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In the last section we put together a simple query to look through our survey collection and find all

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the surveys that were created by the current user.

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However we realized that if we stick with this query right here we'll also get the recipient list associated

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with every single survey record and that might have several tens hundreds thousands of email addresses

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associated with each one.

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And clearly our dashboard component inside of our application doesn't really care about that big list

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of emails.

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So I think that we can probably figure out some way to tell mongoose that when we go out to find this

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list of surveys do not return the recipient list and the response.

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OK.

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So we're going to look at the mongoose documentation to figure out exactly how to do this rather than

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have me just tell you how to do it.

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So I want you to get somewhat familiar with Mangus documentation.

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So going to change on over to my browser and in a new tab we're going to search for mongoose.

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J.S. Okay.

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So here's longers OTM.

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This is what we really want right here.

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So a click that here's the mongoose home page.

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We want to read the documentation.

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And then this pops us over to the documentation for mongoose.

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Now one quick note I want to throw out to you the documentation for Mongoose is really split into kind

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of like two separate locations.

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First on the left him Nav. over here you'll see this section called guide and underneath guide there

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is a lot of documentation about very particular subjects and each of these are written like little articles

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that you can check out and learn more about particular items.

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So if I click on validation it will give me some plain English definitions about how validation works

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with mongoose.

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I can also get a better idea of how say queries work right here.

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However if you want the real raw documentation that tells you about all the different particular methods

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and functions that you can make use of then you want to scroll down to the very bottom of the left 10

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Nav. over here and find the section called API docs so this is the kind of second location where all

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the documentation is concentrated.

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You've got that list of guides and then you've got this single one large API doc and I do mean large.

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For example if I start to scroll down you'll see the scroll bar over here yeah.

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It's a lot of stuff all on one page and kind of the bad side to that is it makes searching for documentation

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side if you're kind of challenging.

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There are some quick links down here on the left now that we can click on now that will tell you more

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about very specific areas inside of the mongoose library.

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But this kind of assumes you already know what you're looking for.

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And so for us in this particular case you know we don't really know what we're looking for.

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So it might be tough for us to find exactly the documentation that we want to look for.

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And so again remember that we just spoke about some tips and tricks around mongoose.

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Remember just about everything you could ever want to do around mongoose has a stack overflow question

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around it.

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So you can always do a nice quick search and say hey how do I do X Y Z with Mongoose and then hopefully

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that might give you some keywords to search for in the documentation.

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Now in this case I of course already done some research for us at a time and so I'm going to kind of

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point us in the right direction to find the documentation that we want to reference in order to figure

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out how we can tell mongooses not to return that list of recipients.

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So on this API doc page I'm going to hit command F or control f to bring up the search interface.

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Now we're going to do a search for pounde select and then you'll notice that there's six results here.

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So I'm going to keep searching until I find queery pound select right here OK.

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So if you've read the documentation says very simply which document fields to include or exclude and

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then very importantly you'll also see this kind of exclusion or inclusion of different fields on a record

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referred to as projection.

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You'll see that term sometimes in the mongoose or Mongo divi documentation.

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So the terms you know essentially this idea of including or excluding fields or white listing or blacklisting

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fields or creating a query projection they're all talking about the same thing.

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They're all saying when you go into the database and look for some data and pull it out.

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This is a set of fields that we want to have be returned.

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So essentially we're working with projections here so here is the documentation around how to do this.

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And the way to read this head right here.

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This says on the query class and then that pound right there indicates a high instance.

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So there is an instance method called select.

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So back inside of our application when we call survey done find right here.

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This returns a query object from Mungo's.

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And so after we do this initial query right here we can then train on as many additional aspects to

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the queries we want.

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So for example at the very end of this line or remove the semi-colon and then I can do a newline tab

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in and say Dot select like so and then I can start to customize the query that was created on this first

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line right here.

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Now just a quick note.

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We don't actually have to put this on a new line or indent it.

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It could just as easily go on the line right above it like so but usually just to make these queries

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a little bit more legible.

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Will New Line it and indent it so it reads a little bit more like plain English as OK go through alerts

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surveys find based on this criteria and then select these given properties inside of here.

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OK so that's kind of how we read this thing right here in how we make use of the Select function to

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pull off only specific properties.

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So let's scroll down a little bit more and get a better example of how to use this thing.

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OK.

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So basically on the query object or whatever query we create we then say does select and if we want

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to exclude specific fields we can pass in a string of dash and then the property name.

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Now here's something really interesting about mongoose that personally I find really really irritating.

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You'll notice that they give you one example right here of Oh yeah you can use a string to specify the

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property names you do or don't want but then they also give you this alternate syntax down here where

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they say oh but also you could just pass an object that specifies the properties that you want or the

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properties you don't want with either 1 or 0.

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And so to me it's kind of like you know why not just have one way or the other like either give us the

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string method or give us the object method.

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Otherwise it kind of just makes life a little bit unclear.

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And you know if you're an engineer and you've only ever learned the string method for including fields

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if you then see some code that uses an object you'll probably be sitting there saying like OK what's

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going on here.

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But you really know what's going on already is just this slightly different syntax that does the exact

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same thing.

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Anyways just one of my kind of pet peeves I guess I scroll in here or zoom in for one second because

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I want to point something out in particular.

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OK that's too much too much.

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Sorry.

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Let's go back to select.

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OK so here's what we are just looking at.

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So we're going to be going with this object syntax right here because I think it's just a little bit

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more obvious what's going on.

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But one thing I want to tell you is that the documentation says OK pass an object where the keys are

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the properties that you want to either specify to include or not include.

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And that shows a value of either 1 or 0 1 meaning include this property in the response or whatever

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gets pulled out of the database and a zero meaning don't include this property.

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So another kind of weird thing around the documentation here.

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These ones and zeroes are really just a shorthand representation of true or false.

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So you can either say a is one but you could just as easily say in like in the code we write you could

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say a is true.

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And I think using a true is way more clear what's going on there than saying select a of one like what

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does one mean.

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Right.

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I mean it's another item where if another engineer comes on the scene they're going to say select a

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of one why are we only finding results in this query where the property a is equal to one like that

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doesn't make any sense.

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So again another weird thing around the documentation here anyways.

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Hey that's enough complaining to me let's just do a select statement.

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OK.

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So back over inside of our code editor we're going to find the select clause on here.

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We're going to pass an object and then we're going to say specifically do not give us the list of recipients

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so we'll say recipients false.

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So do not include the recipient's property when we pull the list of surveys out of our database.

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OK.

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And I'll make sure that after the select statement I'll put on a semi colon and remember that on the

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line before it we should not have a semi-colon and it looks like pretty or wants to put everything on

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one line anyways whatever.

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OK.

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So I think that's about it for our API.

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Slash surveys end points we are making sure that the user is logged in.

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We specify that we're going to write some asynchronous code.

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We reach our database find all the surveys created by the current user.

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And then we specify that we do not want the result set to include the recipient's field.

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So I think that this is looking pretty good.

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Let's now continue in the next section where we will test out this point and we'll also get started

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on the front end aspect of this feature.

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So I'll see you in just a minute.