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Everyone are welcome back home Johnny be here with soapstar calm and in this lesson we're going to work

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on leading thoughts are.

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So we already have it where we can edit and delete comments but now we're going to take a look at the

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thoughts.

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I don't want to create one here.

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I'm going to say.

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Joining me here.

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I'm going to post it up and put in a user name here.

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And that reminds me we don't actually need that user name field anymore so let's get rid of it.

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And the reason we don't need it is because we have access to the username as part of our often user.

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OK so up here this user names are going to deleted and we are going to add a tough constraint of about

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16 here.

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You go.

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That looks good.

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And then we'll get a couple of errors here in the ADD thought the C C here should be.

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Oh well we already we already said the user id We just didn't actually remove that you didn't even feel

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like.

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So another that's gone that's taken care of.

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And we'll get back to what we were talking about which was here in the mean Visi and leading thoughts.

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All right so let's take a look at our simulator again.

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Here we have a thought and if we click here nothing happens right.

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Because here in our mean Visi up here at the top where we have the thought options tapped as we make

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sure this is working actually first from us it print more going say I thought that text I'm going to

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print or run that again and click on that.

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And sure enough it's saying it is printing out the thought text here Johnny B here.

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All right but that's not what we really wanted to do.

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Let's go ahead and cut this and move this function down a little bit further and see here and after

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that you will disappear.

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Good.

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Repaste that and get rid of this print statement as well as this comment.

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And this is where we want the alert to show if we check out our mockup.

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We just have an alert view that says delete delete comment and we can click on delete common to delete

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it.

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All right so let's say a left.

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Alert equal to UI alert controller and will initialize it give it a title of.

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See here.

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Delete the message will say do you want to delete your thought and the preferred style is action sheet.

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Thinks we need to create the alert actions when to say let delete action equal and it's spelled that

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correctly.

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Will eat you.

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And that is going to be an alert UI alert.

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Action will initialize it.

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It's a title and will say delete thought and the style is dot default and handler here are handlers

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when going to press enter and then put in action.

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And then here in the code this is where we are going to delete.

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The thought will come back to that in just a second.

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It will need a cancel action so let cancel action equal UI alert action.

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The title

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title is cancel style as docked cancel handler is no.

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So now we need to add our actions to our alerts when the same alert that an action the first one to

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be added is the delete action.

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Then we need to stay alert to add action and will add the cancel action as well and then we just need

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to present our other few controllers with the say present view controller and we want to present the

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alert.

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Animated is true and completion is.

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All right now all that is left is to actually delete our thought so we just need to get a reference

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from to say fire or dot fire store data collection and we're going to be in the thoughts ref that document.

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And thanks to our delegate function we have a reference to the thought that it was tapped on.

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So here you're going to say thought that document ID and then just say Dot delete.

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We can have a completion handler here if we want and will get the error and we'll see if that ever is

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equal to error.

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Then we will debug.

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Print and handles say could not delete thought and will print out the error description of a localized

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description.

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Else we are done and will just dismiss our alert true and no it's going to save this and run it.

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All right so we have a thought here that we created it or a little bit earlier and I'm going to put

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a couple of comments on here comment one and say yes and then comment to and add that as well.

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And then I'm also going to open up our database here.

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Let's find that common that I just added.

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Let's see here.

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OK right here.

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So you see that we have a document with a thought and then we have a subcollection to this document.

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All right.

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And you may be realizing that I'm leading up to something here.

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But when I delete this comment here delete thought.

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Sure enough it deletes.

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But check this out.

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Are subcollection of comments that belonged to that thought is still here and in fact if we refresh

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this

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you'll see here that you'll see here that this thought is now kind of grayed out and italicised meaning

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that this thought document it doesn't really exist anymore.

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It's just kind of hanging out in limbo as well and our comments collection is still here.

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So this is a characteristic of firestorm.

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Their database architecture when you delete something that doesn't automatically delete any subcollection

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or documents they're in.

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All right.

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So we need to kind of handle this on our own.

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And the way to do that.

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There isn't actually like a nice little story about collection and document dot delete subcollection

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function.

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We kind of have to write that whole function out on our own and it's a little bit longer.

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And the fire store just gives it to us so we're just going to go straight to the source.

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So if you just Google firestorm delete some collection and go right here deleting data from cloud fire

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store.

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And what we want is right here delete collections.

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And this is to delete an entire collection or subcollection in classifiers to or retrieve all the documents

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within the collection or subcollection and delete them if you have larger collections you may want to

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delete the documents in smaller batches to avoid out of memory errors.

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All right so we're just going to grab this entire function right here make sure you are in swift and

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copy it and we're going to jump back into X code and right here under our thought options tab function.

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We're just going to paste this delete function and let's kind of run through real quick.

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I should say self delete.

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All right so we got this function here that Firestar documentation gives us and the function is called

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delete and we pass into the function a collection or reference a batch size number which has a default

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of 100 and then we have a completion handler that returns an error.

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And then here inside we have some common sense here it says limit the query to avoid out of memory errors

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on large collections.

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So if you have like really big collections then you want to do this in batches and that's what this

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batch size variable is here as is when the leading a collection guaranteed to fit in memory Bashan can

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be avoided entirely.

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We're going to do that because our mix up collections are pretty small relatively.

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And so then what we do is the we get the collection and we are going to call get documents which fetches

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all of the documents in the collection.

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This limit to is something that we haven't gone over quite yet.

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But it can be used in pretty much any of the features that we've used instead.

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Right next to like the order or the wares.

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You can have dot limit too and that will limit the number of documents that you fetch to whatever you

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pass into it.

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All right and then all we do is we just do a check on the docs and make sure that we that we don't have

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any errors then we're going to make sure that they are in fact more than one documents and the subcollection

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that need to be deleted and then we're going to do what's called a batch and came batches something

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else that we haven't quite covered yet.

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But basically it's kind of like a transaction where we were able to do multiple reads and writes all

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at once but with a batch simpler documentation and all it does is just writes though.

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OK.

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So we're going to do a whole bunch of rights in a row which is going to be doing delete things and we're

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just going to throw those all in a batch and it's just going to go through and delete them all.

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And so that's what we have right here doc said that documents for each were going to batch and delete

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the document and then we call batch doc commit which actually starts the process of deleting them.

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And then we just have a couple of checks here for an error and then we then we call it.

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All right.

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So pretty pretty straightforward.

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So let's let's get to it.

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So what we're going to do is here in the thought options tapped in the delete action instead of deleting

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the comment.

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First of all we're actually going to do was run and delete the subcollection comments first and then

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we're going to delete the the thought kept.

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So we are going to say self that the elite are right to call that function that we just imported and

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the collection or reference is are just going to give it to the fire storm dumped fire stored collection.

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And this is fots ref.

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Then we're going to go to the document which is thought dot document ID.

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And then lastly to the actual collection that we want to delete which is a subcollection of the thought

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document and that is going to be comments ref OK and then our completion handler I'm going to name that

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error and in code here we are just going to do a check on the errors and see if that error actually

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we can just copy right from here from our old delete function.

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And here we're going to say could not delete sub collection.

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And then here in the completion handler instead of dismissing we're actually going to call this function

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that we already wrote which deletes the actual thought.

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OK so first we call self-taught delete to delete a collection.

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In this case is the thought subcollection.

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If it is successful then we go ahead and we delete the thought itself.

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All right.

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And let's go ahead and does this don't want to run.

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Can to create a new common to real quick.

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You comment and post it.

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And we got ourselves a crash.

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So what's happening here is that the this is still looking for that username textfield that I deleted.

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And I think I was confused earlier when I was looking at the View Controller and I thought that we had

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already taken care of the username part right here.

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So instead of looking at this user name we want to look at is the display name value of our currently

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off in user and that is here in the off dot dot.

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Current User dot display name.

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And that's an optional string.

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So I'm just going to provide a no coalescing value of an empty string and then we're going to get rid

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of this trick.

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This guard statement here and we're also going to get rid of this outlet here and I'm going to build

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that and make sure that that software can build succeeded.

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So it's going run this again.

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All right.

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So I'm going to create a new post make sure that's working.

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New post and post.

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And sure enough here we go.

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I just want to add a couple of comments here comment.

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One added comment to add it and then I'm going to check out our database here and let's see here that

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one that we just added And see here.

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All right so here we are this is the new thought and we have a couple of comments.

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So now let's see what happens when we delete that.

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All right.

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So we're going to pull this over here and I'm going to delete delete the thought.

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And we should see these disappear first and then that actual thought document disappear as well.

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All right so if we refresh this then that thought nor those that subcollection will be anywhere to be

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seen.

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But this one if you want to get rid of it all you got to do is select the document and say delete document

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and that will delete all of the nested data.

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So deleting it from here on the dashboard that will delete the document and it subcollection is just

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just an F why.

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All right so it looks pretty good.

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Looks like that's working.

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All right.

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Great.

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So now we are able to edit and delete comments and now we're also able to delete comments or thoughts

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which actually we now know how to go and delete collections and subcollection as well.

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But there is a little hitch here that I want to go over in the next video so I hope you're ready for

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that and I'll see you in the next one.