Summary of Getting Started with Express: Deleting a Book

Welcome back to Getting Started with Express. So we did get all the books, a book by ID, create a book, update a book. Now the only thing remaining is deleting a book. That's what we're going to do in this lesson. So let's get started. The HP verb is going to be delete. And then we're going to do slash books slash book ID for the endpoint. Now delete is pretty easy because all you need is the book ID and don't need a body. You're just going to find a book and delete it. Okay, so let's go back to our app. And right after let's see food, right after put right here, let's do app dot delete. Okay, and we're just going to follow the same pattern as we did before. So I want to challenge you to try to do the delete by yourself before we can move on. So how did it go? So let's try it. We're gonna do slash books slash colon book ID, rec rest. And then we need to go color book dot what we don't have it yet. So let's call it this try. So we need the ID of the book to destroy and that's in rec dot programs dot book ID, but we need to parse it. So let's do it. book ID. Let's parse int the rec dot per oops, rec dot programs dot book ID. And use base 10. After that, we pass it to the destroy method that so you have to be defined, that guy's going to remove it and that's pretty much it. Just it should return actually, what should it return, maybe just the ID of the book that was returned, something like that, because we what if we try to destroy something that does not exist? Should this guy return no, I guess so. Actually, we should just first find the book and to see if it exists. And then after that, we try to destroy it. So destroy is just going to return the ID of the book that was destroyed if it succeeds, otherwise it should do no. So let's just find the book first. We're going to do book dot find one. The ID is book ID, constant book, like so remember, the fine one. Now, if I want to find one and then I want to check if the book does not exist, then we don't need to delete it, right? We should do a 404. How about that? We're going to say rest dot send status 404. And just that same message we had before, let me copy it. Exactly, except it's the book you want to delete does not exist. Okay, so do a return right here so it does not go on to the next things we want to do. So we look for the book first, if it does not exist return 404 otherwise we can proceed to destroy it because it exists, right? And then after destroying it, we just want to check if destroyed book ID is that. So if the book ID matched the destroyed book ID, something like this, so we can have a, we can know it actually destroyed it, or you could just check if this guy is no actually. Yeah, let's try that if destroyed book ID is not no. And that means it actually destroyed it that we have defined yet, we should raise rest dot send. We just send nothing actually, we can just the status 201 meaning empty, like success. And that's pretty much it. Let's do a send status. We don't have to return anything if we delete it successfully just 201. Now what happens if you forget to return here if the destroyed book fails, right? We don't have any mechanism to check for errors right now because we're just doing the hard-booted ORM like thing. So I would say just return some kind of error right here at the end in case this does not match. So I know it's getting a little bit complicated and even though it's supposed to be easy. Anyway, there's so error handle you have to think about it. I just want you to get get started to thinking about how to handle these special cases. It makes a little bit more complicated in any case. So if it happens so that the destroyed book ID, you didn't get anything you got null because the operation to destroy failed, then you should definitely send back a rest dot status or I don't know specific error you should be able to do right here. Maybe let's do a 500 and you a general internal server error. And just like that, a message could not destroy, oops, could not delete the book. I've liked that. Anyway, our case, this is not not going to fail I hope because we're already checked the book exists and everything, but it's just in case. Anyway, so let's define this book that destroyed right here. So down there destroy in the book.js file, we need the ID of the book to destroy. All we have to do is go through the list and eliminate the ones we find right. So we can go and use filter. It's a method of the array prototype. So we filter out the guys that do not match the ID of the item we want to delete. So we're going to do the following books, it's going to be equals to books about filter book. So we're going to allow all the book whose IDs are is not the ID of the book to be destroyed. This is going to filter allow every book to be in the new list except for the one that matches the desired ID. Okay, so you're telling it please include the book as long as its ID is not the one that I'm looking for. To do that or database is updated and we don't have to do anything, we just return the ID back. Now if there somehow if we're working with an ORM or whatever, in a given error, you would have to handle it here and return no sum to indicate there was a problem or something anyway, we're not dealing with that. So going back to our app.js, let's see what we have here. Let's test it out. Save this postman. Let's change the delete. Let's delete book four. Well, the book you want to delete does not exist because we implemented that, right? Now let's delete book number one. Created. Oops, 201 created. I think I've got the wrong code. I think it should be 204, I'm sorry. Let me just do a quick search right here. 204 code. Yeah, that's it. I'm sorry. That was not 201. It was supposed to be 204, no content. Okay, so let me fix that. I meant to be 204 if you successfully destroy a book because there's no content, we just send the status code. In any case, let's get back to what we were doing. Let's do a get all books. We have one, two and three. Remember the server restarted. So that's why we have them. Let's delete the first one. I'm going to delete books one. I don't need a body data right now. So don't need you ignore that. So delete the first one. We got a 204 no content with nothing. Let's check the database. Okay, one is gone. Let's do three. Delete three, no content. Three is gone. Let's do want to to remove the last one. Delete book slash two. Oops, what happened here? Oh, maybe there was a problem in your database or not. Could not get any response. Oh, I don't know what I have. Anyway, let's check the database. There's nothing now. Okay, so that's it. No problems here. We're all good. Let's review what we did. This lesson we learned how to destroy or delete an existing resource, or if it does not exist, we do 404. So first we have to parse the book ID from the rack parameters, the route parameters. First we look, then we looked for the book to see if it actually exists. If it does not exist, return a 404 status with a message error as the error, error message. We all then we call booked up destroy of the book ID and everything goes well. We know it's going to go well in our case because it was hard coded data without any promises or async, async operations. And we if we got the ID, which we probably we're always going to get in this case, if there's no error, we return a make a response with a 204 no content status. Okay, and then we just return. And then we added just a 500 right here, in case an error would occur after trying to destroy the book. In this case, it's not going to occur, because we're not dealing with actual database, we're not doing async stuff and all that stuff. Okay, so it's just hard coded. So I just wanted you to practice thinking about different cases where you would have to return a different response, handle the errors, be it client errors or the actual server side errors, that kind of stuff. Okay, so I think we're good. And until the next lesson, bye.