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Now our post model is taking shape

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and it's able to save a new post,

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update an existing post, and delete a post.

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There are two functionalities that are missing,

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which we absolutely also need to add.

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And that's the functionality to fetch a list of posts

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and the functionality to get a single post in the end.

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Now let's start with fetching a list of posts.

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What we can do for that is we can add another method.

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But now, the trick is

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that we will actually not instantiate this post-class

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before we wanna call this method.

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Because whilst it made sense to call save and delete

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on an instantiated post, so on our concrete post object,

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if we're about to fetch a list of post objects,

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we have no single post object yet.

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And to make this work,

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JavaScript classes have another feature

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which is called static methods.

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You can add a method, like fetchAll, for example,

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and add the static keyword in front of that.

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The special thing about static methods is

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that you don't call them on the instantiated object,

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so on the object that's based on the class,

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but instead on the class itself.

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And we can also turn this into an async method like this.

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So back in blog.js, where I now do need all my posts,

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which would be for the admin page here.

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There, I'm fetching all my posts.

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We can now copy this line of code here,

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go back to post.js, and add it in there.

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And then, here we can just return all those posts like that.

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Now back in blog.js, again,

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this means that we can get all the posts by calling Post,

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so using the class which we created,

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and which we are importing under that name

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in this blog.js file, .fetchAll.

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And that's the difference to save and delete.

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We called save and delete on existing posts objects,

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like here in line 116, in my case.

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We first created the post and then called save

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on that created post.

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Now, we're not doing that.

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Instead, we're calling fetchAll directly

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on the class itself.

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So I can await this here,

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and then I will still have my posts.

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But the logic for fetching to posts now resides

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in a different place.

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It now resides inside of our model

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with the help of such a static method.

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And that's why static methods,

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a new feature which we haven't learned about before,

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can also be very helpful if you wanna use a class,

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not just as a blueprint,

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but also for grouping related functionalities together.

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Because that's what we're doing here in the end.

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We're grouping all the posts-related functionalities

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together into one class.

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And with the help of static methods,

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we can also include functionalities that don't act

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on a single post that already exists,

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but that are instead only generally related to posts

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and working with posts.

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Now, just as I have the static fetchAll method

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for fetching all posts,

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we can, therefore, also add another static method

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for fetching a single post by its ID.

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Though here, for a single post, we could, of course,

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argue that we instead create a fetch function,

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a fetch method like this, which is not static,

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where just as with deleting,

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we check if we have an ID, and if we don't, we just return.

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Because we need that ID to then populate this post object,

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which we created with the data that was fetched

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from the database.

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So that means that in blog.js,

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where I am fetching the data for a single post,

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here in this get route,

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I am copying, or cutting, this logic,

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and I will execute this here in my post model now.

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And that is my post, which I get here.

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And now I can set this .title,

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so of this class or of the object that was created based

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on this class equal to post.title,

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so equal to the title I fetched from the database.

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And just to make this clear,

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this is, again, my postDocument.

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So we can use that to clarify that here I got

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back my document from the database.

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And I set this content equal to postDocument.content.

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And then, we could call the fetch method on a post

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that we instantiated with an ID,

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but without a title or content,

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because we're setting this dynamically in here then.

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So then, in blog.js, here,

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we could again create a post by calling new Post.

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We don't need to create the post ID here.

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Instead, we pass null for the title of the content,

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and we pass req.params.id for the ID.

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And then, we call post.fetch here

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to trigger that fetch function we just added

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to use that internally-stored ID

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to fetch all the other data that belongs to this post.

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Now, I will await that, and then thereafter, we continue.

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Now this check here won't do the trick anymore though,

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because now post will always exist,

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but that doesn't necessarily tell us

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whether fetching the data will succeed.

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That's not too problematic though,

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because this check your wasn't

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entirely correct anymore anyways.

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Therefore, here,

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we wanna update this check

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and maybe check if post.title is not set,

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or if not post.content,

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which means we created a post object,

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but we were not able to populate that

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with title and content.

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And there would be other ways

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of implementing this logic as well,

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but this should do the trick.

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And with all of that,

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we now outsourced all our post data-related logic

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into the post model, as it should be.

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Now in blog.js, we can get rid of that import to db,

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and we can get rid of the objectId creation here

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and of the MongoDB import.

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Because that is now all taking place in the post model file.

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And that's the idea behind the post model file.

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Now if I save this, this crashes.

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Let's see what's wrong.

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My mistake.

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When you add a static method, that should be async.

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async has to come after static.

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So it's static async instead of async static.

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We have to swap that.

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So it's static async.

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And with that, if we now reload, that's looking good.

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If I visit the admin page,

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all the posts are still fetched without new errors.

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So that's working.

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And if we view a single post, that fails though,

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and that fails because postId is not defined.

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And that's just a mistake from my side again,

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here in the post model, when we fetch.

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Of course, when I find a post,

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this should not look for postId.

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This doesn't exist here.

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Instead, we wanna use this ID here.

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So same mistake as before, sorry.

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But that is also, I guess, a bit helpful

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because you see that such errors are happening.

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It's easy to overlook something like this,

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and it's always the error messages,

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which you wanna have a look at

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to see why things are failing.

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With that added though, if I now reload,

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populating this forum works correctly again.

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So therefore, now that is working.

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Now there is one change we have to implement though,

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and that is related to how we are fetching a single post.

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We are now doing that with help of this fetch method,

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which we added,

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which populates the existing post object with the data.

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Now there is a subtle issue with that,

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which can be really hard to spot.

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When we rely on this post object based on our post class,

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then the ID of the post is stored

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in an ID property, not _id.

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The implication of that is that in all the places

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where we rely on our own post object

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instead of that document fetched from the database,

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we now must not work with _id anymore,

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but with just ID.

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And in detail, that's the case in our single-post EJS file.

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Here, I'm configuring the submit URL

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for my updating post route.

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And there, I'm accessing post._id.

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Now keep in mind

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that the single-post EJS file is actually rendered

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in this get /posts/:id/edit route.

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And there, I populate post with that post I created here.

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So with my own object based on my own class.

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And therefore, the ID in my own object is not stored

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in a ._id field, but in just a .id.

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So in single-post.ejs, we have to work with just id here.

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Otherwise, we would get an error

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if we do try to update a post.

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This does not affect any other pages

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because in no other pages,

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we send our own class-based object into the view.

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But here we are doing it,

194
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and therefore we need to ensure that we update this

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so that when we reload this detail page,

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and I do update this post here, saving this works.

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Otherwise, it would have failed.

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But that's the only thing.

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A new post can be created without issues

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because there we're not using any ID of any existing object.

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But it was important for updating.

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And with that,

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we now switched to using a model for our posts.

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We can do the same for the auth part here,

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but I will do that later.

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Instead, let's now first move on to the controller part

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and see how we implement that

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and which other refactorings we can apply

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to our post-related routes.