Hi,
Since the latest Discourse 2.5.0 version, I have trouble with thumbnails generation.
It seems thumbnails are now generated from core, and it resulted in all thumbnails being wiped.
I tried various operations to put them back and Iโm going to explain situations where it doesnโt work.
Note: there is probably a good reason for that change, but that would be really welcomed to not introduce sudden behavior change breaking functionality without having a way to be prepared, with an upgrade guide and/or a way to opt in this change, please. 
Context
- Discourse 2.5.0 beta4 (faeb5793ba)
- Topic List Preview plugin 4.4.0
- WP-Discourse Posts published at it is (full HTML) on Discourse topics (first message).
About a post content, this is an example (formatted for you):
Content
Image HTML as code for convenience:
<img
width="150"
height="84"
src="https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช-150x84.jpg"
class="attachment-thumbnail size-thumbnail"
alt=""
srcset="
https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช-150x84.jpg 150w,
https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช-300x169.jpg 300w,
https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช-1200x675.jpg 1200w,
https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช-1536x864.jpg 1536w,
https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช-2048x1152.jpg 2048w,
https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช-788x443.jpg 788w,
https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช.jpg 1280w
"
sizes="(max-width: 150px) 100vw, 150px"
/>
<div data-wp>
<a
href="https://www.banggood.com/Xiaomi-Redmi-Router-AC2100-2033Mbps-2_4G-5G-Dual-Band-Wireless-Router-6High-Gain-Antennas-128MB-OpenWRT-WiFi-Router-p-1614038.html"
target="_blank"
><img src="https://zuzu.deals/wp-content/uploads/2020/01/5e3128b4e5da7-150x150.jpg"/>
</a>
<div>
<div data-buy>
<a
href="https://www.banggood.com/Xiaomi-Redmi-Router-AC2100-2033Mbps-2_4G-5G-Dual-Band-Wireless-Router-6High-Gain-Antennas-128MB-OpenWRT-WiFi-Router-p-1614038.html"
target="_blank">ืงื ืืื
</a>
<span data-clipboard-text="BG38b2ac" data-coupon>BG38b2ac</span><i></i>
</div>
<div data-price>$43.99</div>
</div>
</div>
<hr />
<p>
<small>
ืคืืจืกื ื: <a href="https://zuzu.deals/%d7%a7%d7%95%d7%a4%d7%95%d7%9f-%d7%91%d7%9c%d7%a2%d7%93%d7%99-%d7%a8%d7%90%d7%95%d7%98%d7%a8-%d7%97%d7%96%d7%a7-%d7%95%d7%97%d7%93%d7%a9-%d7%a9%d7%9c-%d7%a9%d7%99%d7%90%d7%95%d7%9e%d7%99-xiaomi-re-2/"></a>
</small>
</p>
<br />
<p>ื ืขืื ืืืืืจ!</p>
Before Discourse update
TLP worked always well on our external images, whatever on topic creation or edition.
However, we had the download remote images to local option disabled because of markdown issue.
Markdown rendering issue
This not the main issue, and it still happens after Discourse upgrade, here some explanation.
When discourse downloads and replaces an image HTML with its markdown syntax โ in our context, this results as:
[...]<a href="<link_here>" target="_blank"></a>[...]
Discourse is unable to render the image
Image
To fix the issue, you need at least an empty line above:
[...]<a href="<link_here>" target="_blank">
</a>[...]
Image
Would it be possible to allow rendering markdown image surrounded by HTML, please?
After Discourse update
- All thumbnails got deleted.
- All images are well displayed in the topic content
- Because of this feature (https://github.com/discourse/discourse/commit/03818e642a1ae871bffdc0c39c10f05f0b8b0398, I think), we were forced to enable
download remote images to localoption as it would appear this no more possible to get a thumbnail from external linkโฆ
-
download remote images max days oldis set to the max, 10000.
From this, I was told to rebake all posts to get the image downloaded. And itโs where it gets weird.
-
rake posts:rebakedid not have much effect (at least not on the first message of a topic, but it did trigger a lot ofPullHotlinkedImages)
1.1. Looking at some topics, I thought that the image HTML withclassorsrcsetattributes were the cause, so I tried to normalize all the images with the following code (donโt know ruby) โ It helped for some topics.
1.2. However due to the markdown issue, I had to add newlines to fix. โ At least for those topics, thumbnail worked.
Code
Post.where(post_number: 1)
.where("raw LIKE '%<img%/>%'")
.each
do |post|
post.raw.gsub!(/<img[^>]+(src="[^"]+")[^>]+\/>/, "<img \\1 />")
post.save!(validate: true)
post.rebake!
end
Post
.where(post_number: 1)
.where("raw LIKE '%upload://%'").each
do |post|
post.raw.gsub!(/(!\[.*upload:\/\/.*\))/, "\n\n\\1")
post.save!(validate: false);
post.rebake!
end
- Editing manually (without changing content, just saving) an ignored topic works most of the time. Image is downloaded.
2.1. Some topic are ignored even after an edit. I can seePullHotlinkedImagesis triggered but no images are downloaded. (like with this html<img src="https://zuzu.reviews/wp-content/uploads/2020/05/HiZERO-VS-BISSEL-VS-ืฉืืื-ืืืืืื-VS-ืฉืืื-ืจืืืืื-VS-ืืื-ืืืื-VS-ืืืืื-VS-ืกืคืื ืื-ืืฉืืืืช-150x84.jpg" />, link) - After normalizing, and seeing that an edit can help to download the image, I tried to
rake posts:rebakemultiple times โ without effects. - Then I tried to use the rails console similar to the code above but with specific topic id and with only
post.rebake!โ without effects - Not all images from a topic are always downloadedโฆ
- @Canapin points me to Download remote images from older posts? - #3 by vinothkannans ; trying to rebake all posts now. โ Did not help unfortunately
Itโs just crazy why some images works, others not. I donโt think itโs a criteria issue. Image settings are high. I really donโt understand what is the logic behind, this seems random.
Currently, we have still a lot of missing thumbnails. Likely most of them can be fixed manually with editing/saving, but thatโs not feasible. Iโm doing that for a client, and I have lost already a lot of time trying to fix the issue.
I donโt mind having upload images as thumbnail, but:
- Can you tell me if there are specific reasons why images wonโt download? Are there settings which can help? Do we need something? How to debug?
- Is there a way to force download them similar to editing/saving through the console?
- Can you allow markdown image rendering if surrounded by HTML?
Hopefully I was enough precise in the problem description.
Thanks in advance for any help and solution.
(category change)
(Me 
(system replacing image with markdown)