Laravel 5.2 - Use a String as a Custom Primary Key for Eloquent Table becomes 0

Stefan Izdrail

Founder & Senior Architect · 2026-06-29

Laravel Company
Title: Understanding Custom Primary Key Usage in Laravel Eloquent Models with String Values Body:

When working with databases, especially using modern frameworks like Laravel, it is essential to understand how to customize the primary keys and the associated tables. In this blog post, we will discuss a unique problem related to using a string as a custom primary key in Laravel 5.2 (Eloquent table becomes 0) and its possible solutions.

Problem Explanation

As stated in the example, you are trying to use an email address as the table's primary key, which is a string value. When retrieving data with this primary key (verification_token), you observe that the primary key's value becomes '0'. This behavior occurs when MySQL performs type coercion on non-numeric keys to ensure consistency across the database. In this case, since the verification_token column stores a string value (an email address), MySQL automatically converts it to an integer data type.

Example Database

Possible Solutions

  1. Use a different primary key: Instead of using the email address as your primary key, consider changing it to an integer or other numeric data type that can support unique identification. You could use UUIDs (Universally Unique Identifier) if you need a globally unique identifier.
  2. Enforce string primary keys in your database schema: If you require a particular data type, such as a string primary key for your email address column, you can create a unique constraint on the column to ensure its uniqueness. In this case, it will prevent MySQL from coercing the value to an integer.
  3. Use the casts property in Eloquent models: You can define how specific data types are treated by your model with the casts property in your UserVerification Model class. For example, you can set the primaryKey attribute to 'email' and then use a custom cast function to ensure your email address is not converted to an integer.
  4. Use a different database engine: If the problem continues to persist even after implementing the above solutions, it might be caused by a specific limitation of the MyISAM storage engine. In this case, you could consider switching to another database engine that better supports string primary keys, such as InnoDB or MariaDB.

Conclusion

Though Laravel provides built-in functionality for handling various data types, it is crucial to understand the underlying database principles and limitations. By following the best practices mentioned above, you can efficiently use custom primary keys with string values in your Laravel applications.