html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,issue,performed_via_github_app
https://github.com/simonw/datasette/issues/944#issuecomment-675829942,https://api.github.com/repos/simonw/datasette/issues/944,675829942,MDEyOklzc3VlQ29tbWVudDY3NTgyOTk0Mg==,9599,2020-08-19T03:27:25Z,2020-08-19T03:27:25Z,OWNER,"I created a template file called `templates/pages/museums/{slug}.html` and used the debugger to see if Jinja could see it. This worked:
```
(Pdb) self.ds.jinja_env.list_templates()
['500.html', '_codemirror.html', '_codemirror_foot.html', '_description_source_license.html', '_footer.html',
'_table.html', 'allow_debug.html', 'base.html', 'database.html', 'default:500.html', 'default:_codemirror.html',
'default:_codemirror_foot.html', 'default:_description_source_license.html', 'default:_footer.html',
'default:_table.html', 'default:allow_debug.html', 'default:base.html', 'default:database.html',
'default:index.html', 'default:logout.html', 'default:messages_debug.html', 'default:patterns.html',
'default:permissions_debug.html', 'default:query.html', 'default:row.html', 'default:show_json.html',
'default:table.html', 'forbidden.html', 'index.html', 'logout.html', 'messages_debug.html',
'pages/about.html', 'pages/museums/{slug}.html', 'patterns.html', 'permissions_debug.html',
'query.html', 'row.html', 'show_json.html', 'table.html']
```
The `pages/museums/{slug}.html` template is in that list.

Here's the implementation of that `list_templates()` method - it does some filesystem walking so it may be a bit expensive to run it on every request: https://github.com/pallets/jinja/blob/ca8b0b0287e320fe1f4a74f36910ef7ae3303d99/src/jinja2/loaders.py#L197-L212

But caching it would be pretty easy - either until the server is restarted or as an in-memory cache for a few seconds.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",681516976,
https://github.com/simonw/datasette/issues/944#issuecomment-675830678,https://api.github.com/repos/simonw/datasette/issues/944,675830678,MDEyOklzc3VlQ29tbWVudDY3NTgzMDY3OA==,9599,2020-08-19T03:30:10Z,2020-08-19T03:30:10Z,OWNER,"These templates will need a way to raise a 404 - so that if the template itself is deciding if the page exists (for example using `datasette-template-sql` or the proposed `datasette.get()` method from #943 or the `graphql()` template function in https://github.com/simonw/datasette-graphql/issues/50) it can return a regular 404 page.

This can imitate the `custom_redirect()` function from https://docs.datasette.io/en/stable/custom_templates.html#custom-redirects:
```html+jinja
{{ custom_redirect(""https://github.com/simonw/datasette"", 301) }}
```
It could be as simple as this:
```
{{ raise_404(""Museum not found"") }}
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",681516976,
https://github.com/simonw/datasette/issues/944#issuecomment-691769222,https://api.github.com/repos/simonw/datasette/issues/944,691769222,MDEyOklzc3VlQ29tbWVudDY5MTc2OTIyMg==,9599,2020-09-14T02:01:33Z,2020-09-14T02:01:33Z,OWNER,I'm going to cache the `list_templates()` result in memory. If you want to add a new template-defined route you will need to restart the server. I think that's acceptable.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",681516976,
https://github.com/simonw/datasette/issues/944#issuecomment-691774262,https://api.github.com/repos/simonw/datasette/issues/944,691774262,MDEyOklzc3VlQ29tbWVudDY5MTc3NDI2Mg==,9599,2020-09-14T02:24:08Z,2020-09-14T02:24:08Z,OWNER,"Actually don't need `{{ raise_404(""Museum not found"") }}` because we already have `{{ custom_status(404) }}`.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",681516976,
https://github.com/simonw/datasette/issues/944#issuecomment-691788478,https://api.github.com/repos/simonw/datasette/issues/944,691788478,MDEyOklzc3VlQ29tbWVudDY5MTc4ODQ3OA==,9599,2020-09-14T03:21:45Z,2020-09-14T03:21:45Z,OWNER,Having tried this out I think it does need a `raise_404()` mechanism - which needs to be smart enough to trigger the default 404 handler without accidentally going into an infinite loop.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",681516976,