Build a tag index page

Now that you have individual pages for every tag, it’s time to make links to them.

Get ready to…

Add a new page using the /pages/folder/index.astro routing pattern
Display a list of all your unique tags, linking to each tag page
Update your site with navigation links to this new Tags page

Use the `/pages/folder/index.astro` routing pattern

To add a Tag Index page to your website, you could create a new file at src/pages/tags.astro.

But, since you already have the directory /tags/, you can take advantage of another routing pattern in Astro, and keep all your files related to tags together.

Try it yourself - Make a Tag Index page

Create a new file index.astro in the directory src/pages/tags/.
Navigate to http://localhost:4321/tags and verify that your site now contains a page at this URL. It will be empty, but it will exist.
Create a minimal page at src/pages/tags/index.astro that uses your layout. You have done this before!
Expand to see the steps
1. Create a new page component in src/pages/tags/.
  Show the filename
  index.astro
2. Import and use your <BaseLayout>.
  Show the code
  src/pages/tags/index.astro
  --- import BaseLayout from '../../layouts/BaseLayout.astro'; --- <BaseLayout></BaseLayout>
3. Define a page title, and pass it to your layout as a component attribute.
  Show the code
  src/pages/tags/index.astro
  --- import BaseLayout from '../../layouts/BaseLayout.astro'; const pageTitle = "Tag Index"; --- <BaseLayout pageTitle={pageTitle}></BaseLayout>
Check your browser preview again and you should have a formatted page, ready to add content to!

Create an array of tags

You have previously displayed items in a list from an array using map(). What would it look like to define an array of all your tags, then display them in a list on this page?

See the code

---
import BaseLayout from '../../layouts/BaseLayout.astro';
const tags = ['astro', 'blogging', 'learning in public', 'successes', 'setbacks', 'community']
const pageTitle = "Tag Index";
---
<BaseLayout pageTitle={pageTitle}>
  <ul>
    {tags.map((tag) => <li>{tag}</li>)}
  </ul>
</BaseLayout>

You could do this, but then you would need to come back to this file and update your array every time you use a new tag in a future blog post.

Fortunately, you already know a way to grab the data from all your Markdown files in one line of code, then return a list of all your tags.

In src/pages/tags/index.astro, add the line of code to the frontmatter script that will give your page access to the data from every .md blog post file.

See the code

---
import BaseLayout from '../../layouts/BaseLayout.astro';
const allPosts = Object.values(await import.meta.glob('../posts/*.md', { eager: true }));
const pageTitle = "Tag Index";
---

Next, add the following line of JavaScript to your page component. This is the same code relying on Astro’s built-in TypeScript support you used in src/pages/tags/[tag].astro to return a list of unique tags.

---
import BaseLayout from '../../layouts/BaseLayout.astro';
const allPosts = Object.values(await import.meta.glob('../posts/*.md', { eager: true }));
const tags = [...new Set(allPosts.map((post: any) => post.frontmatter.tags).flat())];
const pageTitle = "Tag Index";
---

Create your list of tags

Instead of creating items in an unordered list this time, create one <p> for each item, inside a <div>. The pattern should look familiar!

Add the following code to your component template:
src/pages/tags/index.astro
```
<BaseLayout pageTitle={pageTitle}>
  <div>{tags.map((tag) => <p>{tag}</p>)}</div>
</BaseLayout>
```
In your browser preview, verify that you can see your tags listed. If any blog posts are missing tags, or they are improperly formatted, Astro’s built-in TypeScript support will show you errors so you can check and correct your code.

To make each tag link to its own page, add the following <a> link to each tag name:

<BaseLayout pageTitle={pageTitle}>
  <div>
    {tags.map((tag) => (
      <p><a href={`/tags/${tag}`}>{tag}</a></p>
    ))}
  </div>
</BaseLayout>

Add the following CSS classes to style both your <div> and each <p> that will be generated. Note: Astro uses HTML syntax for adding class names!

<BaseLayout pageTitle={pageTitle}>
  <div class="tags">
    {tags.map((tag) => (
      <p class="tag"><a href={`/tags/${tag}`}>{tag}</a></p>
    ))}
  </div>
</BaseLayout>

Define these new CSS classes by adding the following <style> tag to this page:

<style>
  a {
    color: #00539F;
  }

  .tags {
    display: flex;
    flex-wrap: wrap;
  }

  .tag {
    margin: 0.25em;
    border: dotted 1px #a1a1a1;
    border-radius: .5em;
    padding: .5em 1em;
    font-size: 1.15em;
    background-color: #F8FCFD;
  }
</style>

Check your browser preview at http://localhost:4321/tags to verify that you have some new styles and that each of the tags on the page has a working link to its own individual tag page.

Code Check-In

Here is what your new page should look like:

---
import BaseLayout from '../../layouts/BaseLayout.astro';
const allPosts = Object.values(await import.meta.glob('../posts/*.md', { eager: true }));
const tags = [...new Set(allPosts.map((post) => post.frontmatter.tags).flat())];
const pageTitle = "Tag Index";
---
<BaseLayout pageTitle={pageTitle}>
  <div class="tags">
    {tags.map((tag) => (
      <p class="tag"><a href={`/tags/${tag}`}>{tag}</a></p>
    ))}
  </div>
</BaseLayout>
<style>
  a {
    color: #00539F;
  }

  .tags {
    display: flex;
    flex-wrap: wrap;
  }

  .tag {
    margin: 0.25em;
    border: dotted 1px #a1a1a1;
    border-radius: .5em;
    padding: .5em 1em;
    font-size: 1.15em;
    background-color: #F8FCFD;
  }
</style>

Right now, you can navigate to http://localhost:4321/tags and see this page. From this page, you can click on links to your individual tag pages.

But, you still need to make these pages discoverable from other pages on your website.

In your Navigation.astro component, include a link to this new tag index page.
Show me the code
src/components/Navigation.astro
```
<a href="/">Home</a>
<a href="/about/">About</a>
<a href="/blog/">Blog</a>
<a href="/tags/">Tags</a>
```

Challenge: Include tags in your blog post layout

You have now written all the code you need to also display a list of tags on each blog post, and link them to their tag pages. You have existing work that you can reuse!

Follow the steps below, then check your work by comparing it to the final code sample.

Copy the <div class="tags">...</div> and <style>...</style> from src/pages/tags/index.astro and reuse it inside MarkdownPostLayout.astro:

---
import BaseLayout from './BaseLayout.astro';
const { frontmatter } = Astro.props;
---
<BaseLayout pageTitle={frontmatter.title}>
  <p><em>{frontmatter.description}</em></p>
  <p>{frontmatter.pubDate.toString().slice(0,10)}</p>

  <p>Written by: {frontmatter.author}</p>

  <img src={frontmatter.image.url} width="300" alt={frontmatter.image.alt} />

  <div class="tags">
    {tags.map((tag: string) => (
      <p class="tag"><a href={`/tags/${tag}`}>{tag}</a></p>
    ))}
  </div>

  <slot />
</BaseLayout>
<style>
  a {
    color: #00539F;
  }

  .tags {
    display: flex;
    flex-wrap: wrap;
  }

  .tag {
    margin: 0.25em;
    border: dotted 1px #a1a1a1;
    border-radius: .5em;
    padding: .5em 1em;
    font-size: 1.15em;
    background-color: #F8FCFD;
  }
</style>

Before this code will work, you need to make one small edit to the code you pasted into MarkdownPostLayout.astro. Can you figure out what it is?

Give me a hint

How are the other props (e.g. title, author, etc.) written in your layout template? How does your layout receive props from an individual blog post?

Give me another hint!

In order to use props (values passed) from a .md blog post in your layout, like tags, you need to prefix the value with a certain word.

Show me the code!

    <div class="tags">
      {frontmatter.tags.map((tag: string) => (
        <p class="tag"><a href={`/tags/${tag}`}>{tag}</a></p>
      ))}
    </div>

Code Check-in: MarkdownPostLayout

To check your work, or if you just want complete, correct code to copy into MarkdownPostLayout.astro, here is what your Astro component should look like:

---
import BaseLayout from './BaseLayout.astro';
const { frontmatter } = Astro.props;
---
<BaseLayout pageTitle={frontmatter.title}>
  <p><em>{frontmatter.description}</em></p>
  <p>{frontmatter.pubDate.toString().slice(0,10)}</p>

  <p>Written by: {frontmatter.author}</p>

  <img src={frontmatter.image.url} width="300" alt={frontmatter.image.alt} />

  <div class="tags">
    {frontmatter.tags.map((tag) => (
      <p class="tag"><a href={`/tags/${tag}`}>{tag}</a></p>
    ))}
  </div>

  <slot />
</BaseLayout>
<style>
  a {
    color: #00539F;
  }

  .tags {
    display: flex;
    flex-wrap: wrap;
  }

  .tag {
    margin: 0.25em;
    border: dotted 1px #a1a1a1;
    border-radius: .5em;
    padding: .5em 1em;
    font-size: 1.15em;
    background-color: #F8FCFD;
  }
</style>

Checklist

I can use Astro’s /pages/folder/index.astro routing feature.

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Build a tag index page

Use the `/pages/folder/index.astro` routing pattern

Try it yourself - Make a Tag Index page

Create an array of tags

Create your list of tags

Code Check-In

Add this page to your navigation

Challenge: Include tags in your blog post layout

Code Check-in: MarkdownPostLayout

Test your knowledge

Checklist

Resources

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Build a tag index page

Use the /pages/folder/index.astro routing pattern

Try it yourself - Make a Tag Index page

Create an array of tags

Create your list of tags

Add styles to your tag list

Code Check-In

Add this page to your navigation

Challenge: Include tags in your blog post layout

Code Check-in: MarkdownPostLayout

Test your knowledge

Checklist

Resources

Use the `/pages/folder/index.astro` routing pattern