Eloquent casts decimal as string
Stefan Izdrail
Founder & Senior Architect · 2026-06-29
Title: Understanding Eloquent's Decimal Casting Issues and How to Fix Them
Body:
Introduction
When working with Eloquent models, you may encounter situations where decimal fields representing monetary values aren't behaving as expected during calculations. The issue is often related to the casting of decimals as strings instead of numbers. In this comprehensive blog post, we will explain why this happens and provide a step-by-step solution to resolve the problem.Understanding the Issue
First, let's analyze the situation by considering three key aspects: Eloquent castings, decimals, and MySQL data types. 1. Eloquent Casting: Laravel's Eloquent ORM automatically converts database values to appropriate PHP types when retrieving them from the database. As a result, it might convert decimals into strings or integers based on the field type. 2. Decimal Fields: In MySQL, the "decimal" data type is designed specifically for storing monetary values with both a whole number and decimal part. It allows you to specify the maximum number of digits after the decimal point (e.g., 10,2 in decimal(10,2)). 3. MySQL Data Types: The "decimal" data type is distinct from the string data type, with its own set of rules for storing and handling numeric values. Laravel's Eloquent ORM respects these differences when working with database data.Identifying the Problem
You might be using a decimal field to store monetary values in your Eloquent model. However, when attempting to add or subtract a number from this field, you notice that the value is converted to a string representation (e.g., "1245114.00"). This issue can occur due to a mismatch between the Laravel Eloquent casting rules and how MySQL handles decimal fields.Solution: Implementing the CastsArray Trait
To fix this problem, you can use Laravel's CastsArray trait. This trait allows you to define custom casts for your Eloquent model attributes, ensuring that they are handled correctly by the database and application code. Here's a step-by-step guide on implementing the CastsArray trait: 1. Define Your Model Attribute Casts: To ensure accurate handling of decimal fields, add the following code to your model class within the casts method.protected $casts = [
'decimal_field' => 'decimal:10,2',
];
This specifies that the "decimal_field" attribute should be cast as a MySQL decimal with a maximum of 10 digits and 2 decimal places.
2. Register Your Model with Laravel: In the application's bootstrap file, add the following code to ensure your model gets registered correctly.
App::register(new App\Providers\AppServiceProvider);
3. Create a Custom Casting Rule for Decimals: To make sure Laravel understands how to handle decimals properly during Eloquent casting, you'll need to create a custom CastDecimals trait and register it as well. This trait will include logic to convert decimal strings into PHP numeric values during Eloquent castings.