Home Implementing Polyglot Persistence – Part 2

Implementing Polyglot Persistence – Part 2

In part 1 of this series, I created a product catalog repository interface and a simple in-memory repository. In this post I am going to start the implementation of a repository going against a MongoDB database.

There are a couple of options to get a MongoDB database setup.

  1. You could stand up your own VM(s) using this image from VM Depot provided by Cognosys. It will provide a MongoDB instance running on ubuntu.
  2. Use Mongolab, which essentially is MongoDB-as-a-Service.

For this implementation, I’m going with the latter.

In this post, I’ll share my experience creating the database and populating it with some data.

Create a MongoDB Database

If you don’t already have a Mongolab account, you can get one here.

To create a database, click the link to create a new database and fill out the page. For example:

MongoLab Cloud Providers

After a few seconds, I was presented with this page, providing a link to my new database “rickraincommerce“.

Mongo Databases

Populate the Database

Now that I have a database I can work with, I need to add some data. Clicking on my database takes me to a page that displays my database connection string. It also has tabs to manage collections (think of tables if you come from a RDBMS world), users, backups, statistics, and tools. A pretty handy page.

You can use this web interface to create a collection and add documents to it. You could write a simple little client to add documents. Use the MongoDB shell. There are many ways to skin this cat. As I was playing around with this, I came up with an approach using the Mongolab REST API’s. That’s right! They provide REST API’s too!!!

Being a big fan of REST API’s, I chose to try out this approach to populate my database with a “products” collection.

Get a Mongolab REST API Key

All the Mongolab REST API’s require an API key. You can get yours by clicking on your “user” link in the upper-right corner of your Mongolab screen.

Mongolab API Keys

This will take you to a screen that will show you your API key. There’s also a button to regenerate your key ( a good practice is to roll your keys regularly ). This screen also provides the base URL for the API’s.

Mongolab API Key

Get Some Product Data to Add to the Database

I already have some test data in this repository I created in Part 1 of this series. So, I just decided to run this solution and open up Fiddler to get the data. All my test products have a product Id between 101 and 108, so this search query against my in-memory repository will give me all my data at once.

NOTE: If you want to skip to the next section, a copy of my test data in JSON format is available here.

Fiddler - Search Prodducts

Copy just the JSON content from the response ( don’t copy the headers ) and save this off somewhere ( notepad for example ). A small (optional) change I made to the data is I deleted the “Id” field from each product. It’s perfectly fine to leave it, but Mongolab is going to create a new “_id” for each product anyway when I add it so I’m going to use that for the Id going forward.

Fiddler - Search Products Result

Add Product Data to MongoDB Using Mongolab REST API

Using the Mongolab REST API URL, https://api.mongolab.com/api/1/databases?apiKey=<your-api-key>, a quick POST from Fiddler will take care of this.

Fiddler - POST Add Product

Going back to the Mongolab collections, I see my products collection was created and has 8 documents (my 8 test products) in it. Clicking on the products will drill into the document for each product.

Monglab collections

Looking at just the first few products I can verify the data was POSTed correctly. I also see the “_id” field that MongoDB created for each of these products. I’ll talk more about this field in Part-3.

Monglab - Products collection

Is it Really Running in Azure?

Pulling the server name from the connection string, I ran nslookup on it just to see how it resolves. Sure enough, it’s got a *.cloudapp.net URL, where all cloud services in Azure exist.


That’s it! Now I’ve got a MongoDB instance with some data in it. In Part-3 of this series I’ll start writing the code to interact with it.

This post is licensed under CC BY 4.0 by the author.

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