All language subtitles for 014 Creating a Global Key_en

In the last section, we spoke about how we need to create a global key and somehow reference it or

get it to reference our form state that is created and each time we create a form widget, again, I

know this stuff is kind of heavy duty, kind of complicated, but as soon as we start writing some code,

I think you'll start to get an idea of what's going on.

So let's write some code.

I'm going to begin by looking back over to my code editor and I'm going to find my login screen state

class.

So inside, if you're going to create a new instance variable that's going to store that global key.

So I'm going to make a final variable which remembers just means I cannot reassign this variable.

I'm going to call it form key because it's referencing the form into it, I'm going to assign global

key and then this thing uses that same generic syntax that we use for state up here.

Remember, these generic open closing little brackets are a way to kind of create a constructor or a

class that accepts a type almost like a function.

So we put a type inside of here and that customizes how all the functions inside of it behave, or at

least what different types they expect.

So to the global key, we do not want to reference the form class, we want to reference a class called

Form State.

So for the type here, I'm going to put in form state like so, and then I'm going to put myself in

parentheses to indicate that I want to create an instance of this global key thing.

OK, so this right here is just about the only place we're going to see this form state thing come into

play.

That's why I had to tell you about the existence of this form state, because at some point we had to,

like, write out Farm State right here.

If we just wrote form state, you probably would have been like, Stephen, why are we writing for state

and not just farm?

OK, so this creates the key.

Now, step two is to take this key and associated with the form widget that we are creating.

So on my form widget as an additional named property, I'm going to pass in key and key is going to

be the form key instance variable that we just created.

So I'm going to say form key like so.

And that's pretty much it.