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In this video, let's implement document updating. | www.downloadly.ir
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And so, here, in our update tour handler, let's start by
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making it an async function.
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Then, or try catch block, and so I'm doing this
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very quickly now, because we're already used to this
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at this point.
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Right?
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So this goes into the try block and then
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I simply get this one, here, from the catch block
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of this other function.
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All right, so.
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Here we go.
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And so now, what we need to do here
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at the beginning of this try block
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is to basically query for the document that
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we want to update and then update it, all right?
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And we can actually do that
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all in one command with mongoose.
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And, remember, again, that we're gonna update the tour
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based on an ID, okay?
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So, it's a similar situation like this one here,
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where we find by ID.
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And now, we can actually do something very similar,
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which is find by ID and update.
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So again, everything in one query.
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So, let's do tour.findByID
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and update.
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Okay, so, what do we need to pass in here?
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Well, of course, the ID, so that we can first find
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the document that is to be updated.
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So, just like before, that is req.params.ID,
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and then the data that we actually want to change.
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And that data will be in the body,
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just like in the post request.
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So req.body, okay?
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And then, actually as a third argument,
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we can also patch in some options, and we will do that.
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And the first option that I want to specify is new
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and set it to true.
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Because this way, then the new updated document
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is the one that will be returned.
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And since we want to send back that updated document
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to the client, we always want this method
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to actually return that new document, okay?
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So this way, it actually then makes sense to
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await this query and then save it to a new variable.
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So then simply call it tour here,
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and then again, await the result of this query.
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So all of these methods that we've been using on the tour
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so far, so find by ID and update, or,
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well, not really create, but find by ID or find,
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all of these will return queries, so they are query methods
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and let me actually show that to you
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in the mongoose documentation.
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So, up until this point, we didn't have a look at
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the documentation so far.
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And so, let's quickly do that.
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So, on the model, which in our case is tour,
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we have all these query methods, right?
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So you see find, you see find one, you see find by ID,
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which is just a shorthand for find one.
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Then you see find by ID and update,
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which is the one that we're currently using,
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and which, in fact, is just a shorthand for
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find one and update, where we're querying for an ID,
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so similar to what we had in the last lecture, okay?
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And actually we can click on any one of these,
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so let's do the one that we're using currently,
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and that will then really take us to the API documentation
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which shows us how to really use a certain method.
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So you see that we passed the ID, so the value,
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off the ID to query by, we passed the object with
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the data to be updated, and we passed an options object.
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And down here we can actually see
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the options that we can set, so remember,
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we just set new to true, and so as it says here
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that will then return the modified document
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rather than the original.
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Now, another one that we actually want to set to true
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is this run validators, so that each time that we update
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a certain document, then the validators that we specified
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in the schema will run again, okay?
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And we will talk a lot about validators and validation
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a bit later in the section,
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but I'm gonna leave it here for now so that we, basically,
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don't forget it.
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Okay?
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Give it a save now, and actually I wanna go back here
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just to show you how many methods
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we actually have in mongoose.
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So, on the model, we have all of these methods here
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that you see in this list.
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So for example we used create before,
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we also used find.
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Okay?
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And so the ones that you see here in the top,
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they are available right on the model,
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and that, in our case, is the tour.
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Now, down here you, for example also see
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model.prototype.safe for example.
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And this one, we actually also already used
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right when we first started to work with mongoose.
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So I'm not sure if you are familiar with this,
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but in java script model.prototype always means
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an object created from a class, or in this case,
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created from a model.
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And so, the save method here, refers to a save method
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called on a document and not on a tour.
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And remember that that's exactly what we did.
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And I think I still have it here as a comment.
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Yeah, right here.
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So, we had a tour, this new tour variable here
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which was created from the tour model,
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and so this new tour here got access to the save method
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because that is part of the prototype object of this class.
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All right, now I don't want to bore you with the
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fundamentals of java script, but it is important
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in order to understand the documentation, okay?
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Because at some point you will need to use documentation,
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because mongoose is yute.
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And I will actually teach you a lot of the stuff
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that's important in there through all of this course,
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but sometimes you will still need something that
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I didn't show you in this course.
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And so it's important that you really understand
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the documentation as well, okay?
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And so, again, when you see model.prototype here,
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you know that the save method here
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is going to be available on all of the instances
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created through a model, okay?
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And so, not the model itself.
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So, for example, if you tried tour.save
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you wouldn't be able to use it.
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It would give you an error, but instead, if you tried save
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on a document created through the tour,
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then it would, of course, work, okay?
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I hope that makes sense.
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And, anyway, you see that we have a lot of other stuff,
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so we have to query, which we already talked about,
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because, for example, find by ID and update, or find,
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or find by ID, all of these will return query objects.
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And so, later on, when we're gonna implement stuff like
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sorting or filtering we will then use this query object.
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Okay?
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So, let's go back, we kind of got off the track here
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by looking at the documentation,
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but, again, I think it's really important
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to start looking at the documentation,
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because a course like this can only take you so far,
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and I hope you already know that at this point, okay?
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It's really important that you're also able to
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find information on your own, and I wanna show you how
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to do that also in this course.
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Anyways, let's now actually also send
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this newly updated tour back to the client,
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which, right now, we're not doing, because we have
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simply this updated tour here string.
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So let's get rid of that and simply send to tour.
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And remember that this, in fact, is actually this.
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So, the tour property is set to the tour object,
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but, thanks to ES6, we no longer have to do that
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when the property name has the same name of the value.
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Okay, so let's get rid of that.
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That makes our code look a bit better.
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Okay, and let's now test it.
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Back to postman, here we have the updated tour route.
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And so, let's actually do it
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on this same ID that we used before.
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So, this one.
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Then we come to the body, here, and let's change--
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Well, what are we gonna change here?
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Well, let's change the price to, like, 500.
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So, price, 500,
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send it, and indeed this gives us
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the newly updated object with the price
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already set to 500.
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And if we now get all tours, then that, of course,
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should be reflected here.
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And here it is.
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But now, let's say that we set it to a string.
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Let's take a look at what happens, then.
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Well, then we actually get an error.
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And that's because we ran the validators again.
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So, remember that we have--
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Where is that?
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Oh yeah, here.
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So here we specify that the validators should be run again.
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And so, right now the price is no longer a number
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as it is expected, right?
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So in a schema we say that the price should be a number,
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but, of course, java script, or mongoose, actually,
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cannot, basically, convert this string here to a number.
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But that is what we expect.
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So here it says kind should be number.
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And so, therefor, it gives us an error,
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simply because we're running the validators again.
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So, let's put it back to 500 and then, of course,
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it's gonna be back.
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All right, now, keep in mind that we're actually
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doing a patch request here.
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Now, if we were doing a put request, remember,
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then you would expect that the original object
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would be completely replaced
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with the new one that is sent in, okay?
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So, in that case it would no longer work
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the way we implemented here
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because this one simply really updated the fields
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that are different here in the body, okay?
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But anyways, I think that the patch method
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is actually way more useful, and so,
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that's gonna be the only one that implementing here.
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Cool, so we have three of our four correct operations
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implemented, only one more left to go,
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which is gonna be delete. | www.downloadly.ir
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