Laravel 12 Validation Rule Sometimes vs Nullable

In this laravel tutorial titled “Laravel 12 Validation Rule Sometimes vs Nullable” Use sometimes for optional, heavy fields (like file uploads) to avoid wasting resources.

Use nullable for lighter fields (like strings, numbers) where performance impact is minimal., you we’ll learn the differences between sometimes and nullable in Laravel 12, provide practical examples, and show you when to use each rule.

When building Laravel applications, proper validation is crucial for data integrity and user experience. Two commonly confused validation rules are sometimes and nullable. While both make fields optional in different ways, understanding their distinct behaviors will help you choose the right one for your specific use case.

Core Difference

The fundamental difference lies in when the validation rules are applied:

• sometimes: Validates only if the field is present in the request
• nullable: Always validates but allows null values

Let’s break this down with clear examples.

Read Also : Laravel 12 Conditional Validation required_if,nullable And More

sometimes Validation Rule

sometimes rule acts as a conditional guard. It tells Laravel: “Only apply the validation rules if this field exists in the request data”.

Basic Syntax

'field_name' => 'sometimes|other_rules'

Key Characteristics

• Field is completely optional
• Field is exists in the request validation rules apply
• Field is missing from the request no validation occurs
• Does not allow null unless combined with nullable
• Perfect for partial updates and optional API parameters

Example:

$validate = $request->validate([
            'username' => 'required|string',
            'email' => 'required|string|email',
            'avatar' => 'sometimes|image|max:2048',
            
        ]);

Explanation

• If avatar is not sent in the request, no validation occurs
• If avatar is present (even empty), it must pass the required and other rules

Read Also : Laravel 12 Custom Validation Rule with Parameters

nullable Validation Rule

The nullable rule allows a field to be null or empty while still being validated when present with actual values.

Basic Syntax

'field_name' => 'nullable|other_rules'

Key Characteristics

• Field must exist in the request
• Can be null or empty string (“”)
• Other validation rules are skipped if value is null or empty
• Must be used when you want optional fields with conditional validation

Example 1: Simple Example

Suppose we have a form with an optional phone_number field. If the user enters it, we need to validate it as a 10-digit number.

$request->validate([
    'phone_number' => 'nullable|digits:10',
]);

Explanation

• If phone_number is not provided, no error will occur.
• If phone_number is provided, it must be exactly 10 digits.

Example 2: Conditional Validation Based on Another Field

$request->validate([
    'email' => 'required_without:phone|nullable|string|email',
    'phone' => 'required_without:email|nullable|digits:10',
]);

Explanation

• Either email or phone must be filled.
• Email depends on phone if phone is missing, email becomes required.
• Phone depends on email if email is missing, phone becomes required.
• nullable ensures the dependent field can be empty safely without triggering other rules.
• If email is provided must be a valid string and email.
• If phone is provided must be 10 digits.

Example 3: Validation Based on a Specific Condition

$request->validate([
                'state'   => 'required | numeric',
                'district'=>'required_if:state,1 |nullable | numeric',
            ]); 

Explanation

• state is always required and must be numeric.
• district is required only when state = 1, otherwise it can be null.

This is a specific condition validation: the rule applies only when a particular condition (state = 1) is met.

Common Errors to Avoid

1. Forgetting Laravel’s TrimStrings and ConvertEmptyStringsToNull middleware

Laravel’s TrimStrings middleware any request sent will trim by trimstring middleware and ConvertEmptyStringsToNull middleware automatically converts empty strings to null. This affects how nullable works:

// With ConvertEmptyStringsToNull middleware active
$request->validate([
    'description' => 'nullable|string|max:500'
]);

// Empty string "" becomes null and passes validation

2. Using required with sometimes

//  Problematic
'password' => 'sometimes|required|min:8'
//  Better approach
'password' => 'sometimes|nullable|min:8'

• sometimes only validate if the field is present in the request.
• But when it is present, required forces it to be non-empty.
• So, if you send password => “” (empty string), it fails with “The password field is required.”

Best Practice: Combining Rules

public function rules()
{
    return [
        // Field is optional, but if present and not null, validate
        'website' => 'sometimes|nullable|url',
        
        // Field must be present, but can be null
        'description' => 'nullable|string|max:1000',
        
        // Field is completely optional
        'avatar' => 'sometimes|image|max:2048',
        
        // Conditional requirement
        'company_name' => 'required_if:account_type,business|nullable|string|max:255',
    ];
}

• website: sometimes + nullable field is optional; validate only if present and not empty.
• description : nullable alone field can be empty, but validation rules run if a value exists.
• company_name: required_if + nullable field is required only under a condition, otherwise optional.
• Combining rules gives fine-grained control over optional and conditional fields.

Performance Considerations

Using sometimes for Better Performance

//  Efficient - only validates when field is present
'large_file' => 'sometimes|file|max:10240|mimes:pdf,doc,docx'

// Less efficient - always checks file rules even when not uploaded
'large_file' => 'nullable|file|max:10240|mimes:pdf,doc,docx'

• sometimes skip validation if missing better for performance.
• nullable always validate, even if empty less efficient for big fields like files.
• Use sometimes for optional, heavy fields (like file uploads) to avoid wasting resources.
• Use nullable for lighter fields (like strings, numbers) where performance impact is minimal.

When to Use Which Rule

Conclusion

Understanding the difference between sometimes and nullable is crucial for building robust Laravel applications:

• Use sometimes when you want to validate a field only if it’s present in the request
  Use nullable when a field can be empty/null but should be validated when it has a value
  Combine both rules when you need maximum flexibility: ‘field’ => ‘sometimes|nullable|string’

The key is matching your validation strategy to your application’s data flow and user experience requirements. By choosing the right validation rules, you’ll create more intuitive forms and APIs that handle edge cases gracefully.