Version 3, is customized validation supported?

[jasonlaw]

Hi @danvick , does version 3 still support for custom validator?
Suppose I have a text field with some customize validation, can it still be done now?

[danvick]

Ooh yeah. The fields have an attribute named validators which takes a list of FormFieldValidators. That makes validators composable and reusable. There is a class named FormBuilderValidators with all the common validators but you can definitely include your own custom validator.
Checkout the v3 example (on pub).
Sample Usage:

FormBuilderTextField(
    attribute: "age",
    decoration: InputDecoration(labelText: "Age"),
    validators: [
        FormBuilderValidators.numeric(),
        FormBuilderValidators.max(70)
        FormBuilderValidators.min(18, errorText: "You can't be under 18.")
    ],
),

P.S. I'm currently working on comprehensive documentation.

[jasonlaw]

That means we can create our own customized FormBuilderValidator right?

[danvick]

Sure. Or alternatively just stick in your validator function inside the list of validators, like so:

FormBuilderTextField(
    attribute: "over_18",
    decoration: InputDecoration(labelText: "Are you over 18?"),
    validators: [
        FormBuilderValidators.required(),
        (val){
            if(val != "Yes")
                return "The answer must be Yes";
        },
    ],
),

[danvick]

The validator function just has to be of type FormFieldValidator from Flutter. The reason for making it this way - in a list - is to allow you to define your custom validator once and just use it in different fields or even across multiple forms / pages.

[jasonlaw]

I see, that's cool....great job! Thank you very much!

[danvick]

I'm glad you appreciate it.