Debug Your Infrastructure

Get Instant Solutions for Kubernetes, Databases, Docker and more

AWS CloudWatch
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.
Pod Stuck in CrashLoopBackOff
Database connection timeout
Docker Container won't Start
Kubernetes ingress not working
Redis connection refused
CI/CD pipeline failing

Pydantic A field expected to match a regex pattern did not match.

The value provided for a field does not conform to the specified regex pattern in the Pydantic model.

Understanding Pydantic

Pydantic is a data validation and settings management library for Python, based on Python type annotations. It is designed to provide a simple and efficient way to validate and parse data, ensuring that the data conforms to the expected types and formats. Pydantic is widely used in applications where data integrity is crucial, such as in web APIs, data processing pipelines, and configuration management.

Recognizing the Symptom

When using Pydantic, you might encounter the error code value_error.regex. This error indicates that a field in your Pydantic model was expected to match a specific regular expression pattern, but the provided value did not match the pattern. This can lead to data validation failures and potentially cause your application to behave unexpectedly.

Example of the Error

Consider a Pydantic model where an email field is expected to match a standard email regex pattern. If the input value does not conform to this pattern, Pydantic will raise a value_error.regex error.

Details About the Issue

The value_error.regex error occurs when a field in a Pydantic model is defined with a regex pattern constraint, and the input value fails to match this pattern. This is a common issue when dealing with fields that require specific formats, such as email addresses, phone numbers, or custom identifiers.

Understanding Regular Expressions

Regular expressions (regex) are sequences of characters that define a search pattern. They are commonly used for string matching and validation. In Pydantic, you can use regex patterns to enforce specific formats for your data fields. For more information on regular expressions, you can refer to the Python regex documentation.

Steps to Fix the Issue

To resolve the value_error.regex error, follow these steps:

1. Review the Regex Pattern

Ensure that the regex pattern defined in your Pydantic model accurately represents the format you expect. You can test your regex pattern using online tools such as Regex101 to verify its correctness.

2. Validate the Input Data

Check the input data being passed to the Pydantic model. Ensure that it conforms to the expected format defined by the regex pattern. If necessary, preprocess or sanitize the input data before validation.

3. Update the Pydantic Model

If the regex pattern or the expected format needs to be adjusted, update the Pydantic model accordingly. For example, if you are validating an email field, ensure that the regex pattern correctly matches valid email addresses.

from pydantic import BaseModel, constr

class UserModel(BaseModel):
email: constr(regex=r'^[\w\.-]+@[\w\.-]+\.\w+$')

4. Test the Changes

After making changes, test your application to ensure that the value_error.regex error is resolved and that the data validation works as expected.

Conclusion

By understanding and addressing the value_error.regex error in Pydantic, you can ensure that your data validation logic is robust and reliable. Regular expressions are powerful tools for enforcing data formats, and with careful implementation, you can prevent common data integrity issues in your applications.

Master 

Pydantic A field expected to match a regex pattern did not match.

 debugging in Minutes

— Grab the Ultimate Cheatsheet

(Perfect for DevOps & SREs)

Most-used commands
Real-world configs/examples
Handy troubleshooting shortcuts
Your email is safe with us. No spam, ever.

Thankyou for your submission

We have sent the cheatsheet on your email!
Oops! Something went wrong while submitting the form.

Pydantic A field expected to match a regex pattern did not match.

Cheatsheet

(Perfect for DevOps & SREs)

Most-used commands
Your email is safe thing.

Thankyou for your submission

We have sent the cheatsheet on your email!
Oops! Something went wrong while submitting the form.

MORE ISSUES

Deep Sea Tech Inc. — Made with ❤️ in Bangalore & San Francisco 🏢

Doctor Droid