id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,pull_request,body,repo,type,active_lock_reason,performed_via_github_app,reactions,draft,state_reason
625930207,MDU6SXNzdWU2MjU5MzAyMDc=,770,register_output_renderer can_render mechanism,9599,closed,0,,5471110,4,2020-05-27T18:29:14Z,2020-05-28T05:57:16Z,2020-05-28T05:57:16Z,OWNER,,"I would like is the ability for renderers to opt-in / opt-out of being displayed as options on the page.

https://www.niche-museums.com/browse/museums for example shows a atom link because the datasette-atom plugin is installed... but clicking it will give you a 400 error because the correct columns are not present.

<img width=""1113"" alt=""browse__museums__102_rows"" src=""https://user-images.githubusercontent.com/9599/83058543-62278e80-a00d-11ea-9e04-298e02745118.png"">

Here's the code that passes a list of renderers to the template:

https://github.com/simonw/datasette/blob/2d099ad9c657d2cab59de91cdb8bfed2da236ef6/datasette/views/base.py#L411-L423

A renderer is currently defined as a two-key dictionary:
```python
@hookimpl
def register_output_renderer(datasette):
    return {
        'extension': 'test',
        'callback': render_test
    }
```
I can add a third key, `""should_suggest""` which is a function that returns `True` or `False` for a given query. If that key is missing it is assumed to return `True`.

One catch: what arguments should be passed to the `should_suggest(...)` function?

UPDATE: now calling it `can_render` instead.

_Originally posted by @simonw in https://github.com/simonw/datasette/issues/581#issuecomment-634856748_",107914493,issue,,,"{""url"": ""https://api.github.com/repos/simonw/datasette/issues/770/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed