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Sequelize allows you to extend models with additional functionality. Since Sequelize models are ES6 classes, you can easily add custom instance-level methods that encapsulate the functionality. In this video, you'll create helper methods to format an article's publish date and short description.
Code Snippets
publishedAt() {
const date = moment(this.createdAt).format("MMMM D, YYYY, h:mma");
return date;
}
shortDescription() {
const shortDesc = this.body.length > 200 ? this.body.substring(0, 200) + "..." : this.body;
return shortDesc;
}
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Sequelize allows you to extend models
with additional functionality.
0:00
Since Sequelize modules are ES6 classes,
0:04
you can easily add custom instance
methods to encapsulate the functionality.
0:07
In this video, we'll create a published at
helper method which formats the publish or
0:12
created at date and article byline.
0:17
And a short description method that
generates a short description for
0:19
an article when displayed in
the main article listing view.
0:23
Again, these methods will be available
to all model instances created or
0:25
invoked in the context of each model
hence the name instance methods.
0:30
At the top of the models, article.js file,
we'll first require the moment npm
0:35
package, which will bring in the moment.js
library we'll use to format and
0:40
display the publish date for each article.
0:45
Inside the article class,
create a method named publishedAt.
0:55
In the method, declare a variable named
date to store the formatted date.
1:05
Then set it to the moment method.
1:12
We wanna format the created at
timestamp of each model instance.
1:17
So past moment,
this.createdAt as the value to format.
1:22
Then we'll format the timestamp using the
moment libraries format method, like so.
1:28
This will display the publish date
as month, day, year and time.
1:37
Then we'll return the date variable
which holds the formatted date.
1:45
You can copy this exact snippet and
1:53
learn more about the moment.js library
in the teachers notes with this video.
1:55
Next, you access the value returned by
a model instances published at method in
2:00
the view by simply calling the method.
2:05
Open the file, views, articles,
2:07
by-line and replace article.createdAt,
2:12
with article.publishedAt.
2:18
Back in the app,
looking at the main article listing and
2:24
the individual articles,
I see the formatted dates.
2:28
Next, inside the article class,
I'll generate the short article
2:38
description with a method
called short description.
2:42
Inside the method,
declare a variable named shortDesk,
2:49
which will hold the short description.
2:54
I'll limit the short description
to a maximum of 200 characters.
2:57
I'll use a conditional ternary operator
to specify if this.body.length or
3:01
the length of the body property,
is greater than 200.
3:08
Return the portion of the text
starting at the zero character
3:13
index to the 200 character
with this.body.substring (0,
3:19
200) And,
3:25
I want to display an ellipses at the end,
to show that the article is truncated.
3:28
So, I'll concatenate the three dots.
3:32
And, if the body length is
less than 200 characters,
3:36
I'll simply return the full
article with this.body.
3:40
Finally, return the short description
stored in the variable shortDesc.
3:46
You can also copy this method from
the teachers notes with this video and
3:54
learn more about the JavaScript
substring method.
3:58
Next, I'll display the short
description in the index view
4:01
by opening the file views
> articles > index.pug.
4:06
And in type p tag, replace article.body
with a call to article.shortDescription.
4:11
I'll test the short description method,
4:22
by creating a new article titled,
My latest Article, authored by me.
4:26
And I'll paste in body text that's longer
than 200 characters, and click Submit.
4:33
Then click back to the articles listing,
and see that it worked.
4:39
The new article text is shortened,
displaying the ellipses.
4:42
When I click two or more,
I can see the full article.
4:46
In the next video, we'll work on
updating and deleting entries.
4:50
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