API

from mongonator import Paginate, ASCENDING
from pymongo import MongoClient


MONGO_URI = 'mongodb://[user]:[password]@[host]:[port]/admin'
DATABASE = 'database'
COLLECTION = 'collection'

query_filter = {'name': {'$ne': None}}

# Instantiate MongoClient from pymongo
with MongoClient(MONGO_URI) as mongo_client:
    db = mongo_client[DATABASE]
    col = db[COLLECTION]

    # Manual pagination in batches of 2
    paginator = Paginate(
        collection=col,
        query=query_filter,
        limit=2,
        ordering_field='email',
        ordering_case=ASCENDING,
        projection={'email': 1, 'name': 1},
        automatic_pagination=False
    ).paginate()

    # Print results
    print("Response: ", paginator.response)
    print("Prev page: ", paginator.prev_page)
    print("Next page: ", paginator.next_page)
    print("Batch size: ", paginator.batch_size)

    # Manual pagination for two next results...
    paginator = Paginate(
        collection=col,
        query=query_filter,
        limit=2,
        ordering_field='email',
        ordering_case=ASCENDING,
        projection={'email': 1, 'name': 1},
        automatic_pagination=False,
        next_page=paginator.next_page,
    ).paginate()

    # Print results
    print("Response: ", paginator.response)
    print("Prev page: ", paginator.prev_page)
    print("Next page: ", paginator.next_page)
    print("Batch size: ", paginator.batch_size)
    
    # ... Or simply use automatic pagination in batches of 2 (starting in first document)
    for d in Paginate(
        collection=col,
        query=query_filter,
        limit=2,
        ordering_field='email',
        ordering_case=ASCENDING,
        projection={'email': 1, 'name': 1},
        automatic_pagination=True,
    ).paginate():
        print(d.response)

This method is intended when you have a big project in production and is not possible to substitute every MongoClient call.