Great Expectations: Overcoming the Frustrating KeyError

Are you tired of encountering the infuriating “KeyError: Neither config : (...) nor config_defaults : {} contains a module_name key” error while working with Great Expectations? You’re not alone! This pesky issue has plagued many a data engineer and analyst, leaving them scratching their heads and searching for a solution. Fear not, dear reader, for we’re about to dive into the depths of this error and emerge victorious, armed with the knowledge and expertise to tackle it head-on.

The Background: What is Great Expectations?

Before we delve into the error, let’s take a step back and briefly discuss what Great Expectations is and why it’s an essential tool in the data engineering arsenal. Great Expectations is an open-source Python library that allows data teams to express expectations about their data, validate those expectations, and document the results. It’s an incredibly powerful tool for ensuring data quality, detecting anomalies, and automating testing.

The Error: KeyError – Neither config nor config_defaults contains a module_name key

Now, let’s get to the meat of the matter – the error itself. The “KeyError: Neither config : (...) nor config_defaults : {} contains a module_name key” error typically occurs when you’re trying to create a new Expectation Suite or validate an existing one using Great Expectations. It’s a frustrating error because it doesn’t provide much context or guidance on how to resolve it.

The Causes: Why Does This Error Occur?

There are a few common reasons why this error might occur:

• Missing or incorrect configuration files: Great Expectations relies on configuration files (usually in YAML format) to define the expectations and validation rules for your data. If these files are missing, incorrect, or not properly configured, you may encounter this error.
• Incorrect module_name or package_name: When creating an Expectation Suite, you need to specify the module_name or package_name correctly. If these values are incorrect or missing, the error may occur.
• Version conflicts or compatibility issues: Great Expectations has specific version requirements for its dependencies, and conflicts or incompatibilities can lead to this error.

Resolving the Error: Step-by-Step Instructions

Now that we’ve explored the causes, let’s get to the solutions! Follow these step-by-step instructions to resolve the “KeyError: Neither config : (...) nor config_defaults : {} contains a module_name key” error:

Step 1: Verify Configuration Files

First, ensure that your configuration files are correct and in the right location. Check that:

• The great_expectations.yml file is present in the root directory of your project.
• The ExpectationSuite configuration file (e.g., my_suite.yml) is in the correct location (usually in the expectations directory).
• The configuration files contain the necessary keys and values, including the module_name or package_name.

great_expectations.yml:
  module_name: my_module
  ...

my_suite.yml:
  module_name: my_module
  ...

Step 2: Check Module_name and Package_name

Next, verify that the module_name or package_name specified in your configuration files is correct and matches the actual module or package name.

import my_module

print(my_module.__name__)  # Should print 'my_module'

Step 3: Update Great Expectations and its Dependencies

Make sure you’re running the latest version of Great Expectations and its dependencies. You can update using pip:

pip install --upgrade great-expectations

Step 4: Reset Great Expectations Config

If the above steps don’t resolve the issue, try resetting the Great Expectations config using the following command:

great_expectations --reset-config

Troubleshooting Tips and Tricks

If you’re still encountering issues, here are some additional troubleshooting tips and tricks:

• Check for typos and spacing issues: A single typo or extra whitespace can cause the error. Double-check your configuration files and code for any mistakes.
• Use the Great Expectations CLI: The Great Expectations CLI can help you debug and validate your configuration and expectations. Try running great_expectations suite new my_suite to create a new Expectation Suite.
• Consult the Great Expectations Documentation: The official Great Expectations documentation is an exhaustive resource that covers various scenarios and edge cases. Consult it for detailed guides and tutorials.

Conclusion

The “KeyError: Neither config : (...) nor config_defaults : {} contains a module_name key” error in Great Expectations can be frustrating, but with this comprehensive guide, you should be able to resolve it and get back to ensuring the quality and integrity of your data. Remember to carefully verify your configuration files, check your module_name and package_name, and update Great Expectations and its dependencies. If all else fails, don’t hesitate to seek help from the Great Expectations community and documentation.

Common Errors	Solutions
KeyError: Neither config nor config_defaults contains a module_name key	Verify configuration files, check module_name and package_name, update Great Expectations and dependencies, and reset config

By following these steps and troubleshooting tips, you’ll be well on your way to overcoming the “KeyError: Neither config : (...) nor config_defaults : {} contains a module_name key” error and unlocking the full potential of Great Expectations for your data engineering and analysis needs.

Frequently Asked Question

Got stuck with the dreaded “KeyError: Neither config : (…) nor config_defaults : {} contains a module_name key” error in Great Expectations? Worry not, dear developer! We’ve got you covered with these 5 FAQs that’ll help you troubleshoot this pesky issue.