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OK so now we have everything we need to do in order to add a cat in.

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Now we just need to write the code the code that looks like this.

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We're going to make a new cat and when we make a new cat We're going to pass in data.

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So I'm going to say name and let's go with George and his age.

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Let's go with an older cat 11 and temperament is grouchy.

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Just going off of my experience with cats.

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And then what we'll also do is save this to a variable.

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So we'll call it far.

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George equals new cat.

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Her name is George.

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Age 11 temperament is grouchy.

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So this doesn't actually added to the database just yet.

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There's another step which is George Dodd save.

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And once we save it will be added to the database.

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However there's a possibility that it won't save let's say that our Mangu process isn't running for

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some reason or the Internet is not working on a machine it might potentially not save.

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So rather than just saving it blindly what we can do is pass a callback function into save and this

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function will be called when the save is done.

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Whether it worked or not and it will give us two different things.

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The first is any potential error and the second is it must not call it George is the item that's returned

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to the item that was saved.

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It does call it cat.

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And what we can do is check if there's an error.

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We'll just do a concert vault log.

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Something went wrong just like that.

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Otherwise let's do a come to that log.

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We just saved a cat to the database and then we're also called Salt log the cat.

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All right.

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So there's a lot here.

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So let's walk through this one more time.

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Let's start with just the save.

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So what we're doing is trying to save George the cat to the database and repassing in this function

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that will be called once this is done.

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And this is a pattern that we're going to see all the time in mongoose.

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So we'll have things like that find and then you pass in a callback function to that and then we'll

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do the same thing for Dot remove and for Dot create in pretty much everything we do with Mongoose will

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involve a callback function and that's because this takes time.

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Javascript has to go and communicate with this process here and figure out if it went right or went

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wrong and it takes time.

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So we have to do the callback in order to have code execute after this is done.

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OK.

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So our callback takes two parameters.

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The first one is a potential error.

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And this will be empty hopefully but if not then we're going to cancel that log.

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Something went wrong.

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Otherwise we'll print out.

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We just added We just saved your cat to the database and we'll print out the cat.

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OK.

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A lot of stuff.

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So let's see how this goes.

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Let's try running this node cat stuff.

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Yes.

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OK.

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And we get we just saved the cat to the database and we got the cat that we printed out with this line

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here.

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And you can see that we have an I.D. temperaments Graci age 11.

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Name is George.

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And I just want to highlight here Kat is referring to what came back from the database because we also

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have George and we could also conc about LUGG George if we wanted to and we would see that it's slightly

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different.

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George is not what's coming from a database.

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George is what we have in javascript that we're trying to save to the database and that is what's being

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sent back from the database.

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So let me prove to you that this worked.

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We can open up our Mongo con. And then if we do show Digby's we now have cat app so we can use cat out

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.

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And then what we can do is show collections first and we have cats which was automatically created by

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pluralizing this and then let's just do a DVD cat stuff find all and we have our new cat here George

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.

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OK.

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Let's exit out and now let's create one more cat.

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So change the name of the cat from George to Mrs. Norris which is the cat from Harry Potter films his

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cat and I have no idea how old she is let's just say seven although probably much older than that.

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And her temperament will be evil although to be fair we could say that about every cat ever in the history

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of the world.

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And yes it still says George and that's fine because this doesn't actually impact anything.

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It's just the name of the variable on the javascript's side of things.

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But remember we're just writing javascript.

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But then we're saving it here.

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And it takes the data inside and sends that to Mongo and saves it in the database.

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But this has nothing to do with it.

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That's just how we refer to it instead of our code.

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OK so let's try the same thing.

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Try and save that cat again.

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Run node Julius or cat Stut Julius OK and we get we just save another catch to the database and the

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90 temperaments evil age seven name is Mrs. Norris.

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OK.

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So that's how we can add cats to the database.

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The next important feature is retrieving cats from the database and to do that we'll go back here and

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down here I'm going to show you a new method.

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And actually I'm going to comment this out otherwise every time we run this code we'll get a new cat

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in our database and that's fine.

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But I only can have one Mrs. Norris at a time.

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I don't want to have five or six of them running around in our database.

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So I'm going to come it out for now.

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So down here what we need to do is use the find method on cat which was our model we defined right here

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.

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So Cat dot find and we're just going to pass in an empty object.

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And then the callback function and this callback function is just like the other one where we take the

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error as the first parameter.

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If there is potential error and we'll check so we can start there.

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If there's an error let's to cancel that log.

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Oh no error.

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And then we'll also print out the error itself.

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Otherwise let's pass in this second parameter which is going to be the result of the dot find which

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would be hopefully multiple cats although potentially just one cat but we'll call it cats.

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Totally up to us.

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Just like this is up to us as well.

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Hopefully by now you're recognizing that anytime we have a callback it's completely up to us to decide

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what to name these parameters.

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So we'll do else cancel that log cats and let's just do that and we'll add another one in here just

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to make it easier to see all the cats.

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OK.

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And save that and let's see if this works.

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So we're going to run cat to find and repassing an empty object because we're not looking for any particular

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cats.

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We just want all of them and then repassing in the callback because remember this takes some time or

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it might not work.

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There might be an error.

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So this code is executed when this is done.

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All right.

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And I would check if there's an error you printed out.

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Otherwise you print out the cats.

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Let's now make sure you have everything else commented out except for the important stuff appear and

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we'll clear the console and then run our file.

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There we go.

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So we get our old cat conses that log and we get an array that has two different casts in it.

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Great.

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So I'm going to show you one more thing we can do to create a cat.

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Rather than doing it in two separate steps like we have here where we're making a new cat and then running

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.

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Save on that cat.

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Well we can also do.

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I'll come get this out for now.

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All of this actually is used a method create which is just like find so it's can create.

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And this is basically new and save all at once.

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So rather than making it new first and then saving it to making sure it works.

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We can just try it right away with Create which will make a new one and save it in a database.

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So let's do name.

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And I'm running out of ideas here.

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Let's just call a cat snow white.

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And age is 15 which is a number.

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And miraculously we found a cat whose temperament was nice.

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Nice is too strong a word.

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Let's just go with bland.

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There we go.

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So we save it and if we run this now it might it might not work.

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Well we'll have no way of knowing until we added the callback here.

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So again hopefully you're seeing this pattern are going to see it all the time and then we'll do our

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if ever and we'll just do this nice and quick.

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Cancel that log error.

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Else cancelled out log cat.

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And remember I call it cat because we are creating a single cat versus down here I called the cats but

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it's just a matter of what makes sense for a name.

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So in this case cats made more sense here.

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Cat makes more sense but we could also call it new cat or newly created Cat or returned cat everyone

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.

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OK so save.

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And let's see if this works.

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So now what we've done is first right here we've added this new cat that we created and we got it back

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from the database snow age 15 Blanche temperament.

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And then we also left this code we didn't commented out.

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So we also went and found all of the cats in the database and we got three different cats grouchy evil

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and bland and yes those could be their names.

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Technically that's their temperament.

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Their names are George Mrs. Norris and Snow White.

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OK.

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So we saw a lot of stuff here.

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Let's do a very quick recap and we shrink this down a bit and let's start at the beginning.

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So what does mongers Mongoose is what's known as an odium object data mapper.

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What it really means is that it's a way for us to write javascript inside of our javascript files like

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our app J.S. or express files and that javascript code will interact with our database.

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So it's basically a javascript layer on top of Mongo DB and it adds some extra fancy things in that

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we haven't really seen yet.

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But it has some some extra special methods that makes it easier on us and then we connected the cat

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app database was created for us because it didn't exist.

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But next time we connect and actually every time we've connected.

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Aside from the first time we ran the file we connected to the same cat app that already existed.

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And then we defined a schema which is a plan for what a cat looks like a name age and temperament.

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Now I didn't mention this but we don't have to have a name age and temperament.

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If we left them blank we wouldn't get any errors but we can add that functionality in and we will later

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for instance when we have a user signing up on our Web site we don't want them to be able to leave password

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blank email blank.

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We need both of them to be there.

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So there's a way to do that with Mongoose and then we have what I think is the most confusing line conceptually

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which is where we take the cat schema.

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The plan for a cat.

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And we compile it into a model which returns an object that has a bunch of methods so it knows about

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our plan name age and temperament.

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But it also adds in things like create and find and a whole lot more methods.

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So then we save it to cat with a capital C which is conventional to have it be a capital name there

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for our model and then we did things like making a new cat and then saving it.

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And the key thing is the callback or we have an error.

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And then the data coming back.

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And then we did create as well or we do cat create same exact idea.

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We have a callback and then we have another method down here find.

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So I'll be showing you a few more methods as we go.

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The point is not really that you memorized the exact syntax of the methods but just conceptually are

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clear on how this works.

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We install mongoose connect with database schema model and then we interact with the database.

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All right so that's it for now and the next video I'm going to show you how you can add mongoose to

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an express app and interact with the database inside of an express app