How to Remove Empty Dictionary Values When Dumping YAML in Python

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Introduction

The Problem

Let's imagine you're developing a script that collects data from your Configuration Management Database (CMDB) to create an Ansible inventory. During this process, you've come across the situation where your generated YAML includes empty dictionary brackets {} for each host. Here's an example of what you might be seeing in your output:

[[See Video to Reveal this Text or Code Snippet]]

The desired output, however, should not display those empty dictionaries:

[[See Video to Reveal this Text or Code Snippet]]

In this post, we'll walk you through a solution using Jinja to format the hosts dynamically, resulting in a cleaner YAML output.

Solution Overview

To eliminate the empty dictionary values in your YAML output, we can utilize Jinja templating to process the hosts and control their formatting based on whether they contain data.

Steps to Implement the Solution

Define the Hosts Dictionary: Start with the existing nested dictionary for your hosts, including empty entries.

Use a Jinja Template: We will create a Jinja template to iterate through the dictionary and conditionally format each host based on whether it has associated data.

Compile and Dump the YAML: Finally, we will compile our Jinja template output back into the desired YAML format.

Step 1: Define the Hosts Dictionary

First, define your initial hosts dictionary. For example:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Use a Jinja Template to Format the Hosts

Next, create a Jinja template string that iterates through the hosts and outputs them according to whether they contain data:

[[See Video to Reveal this Text or Code Snippet]]

This template ensures that hosts without any attributes will be outputted without an empty dictionary.

Step 3: Create the Output Dictionary

Now, construct a new output dictionary using the processed hosts:

[[See Video to Reveal this Text or Code Snippet]]

Final Example Playbook

Here's a complete Ansible playbook to demonstrate the solution:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

In this post, we explored how to remove empty dictionary values when dumping YAML in Python. By leveraging Jinja for templating, we can process our inventory data effectively, ensuring our output remains clear and readable. You can easily adapt this method to suit your specific needs in your Python scripts or Ansible playbooks.

By following these instructions, you'll ensure that your YAML outputs are not only functional but also clean and well-structured, enhancing both readability and usability.