Setting the post id based on the folder name.

src/blog_post/definition.rs

@@ -17,6 +17,10 @@ impl BlogPost {
         post_dir: P,
     ) -> Result<BlogPost, CustomError> {
         async fn inner(root_dir: &Path, post_dir: &Path) -> Result<BlogPost, CustomError> {
+            let post_id = post_dir
+                .file_name()
+                .expect("The post directory should have a name.");
+
             let org_files = {
                 let mut ret = Vec::new();
                 let org_files_iter = get_org_files(post_dir)?;
@@ -36,7 +40,7 @@ impl BlogPost {
             };
 
             Ok(BlogPost {
-                id: "foo".to_owned(),
+                id: post_id.to_string_lossy().into_owned(),
             })
         }
         inner(root_dir.as_ref(), post_dir.as_ref()).await