Original subtitles

Now before we start fetching data,

let's have a look at the alternative,

of putting all that side effect logic

into our component.

That is perfectly fine,

but we learned that it's only one

of the two options.

The other option would be the usage

of an action creator.

And that's something we haven't done up

to this point.

Or actually we kind of did.

We are using action creators all the time.

Something like this here,

is an action creator.

We get those action creators automatically

by Redux toolkit.

And we call them,

to create the action objects which we dispatch.

So these are these automatically created action creators.

Now we can also write our own action creators

and we can write them

to create so-called thunks.

Now what is a thunk?

And why might we want to do that?

A thunk is simply a function,

that delays an action until later,

until something else finished.

And we could write an action creator as a thunk,

to write an action creator,

which does not immediately return the action object,

but which instead,

returns another function

which eventually returns the action.

So that we can run some other code

before we then dispatch the actual action object

that we did want to create.

This might sound cryptic,

but that's a very common pattern

and it is easy to implement.

So let me show you how it would work.

And let's dive into these custom action creators,

into these action creator thunks

by moving that code

for sending carts data,

out of the component,

though it would be fine there,

but to show the alternative,

let's move it out of there,

and let's move it into an action creator.

Now for this, I'll go to cart slice,

because I wanna write this custom action creator

in that same file,

because that is my file

for managing the cart.

Now to create our own action creator,

we can go to the end

of that file,

after this slice, that's important.

So outside of this slice object,

and there we can create a new function.

Let's maybe name it, send carts data.

Now that is a regular function,

and therefore, of course,

as always you could create it

with the function keyword as well.

And here let's say we expect the carts data.

Now we could write this

as a action creator,

by now returning an action object in here.

So object with a type of, whatever,

and maybe some payload.

We never did this ourselves,

because Redux toolkit,

creates these action creators automatically for us,

for all those reducer methods.

Every method in the reducers object,

receives such an action creator,

which is called,

by using that reducer function name.

That's what's inside

of these actions here.

So we don't need to write,

such simple action creators on our own.

But we could create,

action creator which does not return,

such a action object here,

but which instead returns another function.

And of course in JavaScript,

you can write functions

that return other functions.

Now that would be a function

that should receive the dispatch function

as a argument.

And we'll see where this is coming

from in a second.

And where inside of this function,

we can then therefore, dispatch,

the actual action we wanna perform.

Like for example,

showing a notification

or adding a cart item,

but before we call dispatch,

we can of course do other things,

before we call dispatch,

we can perform any asynchronous code,

any side effects,

because we will not yet,

have reached our reducer.

We're not running this code in a reducer.

It's a separate standalone JavaScript function instead.

So in our case here,

we could go to app JS,

and actually grabbed this dispatch action,

where we dispatch,

show notification, copy it,

go to the cart slice,

and execute this in here.

If were this need to get access

to the UI actions,

so I will import them,

I'll import UI actions

from UI slice, from that folder.

If we do that,

we can dispatch this action from in here.

We can then also, copy all that,

code here for sending the request

and handling the response.

And I'll not just copy it.

I'll cut it.

And I'll remove this, dispatch code

because we all did copy

to that already.

So now here we can execute this down here,

after dispatching that first notification.

Now I'm using await here.

And the great thing is,

we can convert this into async function,

this function which we returned here,

that is fine.

Now here we need the cart,

here I called it carts data.

Let me name,

let me call it card here as well,

as a parameter.

So that we do get that card

that should be sent.

Now in app JS,

we can now also grab the Abra code,

like dispatching, this action here,

go to cart slice and dispatch.

That if we make it past this, if check,

and now when it comes

to handling the potential errors,

I will actually create a new function,

send request here,

which is async,

and put my code

or sending the response

and handling the response

for sending the request

and handling the response,

inside of this function,

so that I can,

call, send request here,

and await that as well,

because it's a async function.

It returns a promise.

And since we're still inside

of this outer function,

where we also use async,

we can use await here as well.

And I know that it's quite some nesting of functions,

but this extra nesting here is required

because of how to fetch API works.

Because now we can,

wrap, try catch around this,

await block here,

and catch any errors

that might be frozen from in,

from anywhere inside of this function.

And then dispatch our error

and notification as well.

So here all, first of all,

dispatch, success ends out

of the try block if this succeeds,

but if we make it

into this catch block instead,

I wanna dispatch,

this error case instead.

So we'll copy that

into this catch block.

So with that what we're doing,

is we're creating a function,

send carts data,

which immediately, without doing anything else,

returns another function,

a async function.

We don't know yet who will execute that function,

but we will soon to know it.

But in that function,

we then dispatch a notification, action.

Then we create a new function,

so yet a never nested function,

which we create on the fly,

which has also async,

in there we send the request.

This function is then called by us,

instead of try-catch,

simply to handle any errors.

If we don't have an error,

we dispatch the success notification.

If we do have an error,

we dispatch the error notification.

So now we created this sent carts data function.

How do we now call

that function and where.

We could of course call it

from inside a component,

but that's not the idea.

Instead in app JS in there,

I will clean up the content

and use effect.

I'll keep, you could use effect though

but I'll clean up all the code in there,

and I'll get rid

of my UI actions import.

I actually will keep that,

is initial code though,

where I return

and set his initial to false.

I'll keep that.

But other than that,

I cleaned this up,

because now I wanna do something

which might look weird at first.

I wanna use sent carts data

as a action creator.

So in app JS, I still wanna dispatch,

after this initial check,

and I wanna dispatch,

this send carts data,

action so to say.

Therefore I'll export it in cart slice,

and then app JS hold an import.

I'll import, send cart data

so that function which we just exported,

from store cart slice,

from that file.

And then here use effect,

I dispatch sent cart data,

and I'll execute it

and pass my cart as an argument.

Now this might look weird.

What we dispatched before,

always were action creators.

So functions that return an action object

with a type and so on.

Now in cart slice,

we are instead dispatching a function

that returns another function.

But the great thing about Redux,

when using Redux toolkit,

is that it's prepared for that.

It does not just accept action objects

with a type property.

Instead it also does accept,

action creators that return functions.

And if it sees,

that you're dispatching,

a action which is actually a function,

instead of action object,

it will execute

that function for you.

So Redux will execute

that function for you.

And with that function,

I mean this function here,

it will give us

that dispatch argument automatically.

So that in that executed function,

we can dispatch again,

because there's a such a common pattern

that we wanna have action creators

that can perform side effects.

And that can then dispatch Abra actions,

which eventually reached the reducers,

as part of a flow off side-effects,

or as a flow of steps

that should be taken.

And that's what we have here.

So we can use a function

that returns another function,

as a action as well.

That is built into Redux

when using Redux toolkit.

So this patching this here will work.

And when we dispatch,

Redux will go ahead,

and it will execute this function for us.

And therefore all our other actions will be dispatched,

and the HTTP request will be sent.

So if you save all of that,

if we reload here,

if I add something to my cart,

it works just as before,

that still works and firebase,

the staff were still being hit,

and all the data,

is still being stored in there.

That still works,

because that is a support

that pattern by Redux.

And why would we wanna use that pattern?

Well, it's simply an alternative

to having that logic in your component.

You can add that logic in your components.

You can stick to the approach we had before,

but it's also not a bad idea

to keep your components lean,

to not have too much logic in them.

And at the moment,

by moving that logic

to this action creator function,

we did achieve this.

This component is now leaner.

It only dispatches one action,

not multiple actions.

It doesn't care

about sending the HTTP request,

and all the hard work,

happens inside of our custom action creator function,

in our Redux files.

And splitting our recode like this,

could be considered good,

because it keeps our components lean.

That does not mean

that the other approach is bad.

Both options are viable

and that's why I am showing both here.