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Hey guys going on this is Caleb with Dev's Loeb's dot com.

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And in this video we're going to write a function that's going to save our data for our goal to core

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data to our persistent store and we're going to dismiss bact goals.

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VC K open your X code project and we're going to go ahead and do this.

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Now open up finished goal visi.

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And here is where the magic's going to happen.

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Right here is create gold button was pressed.

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This is what we're going to save all of our things that we've passed.

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We've passed in a gold description from Kriegel VC we've passed in a gold type and we've also set a

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number of points in our points textfield K. That's really cool.

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Now there's one thing we forgot.

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Actually we have a back button that we did not yet set up so tap on main story board open up the assistant

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editor and make some room and right beneath create gold button was pressed.

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Go ahead and drop an Iby action called back button was pressed and just like before.

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Here's what we're going to do.

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We're going to type dismiss detail and it's going to dismiss back to the previous view controller.

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Just like a navigation controller.

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OK.

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So sorry.

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Let's move on back to what we were going to talk about before I realized that we forgot the back button

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and we're actually going to add a function called Save and this is going to utilize core data to pass

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in an object into the managed object context and save it in our persistent store.

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So go ahead and import core data to begin with.

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And we're going to go ahead and write this function now so you know what.

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Let me give you some more room here so you can see everything.

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There we go.

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All right.

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So go ahead and type phunk save and that is going to be the name of our function but we need to know

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when saving is complete when it's finished when it's not.

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Because if it does finish successfully we want to dismiss the view controller if it doesn't we want

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to at least print an error to the console for now.

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So we're going to go ahead and build a completion handler which is basically a function that we can

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pass a value to and whenever we call this function we can get that value wherever we call this function.

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So go ahead and type completion and we're going to go ahead and inside of our bracket here we're going

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to make a function.

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OK.

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And it's going to to first take a parameter called Finished of type bool and this function is going

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to return an empty function cause we don't care what it returns at the end.

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We just need to be able to pass in a value here and at the end it's going to return this value to us.

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OK.

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So that's our completion handler.

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And what we're going to do now is we're going to go ahead and set up the managed object context in the

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what is core data video.

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I told you that you would be interacting the most with the managed object context so we're going to

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go ahead and create this now.

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But before we do that we need to create an instance of our app delegate because when we create a project

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with core data if you scroll down to the bottom you'll see that there is a lot of interesting things

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in here from your core data stack.

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We have a persistent container we have a function that lets us save the current context.

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There's stuff for core data built right in.

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And it does that for us which is incredibly helpful but we need to go to two goals Fisi and we're going

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to create a constant that is accessible publicly across all of our controllers by writing it outside

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of the class.

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So go ahead and type let app delegate equals UI application shared application or shared delegate.

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OK that gets our apt delegate but we're going to optionally cast it as type app delegate.

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OK so there's are app delegate We now can access that from anywhere.

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And we're going to use that now in our Save function in order to get our managed object context.

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OK.

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So go ahead and type guard let managed context.

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And we're going to set that to be equal to the app delegate the one with the lowercase a persistent

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container view context.

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OK.

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This is how we get our managed object context from the main queue it's the one that's associated with

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the main queue it's our main managed object context OK.

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Now if we can't get that for some reason we're going to just go ahead and call.

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Else return.

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Because if we can't get this we should not move forward.

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Now what we're going to do is we're going to create an instance of goal an instance of goal meaning

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our goal model our goal entity from core data.

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So go back and tickle a finished goal VC and type let goal.

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And remember we can just type goal as if it was a swift class super super cool.

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And in order to this properly we need to tell the managed object context which model it's going to be

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using in order to create the persistent storage coordinator.

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So put a print next to it and you'll see we can pass in a context press enter and pass in the managed

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context.

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Supercool.

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So now we have created an instance of goal and we've given it a managed context that it needs to know

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so that it knows where it's saving the data so that it can be properly managed.

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Very very cool.

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Now believe it or not we can use this just like any other swift class we can call goal and now we can

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set all four of these properties.

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We've already passed in a goal description and initialize that when this view controller is created.

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So go ahead and just type goal goal description and set that to be equal to goal description.

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The one from this view controller.

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Next go ahead and type goal dot goal type and we can also pass the goal type from this view controller.

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Next we have goal dot goal completion value.

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We can set that to be equal to the textfield right points textfield tells us how many we have.

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So we can go ahead and type points textfield text and unwrap it right because it's coming from a textfield

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which has an optional string but it's giving us an error cannot assign value of type String type into

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32.

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Remember that inside of our goal it's what we need to look at here.

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We're saving goal completion value as an in 32.

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So what we're going to actually need to do is cast this as an in 32.

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So I'm going to put it in parentheses and at the beginning I'm going to go ahead and type and 32 and

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that will cast it as an in 32 value.

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So whatever is inside the text field we're saying this is a number and we know it can only be a number

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because we have set the number pad.

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Now in order to properly forecast this we need to unwrap it at the end so just do that.

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But we know for sure that the number value which will be an integer we can cast as an in 32.

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Now remember gold type in and of itself is what type.

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Can't remember gold type.

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OK.

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So gold type has an inherent value of string but we need to pull out the raw value to actually access

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that as you can tell the raw value of the raw type is string.

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So in order to set the goal type we need to set the raw value because Chordata cannot accept gold type

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as as a type.

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OK.

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So then what we're going to do is we're going to set goal goal progress like so.

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Now if you saw gold progress is 32 as well.

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When we create our goal we have made zero progress on that goal.

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So we should call in 32 and we should give it a value of zero.

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Okay we're going to set in 32 of 0 as our goal progress that's how we're initially starting out is at

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zero.

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Pretty cool.

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So this is great.

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And we have set this but we have not yet told the managed object context to pass this into persistent

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storage.

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We have simply set up a model.

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So in order to do that we're going to go ahead and call managed context that's safe.

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Now you'll notice it says throes.

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Right.

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And that is where we're actually going to need to use a do catch block K because we can say do meaning

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do this try to save the Manage context and then we can call catch meaning if there's an error.

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We're going to catch it.

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And in order to print out the error we're going to use Debug print and debug print writes the textual

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representation of the given items most suitable for debugging into the standard output.

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It just helps us out.

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So debug print and we're going to say could not save.

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And we'll just print out the error that is thrown.

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Like so.

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Well of course this needs to be a string.

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So the error that's thrown is here but we should definitely print out the localized description because

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that will give us kind of a plain English version of the error.

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So awesome.

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This is great.

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But in order to actually successfully try this we need to call try.

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OK.

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We're going to use do try to save our context if it doesn't work.

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We're going to catch the error and we're going to print it here so that we know what's going on.

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Now this is great and all but we need to be able to tell our completion handler when we're done.

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So if saving happens properly we're going to go ahead and call completion and pass it.

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True if it doesn't work properly it's going to print out and we're going to call completion false.

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OK.

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So that's pretty cool.

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We're telling it we're good.

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We're complete or we're saying we're not complete we didn't finish.

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So this is how we're going to save to Chordata K supercool we're using our managed object text we're

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creating a managed object model and we're using save in order to commit unsaved changes to the context

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parents store right which if you look here is the persistent store coordinator.

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Very very cool.

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So now we need to think about where we're going to save this create Go button was pressed.

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Let's do it.

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So we're going to call self save and the completion block we're going to set as.

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How about complete.

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So we can save all of our data is here we're going to say if it's complete ok if it's finished we're

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going to go ahead and dismiss.

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And we're going to say true.

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And the completion will be nil.

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So we're not using our fancy dismissal we're just going to dismiss all the way to the main view controller.

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Now there's one thing that I want you to think about here.

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What if we have not yet typed anything in point textfield that's going to cause some problems.

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So we need to verify that we have actually type something before we can even create this goal.

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So go ahead and type if points textfield text is not equal to nil.

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We're going to call self-direct save.

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All right.

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So pass that in there and let's go see if this works let's try it and if we get an error we'll know

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it did not work.

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You know what how about this.

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If it does work let's just print successfully.

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Oops.

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Fully saved data so we can just check to see if we're good to go.

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And if it properly dismisses.

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Build and run and our simulator will come up here.

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Let's go ahead and yeah let's pop open that view controller eat salad twice.

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That's a short term goal let's say that this will be done in two salads and create a goal OK successfully

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save data and dismissed but look at this it's still showing our previous view controller that is not

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at all what we want.

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So we're going to need to fix that but let's do that in the next video.

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Then after that we're going to go ahead and write our function to fetch all this data from our core

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data data model.

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Super duper cool.

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Awesome job guys.

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We will fix that dismissal in the next video.

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Great job with this one.

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Acia there.