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‫Welcome back.

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‫So after some heavier theory lectures,

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‫now, we're finally gonna start implementing our data model

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‫and starting with the locations.

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‫So in this video, you're gonna learn all about

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‫geospatial data in MongoDB.

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‫And this is really a topic

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‫that I personally find really exciting.

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‫Now, remember from the previous lecture

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‫that our location data will actually be embedded

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‫into the tours.

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‫And so therefore, we're basically gonna declare

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‫everything that is related to locations

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‫in our tour model.

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‫All right, so let's open that one up and right at the end,

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‫let's start by adding the startLocation.

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‫Okay, so we will have startLocation

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‫and then also, locations in general.

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‫Now, MongoDB supports geospatial data out of the box.

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‫And geospatial data is basically data that describes

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‫places on earth using longitude and latitude coordinates.

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‫Okay, so we can describe simple points

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‫or we can also describe more complex geometries

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‫like lines or even polygons or even multi-polygons.

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‫So really, everything is possible

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‫with geospatial data in MongoDB.

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‫Okay, so let's add our startLocation field here

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‫and then let's actually implement this geospatial data.

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‫And MongoDB uses a special data format called GeoJSON.

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‫All right, so.

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‫GeoJSON, in order to specify geospatial data.

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‫And now, how does this actually work?

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‫Well, this object that we specified here

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‫is actually, this time, not for the schema type options

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‫as we have it, for example, up here.

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‫So this object here is for the schema type options.

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‫Remember that?

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‫But now, this object here is actually really

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‫an embedded object.

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‫And so inside this object,

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‫we can specify a couple of properties.

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‫All right, and in order for this object to be recognized

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‫as geospatial JSON, we need the type

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‫and the coordinates properties, all right.

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‫So we need type and we need

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‫coordinates, all right.

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‫And so now, each of these fields here,

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‫so basically, each of these sub-fields is then gonna get

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‫its own schema type options.

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‫All right, so basically here, it's a bit nested,

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‫so we have one level deeper.

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‫Okay, so we have the type schema type options

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‫and then we also need schema type options for coordinates

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‫and again, just like we have up here in these other fields

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‫with the difference that these are now sub-fields.

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‫So type needs the type of string,

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‫all right,

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‫and the default should be point.

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‫So remember how I said that we can specify

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‫multiple geometries in MongoDB?

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‫And the default one is always point.

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‫But again, we could also specify polygons or lines

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‫or other geometries like that.

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‫But in this case, for the startLocation,

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‫it really should be point.

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‫And so let's actually make that the only possible option

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‫by specifying the enum,

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‫so the enumeration property.

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‫So remember, we can specify an array

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‫of all the possible options that this field can take

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‫and so in this case, we only want it to be point, all right.

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‫So we did that somewhere up here.

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‫Yeah, right here with the difficulty

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‫where we said it can only be either medium or difficult.

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‫Right, and so here, we're doing the same thing,

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‫but only with one option, okay.

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‫So we need to define the type, remember,

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‫and also, an array of coordinates.

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‫Okay, and so we do that by saying number,

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‫but then in these curly brackets.

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‫Okay, and so that basically means that we expect

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‫an array of numbers

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‫and this array, as the name says, is the coordinates

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‫of the point with the longitude first

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‫and only second, the latitude.

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‫And so that's a bit counterintuitive

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‫because usually it works the other way around.

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‫But in GeoJSON, that's just how it works.

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‫So if you were to go, for example, to Google Maps

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‫in order to get your coordinates,

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‫then you will see first the latitude and then the longitude.

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‫Let's actually take a look at that.

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‫So

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‫open up Maps here.

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‫Let's say New York.

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‫Okay, and if we now click somewhere here,

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‫say here, then we get the coordinates

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‫first with the latitude and second, the longitude.

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‫All right, and in case your not familiar with that,

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‫let's just zoom out a little bit here,

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‫so we can see the entire earth.

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‫Wow, what's that?

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‫Okay.

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‫So the latitude is basically the horizontal position

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‫measured in degrees starting from the equator,

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‫so from here to up here.

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‫So in the equator, it's zero degrees

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‫and up here, in the North Pole, it's 90 degrees.

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‫And then the longitude

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‫is just the same thing, but vertically.

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‫So it's the position starting from a meridian,

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‫which passes somewhere here, okay.

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‫And so the longitude is the vertical position

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‫starting from here.

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‫And so that's why this point here that we got,

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‫somewhere here,

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‫somewhere here in Manhattan, has a latitude of 40

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‫and a longitude of -73.

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‫All right.

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‫But anyway, let's go back to our code here, of course,

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‫because I also want to specify a property for the address.

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‫So add another string and then also, a description

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‫of this startLocation

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‫and that again, as a string, all right.

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‫And we're not gonna say that any of these fields

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‫should be required because we want to be allowed

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‫to leave the startLocation blank.

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‫Okay, so again, in order to specify geospatial data

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‫with MongoDB, we basically need to create a new object

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‫such as we did here.

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‫And that object then needs to have at least two field names.

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‫So coordinates has this array of numbers

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‫and then the type, which should be of type string

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‫and should be either point or some other

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‫of these other geometries that I just told you about before.

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‫Okay, and we can then of course add some more fields

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‫to this object such as we did here, all right.

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‫Now, remember how in the last lecture we said

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‫how we were gonna embed all the locations

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‫into the tour documents?

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‫But right now, the startLocation here is not really

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‫a document itself.

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‫It's really just an object

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‫describing a certain point on earth.

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‫But in order to really create new documents

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‫and then embed them into another document,

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‫we actually need to create an array, all right.

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‫So it's actually very similar to what we already have here,

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‫but it needs to be an array.

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‫And so that's what we're gonna do with our locations.

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‫So locations, and now, I'm creating an array.

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‫And then in this array is where I'm gonna specify

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‫the object such as I did it before in startLocation.

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‫Okay, and you will see what this will look like

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‫in a second in the Compass application.

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‫Okay, and so now, it's actually quite the same as before.

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‫So the type, remember, for geospatial data

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‫needs to be string.

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‫The default needs to be point.

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‫And also, it cannot be anything but point, okay.

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‫So point.

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‫Again, we need the coordinates as an array of numbers

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‫and also, for all of these other locations,

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‫we still want to specify an address and a description.

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‫So string and here, I also want to specify the date,

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‫so as a number.

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‫And this date will basically be the day of the tour

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‫in which people will go to this location.

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‫Now, if we wanted to make it simpler,

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‫we could delete the startLocation all together

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‫and then simply define the first location

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‫as the startLocation and set it to day number zero.

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‫All right, but I decided it's nice to also have

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‫the startLocation as a separate field.

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‫Okay, so this is how you create embedded documents.

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‫Remember we always need to use this array, okay.

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‫And so by specifying basically an array of objects,

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‫this will then create brand new documents

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‫inside of the parent document,

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‫which is, in this case, the tour.

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‫All right, now, in order to create some locations,

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‫I'm actually going to import all our original data.

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‫All right, so instead of creating new tours,

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‫I will delete the ones we have

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‫and then import the complete data.

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‫So here, in dev-data,

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‫remember that before we imported tours-simple.

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‫Okay, so this kind of data here.

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‫But we also have tours and this then actually has

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‫the locations and the startLocation.

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‫So I'm not sure where that startLocation is.

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‫Ah, here it is.

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‫So this is how we specify the startLocation

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‫and you see that we have type set to point.

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‫We have our array of coordinates.

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‫And then of course, we have description and address.

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‫And then down here, in the location, we have an array,

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‫which then contains one object for each location.

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‫And you see that actually each of them gets their own id.

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‫And so these really are documents

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‫and not just simple objects.

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‫All right, so let's go here to our import-dev-data

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‫and replace this here just with tours.

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‫Give it a save and then remember, we need first to delete

205
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‫and then to import.

206
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‫So going to another console here.

207
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‫We now want to run node,

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‫dev-data and then import,

209
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‫so actually, in the data folder, and then import.

210
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‫And start by deleting and let's wait for it and indeed,

211
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‫and now, import.

212
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‫And here we go.

213
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‫And let's check out Compass now.

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‫Come to our tours.

215
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‫And so indeed, you now see the startLocation here

216
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‫as an object.

217
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‫Okay, and when you open that up,

218
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‫you see all the data that I just showed you before

219
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‫in the JSON file.

220
00:11:12,390 --> 00:11:15,140
‫Right, then here, also, the locations,

221
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‫which you see as an array, so type array.

222
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‫And then in there, we have all of these objects

223
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‫and each object then also has its object id.

224
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‫Okay, and so again, this is proof that we have now created,

225
00:11:28,680 --> 00:11:31,450
‫embedded, or de-normalized datasets,

226
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‫so datasets that have a really close relationship

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‫with the tours data.

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‫And so that's why we chose to really make it part

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‫of the tours instead of creating its own collection

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‫just for locations, right.

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‫So we will actually use this a bit later in this section

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‫once we start to create some special geospatial queries.

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‫Okay, and with geospatial queries,

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‫we can do really amazing stuff

235
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‫like finding locations data closest to certain points

236
00:12:00,570 --> 00:12:03,220
‫or find all locations inside a certain radius

237
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‫or a certain sphere.

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‫And really, the possibilities are absolutely endless, okay.

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‫So we will just see some applications of this

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00:12:11,760 --> 00:12:13,670
‫by the end of this section

241
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‫because for now, I really just wanted to show you

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00:12:16,090 --> 00:12:20,183
‫how we can create embedded datasets just as we just did.