Create a blog post archive

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Now that you have a few blog posts to link to, it’s time to configure the Blog page to create a list of them automatically!

準備好……

Access data from all your posts at once using Astro.glob()
Display a dynamically generated list of posts on your Blog page
Refactor to use a <BlogPost /> component for each list item

Dynamically display a list of posts

Add the following code to blog.astro to return information about all your Markdown files. Astro.glob() will return an array of objects, one for each blog post.

---
import BaseLayout from '../layouts/BaseLayout.astro'
const allPosts = await Astro.glob('./posts/*.md');
const pageTitle = "My Astro Learning Blog";
---
<BaseLayout pageTitle={pageTitle}>
  <p>This is where I will post about my journey learning Astro.</p>
  <ul>
    <li><a href="/posts/post-1/">Post 1</a></li>
    <li><a href="/posts/post-2/">Post 2</a></li>
    <li><a href="/posts/post-3/">Post 3</a></li>
  </ul>
</BaseLayout>

To generate the entire list of posts dynamically, using the post titles and URLs, replace your individual <li> tags with the following Astro code:

---
import BaseLayout from '../layouts/BaseLayout.astro'
const allPosts = await Astro.glob('./posts/*.md');
const pageTitle = "My Astro Learning Blog";
---
<BaseLayout pageTitle={pageTitle}>
  <p>This is where I will post about my journey learning Astro.</p>
  <ul>
    <li><a href="/posts/post-1/">Post 1</a></li>
    <li><a href="/posts/post-2/">Post 2</a></li>
    <li><a href="/posts/post-3/">Post 3</a></li>

    {allPosts.map((post) => <li><a href={post.url}>{post.frontmatter.title}</a></li>)}
  </ul>
</BaseLayout>

Your entire list of blog posts is now being generated dynamically, by mapping over the array returned by Astro.glob().

Add a new blog post by creating a new post-4.md file in src/pages/posts/ and adding some Markdown content. Be sure to include at least the frontmatter properties used below.

---
layout: ../../layouts/MarkdownPostLayout.astro
title: My Fourth Blog Post
author: Astro Learner
description: "This post will show up on its own!"
image:
    url: "https://docs.astro.build/default-og-image.png"
    alt: "The word astro against an illustration of planets and stars."
pubDate: 2022-08-08
tags: ["astro", "successes"]
---
This post should show up with my other blog posts, because `Astro.glob()` is returning a list of all my posts in order to create my list.

Revisit your blog page in your browser preview at http://localhost:4321/blog and look for an updated list with four items, including your new blog post!

Challenge: Create a BlogPost component

Try on your own to make all the necessary changes to your Astro project so that you can instead use the following code to generate your list of blog posts:

<ul>
  {allPosts.map((post) => <li><a href={post.url}>{post.frontmatter.title}</a></li>)}
  {allPosts.map((post) => <BlogPost url={post.url} title={post.frontmatter.title} />)}
</ul>

Expand to see the steps

Create a new component in src/components/.
Show the filename
```
BlogPost.astro
```
Write the line of code in your component so that it will be able to receive a title and url as Astro.props.
Show the code
src/components/BlogPost.astro
```
---
const { title, url } = Astro.props;
---
```
Add the templating used to create each item in your blog post list.
Show the code
src/components/BlogPost.astro
```
<li><a href={url}>{title}</a></li>
```

Import the new component into your Blog page.

Show the code

---
import BaseLayout from '../layouts/BaseLayout.astro';
import BlogPost from '../components/BlogPost.astro';
const allPosts = await Astro.glob('../pages/posts/*.md');
const pageTitle = "My Astro Learning Blog";
---

Check Yourself: see the finished component code.

Show the code

---
const { title, url } = Astro.props
---
<li><a href={url}>{title}</a></li>

---
import BaseLayout from '../layouts/BaseLayout.astro';
import BlogPost from '../components/BlogPost.astro';
const allPosts = await Astro.glob('../pages/posts/*.md');
const pageTitle = "My Astro Learning Blog"
---
<BaseLayout pageTitle={pageTitle}>
  <p>This is where I will post about my journey learning Astro.</p>
  <ul>
    {allPosts.map((post) => <BlogPost url={post.url} title={post.frontmatter.title} />)}
  </ul>
</BaseLayout>

Test your knowledge

If your Astro component contains the following line of code:

---
const myPosts = await Astro.glob('./posts/*.md');
---

Choose the syntax you could write to represent:

The title of your third blog post.
1. myPosts.map((post) => <LastUpdated date={post.frontmatter.pubDate} />)
2. myPosts[2].frontmatter.title
3. <a href={myPosts[0].url}>First Post!!</a>
A link to the URL of your first blog post.
1. myPosts.map((post) => <LastUpdated date={post.frontmatter.pubDate} />)
2. myPosts[2].frontmatter.title
3. <a href={myPosts[0].url}>First Post!!</a>
A component for each post, displaying the date that it was last updated.
1. myPosts.map((post) => <LastUpdated date={post.frontmatter.pubDate} />)
2. myPosts[2].frontmatter.title
3. <a href={myPosts[0].url}>First Post!!</a>