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It's time to move on to that final crud operation which is D for delete now like with create read and

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update we'll be able to delete individual documents or we can batch delete multiple at the same time

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the two methods we're gonna use to get this done are under D for delete in the API docs we have delete

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many for deleting multiple and delete one for just removing an individual one.

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Now in the past the method you used to remove data was actually called remove which is down below.

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That's been deprecated and delete many and delete one are now the future of deleting data with Mongo

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D.B..

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So we're gonna go ahead and kick things off with delete one.

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Now the API for both is very similar.

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We provide the filter to target the document or documents.

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We want to remove.

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Then we have the options which we're not going to provide as they're not needed.

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And we have the callback which we're also not going to provide since we'll use a promise instead.

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So for delete 1 and delete many all we really have to do is provide these search criteria similar to

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what we did with find and find one.

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Let's go ahead and move into Mongo D.B..

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J asked to mess around with this.

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I'm going to remove our calls to update many and Update 1 and we will start by using delete many to

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delete multiple documents from that user's collection.

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What I'm going to do is remove all of the users who have the age of twenty seven.

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So right here if I refresh things there are two.

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I have Andrew and I have Gunther both with twenty seven as the age.

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My goal is to delete all of those with one single operation.

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So for Mongo D.B. J S will start off like we've done plenty of times before.

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D.B. dot collection we're looking for the user's collection and we will be using delete many to delete

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multiple documents and once again the only argument we're going to provide is the first one where we

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provide our search criteria.

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In this case we are looking to delete documents where the age is twenty seven.

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Now if I wanted to target two things I could add multiple properties onto here like for example deleting

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people whose name is Andrew and age is twenty seven.

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In this case we just want to delete based off of this one field.

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Now from here we can go ahead and set up our call to then.

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So right here we'll get access to the result.

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If we were able to perform the operation and we can also set up our call to catch and here we'll get

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access to the error.

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If we were not able to perform the operation and once again we'll just log both to the screen console

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dialogue printing result and then down below console dialog printing the error.

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Now with this in place we're actually all done.

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There's not a whole lot to deleting data and we can go ahead and run the script.

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What I'm gonna do is shut it down and using control C and then I'll start it up once again using up

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and enter.

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That's going to rerun things and we can see that on the result.

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We have a whole bunch of different pieces of information but I also have deleted account which is showing

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too.

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So this is the main result we get back allowing us to confirm the number of documents that were removed.

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Right here I can go ahead and refresh the user's collection and I can see that both of those are now

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gone.

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So there's no longer anyone with the age of 27 in the database.

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They've all been deleted.

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So with this in place we know how to use the delete many function to delete multiple documents.

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Now we're going to move on to the challenge for the video where it's up to you to use delete one to

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delete an individual document.

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Right here I have the challenge comments for this one.

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Your goal is to use delete one to remove a single task.

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First up you're gonna ground the description for the task you want to remove.

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So over inside of robo 3 T you could remove any of your tasks by their description.

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So I have these three right here as options for me.

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Now once you've picked the description go ahead and copy that to the clipboard and set up your call

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down below so you can refer to the documentation for delete one to figure out how it's supposed to be

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used.

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Hint It's basically the same as delete many.

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Now once you found that Colin place you are going to not provide the callback and instead opt for the

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promise.

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So toss on the then and catch method calls to set up your handlers and finally test your work rerun

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the script and make sure the one task you targeted is gone and that the others are still in place before

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I set you free.

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I will comment out our other call up above and down below.

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Right here you can add the challenge code.

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All right.

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Pause the video.

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Knock that out when you're done come back and click play

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out that go.

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Let's go ahead and kick things off by grabbing the description for the document.

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I'm gonna go ahead and remove clean the house.

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Now it's already done.

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So I don't need to keep it around right here.

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I'll grab its description.

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Next up I'm going to bring that over to my code and I'm going to call the correct method.

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That's going to be D.B. dot collection.

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I'm targeting that tasks collection and I will use delete one to delete just an individual item right

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here.

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I provide my query I am looking for the task where description equals a specific value.

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The string I just copied it to the clipboard.

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Perfect.

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Now from here we can go ahead and move on to the next step which is to add our promise method calls.

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Now there are so many ways we can structure code when we have a lot of chaining going on like this.

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I could take delete one and move that down to the next line.

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That would be a valid way to get the job done.

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Or I could go ahead and do something similar to what we've been doing before and simply break up the

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argument like this.

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And then toss on then setting up my callback right here.

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I'll get the result and I'll go ahead and dump that to the console and then down below that we'll make

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sure we use catch to handle those potential errors right here.

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I can call that E for short.

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Or we could just listed out in its entirety error.

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And once again I'll just log that.

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All right.

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All done.

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Let's go ahead and test things out.

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I'm gonna remove the challenge comments.

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I'm going to save the file and before I rerun it I'll just refresh the data to make sure clean the house

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is still showing up and it is from the terminal.

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I'll shut down the previous script.

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Start it up one more time.

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Right here I can see I have a delete count of one and if I refresh the tasks collection I can see that

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first document is gone.

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So there we have it.

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We now know how to create data read data update data and delete data.

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Now the goal of this section wasn't to start building out our next app which is that task manager REST

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API.

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The goal here was to just get comfortable working with Mongo D.B. and promises so we can use these together

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with Express to build out a more complete and real world application trying to learn about Mongo D.B.

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while also integrating it into an application would would've made it for quite a difficult journey.

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That's it for this video and that's it for this section.

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I'll see you in the section introduction for the next one which is coming up now.