Book Image

Learn MongoDB 4.x

By : Doug Bierer
Book Image

Learn MongoDB 4.x

By: Doug Bierer

Overview of this book

When it comes to managing a high volume of unstructured and non-relational datasets, MongoDB is the defacto database management system (DBMS) for DBAs and data architects. This updated book includes the latest release and covers every feature in MongoDB 4.x, while helping you get hands-on with building a MongoDB database app. You’ll get to grips with MongoDB 4.x concepts such as indexes, database design, data modeling, authentication, and aggregation. As you progress, you’ll cover tasks such as performing routine operations when developing a dynamic database-driven website. Using examples, you’ll learn how to work with queries and regular database operations. The book will not only guide you through design and implementation, but also help you monitor operations to achieve optimal performance and secure your MongoDB database systems. You’ll also be introduced to advanced techniques such as aggregation, map-reduce, complex queries, and generating ad hoc financial reports on the fly. Later, the book shows you how to work with multiple collections as well as embedded arrays and documents, before finally exploring key topics such as replication, sharding, and security using practical examples. By the end of this book, you’ll be well-versed with MongoDB 4.x and be able to perform development and administrative tasks associated with this NoSQL database.
Table of Contents (22 chapters)
1
Section 1: Essentials
5
Section 2: Building a Database-Driven Web Application
9
Section 3: Digging Deeper
13
Section 4: Replication, Sharding, and Security in a Financial Environment
14
Working with Complex Documents Across Collections

Adding pagination to the responder class

The next step is to add a method to the web.responder.html.Html class that accepts the output produced by fetchPaginatedByCustKey() and returns HTML. We also need to accept the current page number and a base URL to create links to the previous and next pages. Note that if the previous page number drops below 0, we simply reset it to 0.

The method might appear as follows:

    # web.responder.html.Html
def buildPurchaseHistory(self, purchHist, pageNum, baseUrl) :
import locale
nextPage = pageNum + 1
prevPage = pageNum - 1
if prevPage < 0 : prevPage = 0
We do not define an upper limit for the pagination in this illustration, so the link for the next page might go past the end of the query result. In our example, in this case, a page with no results is displayed. If an upper limit is needed, create a domain service method that returns the value of pymongo.collection.count_documents(). You could then multiply the...