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And right after we set up our customer handler, let's work on our full of responses to and essentially

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I want to set up a custom class which extends from the general JavaScript class.

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And that way we can handle all of our four or four responses in our newly created error handler as well.

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And we're going to start by navigating back through the controllers and the routes or controllers that

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I'm looking for are following.

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I want to work on update task here and we send the four or four then the same is for deleting the task

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and of course, getting task.

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And let's just start over here.

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We have getting the task and simply I want to showcase that we can create a new object if we run the

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built in JavaScript error constructor and we go here with no surprise, I'm going to call this error

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and that is equal to new.

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And then we're just go with error.

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And here we pass in the message so I can say not found.

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And when the next line, I'm just going to go with error.

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So now I'm dealing with the object that I just created and I'll set another property on it and I'll

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say status.

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So that's the name of the property.

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And of course, the value will be for all four.

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So now.

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If you want, you can console it here or we can simply do is use next and pass this guy down to our

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custom, our handler.

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Remember, that's how it works.

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We call next and then we pass in the air.

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And of course, in this case, we are creating that air ourselves instead of getting it from the Mongo's.

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And the only thing that's missing right now is in our controller because we don't have the next.

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So I want to go here with next and then we need to go with return.

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Again, I already mentioned why we want to do that, because we don't want JavaScript to keep reading

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the code.

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And of course, we have this one right now.

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But hopefully you get the gist where we need to go with a return and then next and of course, I want

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to pass in my newly created error object.

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And once I do that, if we go back over here in the error handler, if we simply console log, we should

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see our newly created error object.

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So I'm going to go over here with console log and I'll look for my error and I'll let me go back to

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the postman.

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And essentially what I want to do, I want to get all the tasks.

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And then I'll look for one of the ideas, but again, I don't want to get that cast there, so I still

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want to keep the same structure.

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I just want to pass in the wrong room.

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So I'll look for a single task.

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I'll copy and paste, and then instead of three, I'm going to go with four.

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So once we send, of course, we get our custom error message, as vague as it currently is.

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And then, of course, in council, I can clearly see that I have not found.

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So of course, that is going to be my message.

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And I understand that might be a bit confusing.

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But effectively, the idea is following where once we create this new object, that property is going

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to be on there.

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So in order to access the string, value will have to go here and simply go with error.

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And then that message.

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And as far as the status, well, we can clearly see we're going to have four or four.

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So now just for kicks, what are we can do is set up message is equal to error message.

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Like I said, there's the property on an object.

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And then as far as the status, well, I can simply change this one around where instead of five hundred

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I'll pass in error and then status and the worry.

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Of course there's more code coming.

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And once I have these changes of course we can swing back to our postman and check it out.

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Now of course we have for four and the message is not found, so that's pretty cool.

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Now of course we just need to go back to the tasks and set it up in such a way where we don't have to

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do this all the time manually.

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And the idea is following where again will create a new class, a new custom class, and we'll extend

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it from the JavaScript error and then we'll create a new instance and yada, yada.

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And effectively, the way we want to do that, we want to create a new folder.

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And I'll call these errors pretty self-explanatory.

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So we're going to go here with new folders and we're going to go with errors.

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And inside of it, I'm going to create another new file.

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And in this case, I'm going to call this custom and hyphen error.

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And of course, I'm going to add the extension.

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And then inside of my custom error now I want to extend from the error class.

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Now, here's the deal.

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In this case, I'll just write out the code and then I'll go line by line of what's happening, because

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I think that's going to be a bit more productive.

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So let's go here with class and then we just need to come up with a name.

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In my case, I'm going to go with the long one.

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I'm going to say custom API.

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And now we need to use the extended keyword.

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And since I want to extend from the error class, I'm going to go here with error.

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And as far as the functionality, we want to go with constructor.

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And here I'll pass the message and status code and insert the constructor we want to call super, then

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pass in the message.

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And right after I call Super, I'm going to go with that status code.

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And I'll set that one equal to whatever I'm passing in the constructor Sauniere, I'll pass the and

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the status code.

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And as far as these few lines of code, a constructor method is a special method we invoke when we create

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a new instance of a class.

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And in our case, it will pass into arguments and our message and a status code.

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Then since we're extending basically we're setting up a child class we need to call super method, which

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in turn invokes a constructor of a parent class.

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And of course we pass in our message.

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Value, as a result will have access to all the methods and properties of the parent.

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So in our instance, we have the message probably and with this that status code, we create a status

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quo property as well.

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And that's how we can create our new custom, our class.

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And essentially, if you want to create new instances, you can simply go with custom and then appear

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and then pass in those two values the message and status code.

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But I actually like to set up a new function that does that for me.

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And here I'm going to go with const create custom and error.

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And this function is going to be looking for two parameters, a message and a status code.

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And what I'm going to do is from this function, I'm going to return that new instance, I'm going to

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go with the return new and then we're looking for a custom API error.

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And then, of course, we'll pass in the message here as well as the status code.

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Of course, if you want to keep the same parameter names, you can definitely do so.

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But in my case, I'm purposely setting this up so you can see that this is coming from the function

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as far as the message.

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And of course, I pass into my custom API or more specifically in the constructor as a message.

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And then, of course, we just need to export this and we'll have to export both of them.

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And you'll see in a second why.

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So we're going to go with module exports is equal to an object, and then we're looking for create custom

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and then custom API here.

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And once we have both, once we have the class as well as the function and we're exporting both now,

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of course, we want to go to the tasks.

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We just need to remember that, of course, we're exporting object.

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So therefore we'll have to provide a specific name.

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In our case.

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I'm looking here for the function, so I'm going to go I'll set up my Curley's and I'll say create an

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custom error.

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So of course that is my function.

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So it equal to require.

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I do need to go two levels up.

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So in here we're looking for errors and then more specifically, I'm looking for the custom one.

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And then I want to replace all of these three instances.

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And of course I want to remove this manual code as well.

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So start over here and I'll keep this one for the second just because I want to use the same message

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and the areas following where we go with our return.

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Next, and then the next we pass in create custom air, and of course, we want to pass in the message.

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So that's why I'll just copy this one just because I want to speed this up.

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And then the second thing is going to be my status quo, which, of course, is going to be four or

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four.

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And now we're going to remove the second line and we just want to copy and paste.

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So it's the same deal over here.

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And the same in the update desk as well.

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And once we have all of this in place now, we just want to go to our handler so our customer handler.

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And instead of looking for a function, we're looking for the class.

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Because in here, I want to check if the instance is equal to our customer one, then of course, I'll

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pass in the status code and the error message.

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However, if there is any other error, then of course we'll just go with the status.

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Five hundred and whatever we had before.

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So let me go at the top and I'm going to go with Consed again.

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It is name the import.

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So we're looking for custom.

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API and error, and that is equal to require and same deal we go to levels up.

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We're looking for errors and more specifically, custom error.

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And let's write or set up the default one.

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And this one, I'll set it back to five hundred here.

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And then as far as the JSON, let's go with the same message.

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I'm just going to say something went wrong.

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Please try again.

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And above this return, we're going to go with if and then we'll check if the error is the instance

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of our custom API error that of course, I want to go with a return and I want to pass in the resident

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status.

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And that will be equal to a error, that status code, because, of course, that's where the value

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is sitting in that property.

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And when it comes to the actual message saying, deal, I'm going to go with a message and this one

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will be equal to error.

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And then we're looking for the message property.

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And once we save, let's go and test it out.

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Or essentially, if I send it here from the postman, of course, I'll have no task with of this idea.

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And if I'm going to mess with the syntax I should get the faster.

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Of course I do, because I can clearly see that something went wrong.

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Please try again.

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Lastly, let me just repeat one more time.

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But error handling and validation is something we're going to return to later, most likely in a separate

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project.

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This is just a general setup just to get you comfortable with overall ideas and later work on more complex

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validation and error handling approach.