yii2 string validation using substr() in comparing attributes of two related model - arrays

Question

I have this two table:
Region table
create table if not exists Region (
id int(2) unsigned not null auto_increment,
name varchar(40) unique not null,
code varchar(9) not null,
primary key(id)
);
Province table:
create table if not exists Province (
id int(2) unsigned not null auto_increment,
region_id int(2) unsigned not null,
name varchar(40) unique not null,
code varchar(9) not null,
primary key(id),
key region_id(region_id),
constraint province_region_id foreign key(region_id) references region(id)
);
sample data:
region_code: 010000000
province_code: 010100000
they are related coz they have the same first two character
ive created a partial custom validation but i cant finish it and even don't know if using substr() with arrayhelper combination is okay
public function modelCodeValidator()
{
$regCode=>substr([Arrayhelper::map(Region::find()->all()->,'id','code')],2);// specifying first two character of region.code
$provCode=>substr('code',2);//specifying first two character of province.code
return [$regCode=$provCode];
}
on this custom validation, rule() would be:
['code','compare','modelCodeValidator' don't know next]
first two character of region_code should match/equal to the first two character of province_code. by doing this user will notified that they could only enterered province code belonging to a particular region.please help

Answer 1

Try by something like this..
public function rules()
{
return [
['code', 'modelCodeValidator'],
];
}
public function modelCodeValidator($attribute, $params)
{
// Write your coding stuff here
if (YourModelName::findOne(['your_model_field'=> $attribute]) {
$this->addError($attribute, \Yii::t('view', 'The fields don't match.'));
}
}
take a look here :->
http://www.yiiframework.com/doc-2.0/guide-input-validation.html#client-side-validation