This is something that is already possible using validation groups. I am not convinced that we need yet another way to achieve the same.

I know we can use validation groups, but I am always trying to avoid to use them.
I don't really like the way they work. We cannot know what are the required conditions for a validation group to be used just by looking at them. We need to find in the code where they are used to understand their purpose.

If I take another example:
A form providing a subject select dropdown with an other choice.
If the other choice is selected, the subject_other text field become required and must be NotBlank.

Using validation groups, this means we have to set up validation groups based on submitted data in every forms we are using the fields.

With the suggested feature, we just need to add a condition on a NotBlank constraint attached to the subject_other field and it's done.

It's just more or less the same as using an Expression constraint.

I like the idea, but, as a workaround i created a custom constraint to do it.

@AppAssert\IfThen(condition="this.getFoo()", constraints={@Assert\NotBlank()})

@Seb33300 , indeed, groups are often appear to be cumbersome.

Agree with @felipyamorim , composition of constraints is a much better idea than an option in every single constraint. Made a similar one back in the days, see https://gist.github.com/vudaltsov/8e652c122e2344ce8574635b5514a975.

I think I will do a package for this with a couple of other usefull composition constraints. And then we'll see if it makes sense in the core.

@vudaltsov it would be great to see this in the core.

I have a price object and want it to be valid if value property is not empty. I think it's a common practice to work with "empty" object and it's easily solved with your Condition constraint.

/**
 * @var PriceModel
 *
 * @Condition("this.price and this.price.value", {
 *      @Assert\Valid()
 * })
 */
public $price;

Correct me if I'm wrong but looks like it's impossible to solve this with validation group

I have a price object and want it to be valid if value property is not empty.

Your constraints should have this logic inside of them and not extracted as a parameter..

I found another situation where this feature request can help. At first, I thought like @xabbuh , groups are enough. Especially if you consider this: If residence country == 'BE', national registration number is required

Simple right?

class Person {

/** @NotBlank(groups=["BE"]) */
public $nationalRegistrationNumber;

}

$validator->validate($data, null, $data['country'] == 'BE' ? ['BE'] : []);

This is fine.

But, how would you implement this: if country <> 'BE', passport is required

I can array_filter(Country::all(), function($country) use ($excludedCountries) { return $country not in ... But yeah, the proposal seems legit to me :D

I like the proposal from #32877 (comment). The advantage is being able to have this in a different package first as suggested in #32877 (comment) thus being able to evaluate first if it proves useful.

Thank you for this suggestion.
There has not been a lot of activity here for a while. Would you still like to see this feature?

Friendly reminder that this issue exists. If I don't hear anything I'll close this.

Let's close here for now. We can consider to reopen once there is a well-working third-party solution that could be integrated.

Isn't @vudaltsov idea (see his gist) worth a PR?
Seems simple and powerful.