Laravel 5.4 add a message to validator's errors - php

Question

So I am receiving data from a form that should reset user passwords:
Old Password: |field|
New Password: |field|
Confirm Password: |field|
And i want to be able to display a message out for the user if his old password does not match what he entered in the first field. I don't want to make an entirely new validation method and just want to throw an error to the use when i make my own if(). So how do I achieve this using the $errors variable that is available in my blade views
So here is an example of my controllers method
public function update(Request $request){
$this->validate($request,[
'oldPassword' => 'required',
'password' => 'required|min:8|confirmed'
]);
$user = Auth::user();
if(password_verify($request->newPass,$user->password)){
$user = User::find($user->id);
$user->password = bcrypt($request->newPass);
$user->save();
}else{
//the code for adding a new key to $errors variable
return back(); Or return redirect('path');
}
}
So in the view I want to this
#if (count($errors) > 0)
<div class="alert alert-danger">
<ul>
#foreach ($errors->all() as $error)
<li>{{ $error }}</li>
#endforeach
</ul>
</div>
#endif

Answer 1

You can do this in your controller:
$validator = Validator::make($request->all(),[
'oldPassword' => 'required',
'password' => 'required|min:8|confirmed'
]);
And then before your return back();, add:
$validator->after(function($validator) {
$validator->errors()->add('tagName', 'Error message');
});
With your message.