265. Using a Service for Http Requests

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The code we have thus far is not bad and it does its job.

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And if our application were as simple as it is here,

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it would be perfectly fine.

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But in bigger applications,

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and maybe even in this one,

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we already have a quite big component with a

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lot of code that is only indirectly related to the user interface.

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Of course, we wanna send a request when a button is clicked and we wanna display that response

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data.

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But for example,

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transforming the result,

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transforming the data,

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we can do it here.

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It's not inherently bad,

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but it is a nice practice to outsource that into services.

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So that services are the parts in your Angular application that

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do the

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heavy lifting,

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the dirty work,

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and your components are relatively lean,

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as lean as they can be,

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and are mostly concerned with template -related work.

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So with things like the isFetching property and so on.

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And therefore,

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let's create a new service now,

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the posts service here.

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And I'll create it by exporting a class,

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posts,

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service,

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and we need to provide that.

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And for that,

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we can use two approaches.

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We can use at injectable,

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which you need to import from at AngularCore.

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And there we can pass an object and set provided into root,

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which is the more modern and recommended approach.

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But you could also provide it here in the providers array of the app module.

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And this also wouldn't be bad or a problem.

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Here,

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however, I will use this approach.

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Now, what's my idea behind that service?

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In this service,

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I wanna have my HTTP request methods.

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So the methods that do the HTTP requests,

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and I only want to get the responses or the

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message, whether we're done with the request in my front end.

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So therefore in this service,

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I will add a new method.

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create and store a post.

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You can of course name this however you want.

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And there I expect to get a title,

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which is a string and the content,

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which is a string as an argument,

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let's say.

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And here I want to send my HTTP request.

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Now,

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of course, I also want to be able to fetch my posts.

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So we'll add fetch posts here.

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And there I also want to send a request.

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Now, of course,

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I only want to move my code over.

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That's in the end what I want to do here.

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So let's grab that HTTP request here from onCreatePost and

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let's move it into the post service here.

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Now we're sending the HTTP request here.

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However, for this to work,

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we need to inject the HTTP service into this post service.

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So let's add a constructor.

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And with the help of that constructor,

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we inject the HTTP client.

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and we store it in a property named http and the http client

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is imported from at angular slash common slash http

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now of course here we have no post data property

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anymore i can create that here though and this will in the

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end be of type post and therefore it will have

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a thailand's on but we first of all need to import our own post

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model so let's import post from dot slash post

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And now to be a real post,

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we need to set a title property here,

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which is equal to our title we're getting as an argument.

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And we need to set a content property,

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which is equal to the content we're getting as an argument.

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So the right side of the colon refers to these arguments here.

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Now that's the post data we're sending.

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And now we can call create and store a post to

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send that request.

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So back in the app component,

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I now need to inject my own posts service,

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private posts service,

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like this,

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and make sure to add that import path here at the top.

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You need to import posts service from there.

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And now in onCreatePost,

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I simply call this posts service,

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create and store post.

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I get an error here because I need to pass some data to that method.

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I need to pass the title and the content.

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Now I get my post data here.

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So I access postdata .title and my second argument I send

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is postdata .content.

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And with that,

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we should be able to create new posts.

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Let's add a new

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post here, the best Angular course,

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which this one hopefully is.

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I'm of course interested in your feedback.

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So I hope so.

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Send that post.

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S… Speaker 1 (265. Using a Service for Http Requests)

Now we have no logic to automatically update our list of posts down there,

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but that's fine.

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We can click fetch posts again,

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and now we see our post here.

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So that now still works,

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but now the logic was outsourced into the posts service.

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Let's do the same for fetching posts.

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Let's grab this logic here and we'll

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have a problem with is fetching,

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but I'll come back to this.

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Let's grab this logic here and move it into fetch posts

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in the posts service like that.

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Now let's remove is fetching and let's remove this loaded posts

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because we don't have these properties here and we don't really need them

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here in the post service.

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Is fetching and the loaded posts clearly belong into our

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app component and not into the service because the component is where we use them,

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where we want to display them or where we need them to change what we display

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in the template.

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Let's focus on the rest of this code for now.

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We're missing the map operator,

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so let's make sure we import that here.

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Let's import map from rx .js slash operators.

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And with that,

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we have a request that should work,

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but we'll still need to fine tune this later.

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At the moment,

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we can get rid of that private method here,

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of course, and instead where we previously called this fetchPosts,

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we can now use the posts service and call fetchPosts there.

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So we do that here in onFetchPosts and in ngOnInit.

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However, what you will see of course is that now we have no posts

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available because whilst we're running that code in

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the service and indeed you can see that if I click fetch posts,

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a HTTP request is sent and we are fetching the posts.

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Whilst all of that is happening,

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we're not seeing the posts here because we lost the connection between

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the data we fetched in the service and our template.

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Let's fix that.

265. Using a Service for Http Requests

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