Adding Comments Part 3: Existing Posts
This is part of a series on building my own comment engine for Hugo. You can start with part 1.
Last time, we made changes to the file at
archetypes/posts.md
so that hugo will generate a unique ID for each post. But I already
have a number of posts, and I want to make sure that they get IDs as well. So this
post is about writing a once off shell script or similar to add new IDs to these existing
posts.
I found a post about using sed
to insert a line after a match,
which is just about what I need to do. So let’s take a look at this shell script. (For those
of you following along at home, I use zsh
, not bash, so if there’s something weird, that
might be why). One good thing is that everything is under version control, so if I screw this
up, I can always go back, which is nice. So before I start, I’m going to make sure everythinng
is set committed :)
All my posts have a line like draft: true
or draft: false
in the front matter, so we should be
able to use that.
Let’s start with a find command to list all the posts:
$ find ./content/posts -name '*.md'
./content/posts/hugo-workflow.md
./content/posts/primeversary-state-machine.md
./content/posts/adding-comments-3-existing-posts.md
./content/posts/science-journalism-and-cherry-picking-cases.md
... # snip
Now, let’s try to get the sed
command right one one post before we try running it on
all the posts.
It seems that macOS sed
is different from GNU sed
,
so we’ll start with a brew install
to get the better-documented GNU sed
:
$ brew install gnu-sed
$ gsed -i '/^draft:/a some-string: foo/' content/posts/hugo-workflow.md
$ git diff content/posts/hugo-workflow.md
produces:
diff --git a/content/posts/hugo-workflow.md b/content/posts/hugo-workflow.md
index 4f2c23a..5675862 100644
--- a/content/posts/hugo-workflow.md
+++ b/content/posts/hugo-workflow.md
@@ -2,6 +2,7 @@
title: "Hugo Workflow"
date: 2022-01-09T05:16:30-05:00
draft: false
+some-string: foo
layout: single
---
---
great, so that adds some-string: foo
to the front matter.
Now let’s try generating an md5 of the path as we go:
# first, get the hash command right:
$ md5 -q -s content/posts/hugo-workflow.md # -q: quiet, -s: input is string, not path
f6e23ced7418aa38d4f19e73fea380d1
$ gsed -i "/^draft:/a post_id: $(md5 -q -s content/posts/hugo-workflow.md)" content/posts/hugo-workflow.md
$ git diff content/posts/hugo-workflow.md
...
+post_id: f6e23ced7418aa38d4f19e73fea380d1
This uses a different format than Hugo (it looks like it prints as a hex number instead of as a base-ten number), but these are just IDs. As long as they’re different from each other, I really don’t care. To the application, they’re just opaque strings with the only requirements that they are unique and stable.
Now lets try to glue this together with find -exec
which, to be honest, I always screw up at least a bit.
$ find content/posts -name '*.md' -exec bash -c 'POST={}; gsed -i "/^draft:/a post_id: $(md5 -q -s $POST)" $POST \;
I have to use -exec bash -c
so make find
able to execute the more complicated command.
And do we have victory?
diff --git a/content/posts/adding-comment-capability.md b/content/posts/adding-comment-capability.md
index c5f8776..dca7fa9 100644
--- a/content/posts/adding-comment-capability.md
+++ b/content/posts/adding-comment-capability.md
@@ -2,6 +2,7 @@
title: "Adding Comment Capability"
date: 2022-01-18T06:09:24-05:00
draft: false
+post_id: 40c2e7cef071f8c3fe397b1b0706121d
layout: single
---
diff --git a/content/posts/adding-comments-2-post-ids.md b/content/posts/adding-comments-2-post-ids.md
index 2b72edf..080c986 100644
--- a/content/posts/adding-comments-2-post-ids.md
+++ b/content/posts/adding-comments-2-post-ids.md
@@ -2,6 +2,7 @@
title: "Adding Comments Part 2: Post IDs"
date: 2022-01-19T03:30:48-05:00
draft: false
+post_id: 474009447dc18cbf7c97173d628a2409
layout: single
---
Let’s make sure that everything has a unique post ID, since on my first version I message that up, and everything ended up with the same MD5.
$ grep -r 'post_id:' content/posts | rev | cut -d ' ' -f 1 | rev | sort | uniq -c
1 0421c363b141633403a253ea6d9c30a0
1 22d8fe126df6bcf225c28ab3b7417156
1 2e9bd3a6d0ede8423cd3e556d36a70c1
Prints a bunch of lines starting with 1
. The only lines that don’t start with 1 are the two that
appear in the git diff
output pasted above.
Now that I’ve run my one-time script, I can just commit those changes, plus the changes to archetypes.md, and I’ll have unique IDs on all the posts. Next time, we’ll figure out how to ship these IDs down to the client side.
Till then, happy learning!
– Will
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