Laravel string validation to allow empty strings

Question

In Laravel 5.7 I am using form request validation:

public function rules() 
{
    return [
        'age' => 'integer',
        'title' => 'string|max:50'
    ];
}

If I submit a request to my API with this payload:

{
  "age": 24,
  "title": ""
}

Laravel returns the error:

{
    "message": "The given data was invalid.",
    "errors": {
        "title": [
            "The title must be a string."
        ]
    }
}

I would expect it to pass the validation, since the title is a string, albeit an empty one. How should the validation be formulated to allow empty strings?

@ka_lin Present and required do not describe this property, which doesn't need to be present and is not required. — GluePear
– GluePear, Commented Feb 22, 2019 at 15:41

Zakalwe · Accepted Answer · 2019-02-22 15:36:00Z

60

You would need nullable to allow an empty string

public function rules() 
{
    return [
        'age' => 'integer',
        'title' => 'nullable|string|max:50'
    ];
}

answered Feb 22, 2019 at 15:36

Zakalwe

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5 Comments

ka_lin Over a year ago

nullable - The field under validation may be null. This is particularly useful when validating primitive such as strings and integers that can contain null values.

GluePear Over a year ago

This doesn't allow an empty string, this simply ignores an empty string, treating it as null. What if we want to overwrite the existing title field with an empty string?

George Hanson Over a year ago

@GluePear if you wanted to do that you would also need to disable \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class from your middleware. That middleware will automatically convert empty strings to null. From a database normalisation point of view, it would be better to have null as the value rather than an empty string anyway.

Pathros Over a year ago

I confirm this does work. If you leave that specific field empty, nullable makes it pass being empty. Here are the docs.

ATG Over a year ago

Any solution in case you have $request->file('image')? Both nullable and sometimes doesn't work.

ka_lin · Accepted Answer · 2019-02-22 15:43:05Z

26

Try to see if ConvertEmptyStringsToNull middleware is active then it would explain this behavior, see docs

answered Feb 22, 2019 at 15:43

ka_lin

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1 Comment

GluePear Over a year ago

Thanks, that's useful. I'm not confident removing that middleware in case it's used elsewhere. But it explains the behaviour.

Mahdi Aslami Khavari · Accepted Answer · 2021-06-10 08:01:33Z

9

there is present rule in that check present of a key but let it to be empty.

#present

present The field under validation must be present in the input data but can be empty.

https://laravel.com/docs/5.7/validation#rule-present

answered Jun 10, 2021 at 8:01

Mahdi Aslami Khavari

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Comments

ErcanE · Accepted Answer · 2022-01-07 11:52:58Z

2

Avoid touching Middleware settings.

Instead Use Laravel build in function to manipulate data before validation runs.

Inside Validation class

protected function prepareForValidation()
    {
        if($this->title == null )
            $this->merge(['title'=>'']);
    }

answered Jan 7, 2022 at 11:52

ErcanE

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Comments

Anwar · Accepted Answer · 2022-06-22 09:27:38Z

1

The accepted answer does not fix the issue when you have this rule:

return [
  "title" => "sometimes|string",
];

In this case, you need to specifiy the string is actually "nullable" (even if the ConvertEmptyStringsToNull middleware is active, tested on Laravel 8.77.1)

So this one will allow to pass an empty string on the "title" key:

return [
  "title" => "sometimes|string|nullable",
];

answered Jun 22, 2022 at 9:27

Anwar

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Comments

Shuyi · Accepted Answer · 2019-02-22 15:57:50Z

0

I will try

public function rules() 
{
    return [
        'age' => 'integer',
        'title' => 'string|sometimes'
    ];
}

This will only validate title when it is present.

answered Feb 22, 2019 at 15:57

Shuyi

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1 Comment

PatricNox Over a year ago

Doesn't answer the problem when you want it to always be present, though allowed to be empty.

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