Solving the TypeError When Matching Values in a Nested Dictionary with Python

Learn how to effectively match values from nested dictionaries in Python using the TestRail API. This guide covers common mistakes and provides solutions for avoiding `TypeError` exceptions.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Problems matching values from nested dictionary

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Solving the TypeError When Matching Values in a Nested Dictionary with Python

Handling complex data structures is a common challenge in programming, especially when working with APIs that return nested dictionaries. If you're using the TestRail API and experiencing issues while trying to retrieve specific test run IDs based on their names, you may unfortunately run into a TypeError. In this post, we'll dive into this problem and walk through how to resolve it effectively.

The Problem

When you implement the following scenario in your code, you want to scan through all test runs, locate a specific test run by its name, and return the corresponding ID. Here's the problematic code snippet:

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

However, when executing the code as is, you encounter an error:

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

This error arises because you're trying to access dictionary keys in the wrong context. Let's explore the underlying issues and how to fix them.

Understanding the Data Structure

The data structure returned from the TestRail API contains nested dictionaries. Here’s a simplified representation of the output you're dealing with:

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

In this structure, the runs key contains a list of dictionaries. Each dictionary represents a test run, complete with various properties like id and name.

The Solution

To fix the error, adjust the loop to iterate over the nested runs list within the main dictionary. Here's how you should structure your code:

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

What Changed?

Accessing the Right Layer: Instead of iterating directly over test_runs, which is a dictionary, you now access test_runs['runs']. This correctly targets the list of test run dictionaries.

Important Note on Error Handling

While the above modification will prevent the TypeError, it's also important to consider what happens if the specified test run name is not found. If run_id is never assigned, the following return will raise an exception. Here are a couple of ways to handle this potential issue:

Default Value:
Set a default value for run_id at the start of your method:

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

This way, if no match is found, None (or another sentinel value) is returned.

Raising an Exception:
You can raise a custom exception to provide clearer feedback:

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

Conclusion

By correctly iterating over the runs in the response from the TestRail API, you have resolved the TypeError and improved the robustness of your code. Such practices help ensure smoother interactions with data structures in Python, especially when navigating nested dictionaries. Happy coding!