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
860625833,MDU6SXNzdWU4NjA2MjU4MzM=,1300,Make row available to `render_cell` plugin hook,3243482,closed,0,,,5,2021-04-18T10:14:37Z,2022-07-07T16:34:05Z,2022-07-07T16:31:22Z,CONTRIBUTOR,,"*Original title: **Generating URL for a row inside `render_cell` hook***

Hey,
I am using Datasette to view a database that contains video metadata. It has BLOB columns that contain video thumbnails in JPG format (around 100-500KB per row). 

I've registered an output formatter that extends `datasette.blob_renderer.render_blob` function and serves the column with `image/jpeg` content type.

```python
from datasette.blob_renderer import render_blob

async def render_jpg(datasette, database, rows, columns, request, table, view_name):
    response = await render_blob(datasette, database, rows, columns, request, table, view_name)
    response.content_type = ""image/jpeg""
    response.headers[""Content-Disposition""] = f'inline; filename=""image.jpg""'
    return response


@hookimpl
def register_output_renderer():
    return {
        ""extension"": ""jpg"",
        ""render"": render_jpg,
        ""can_render"": lambda: True,
    }
```

This works well. I can visit `http://localhost:8001/mydb/videos/1.jpg?_blob_column=thumbnail` and view the image.

I want to display the image directly with an `<img>` tag (lazy-loaded of course). So, I need a URL, because embedding base64 would increase the page size too much (each image > 100KB). 

Datasette generates a link with `.blob` extension for blob columns. It does this by calling `datasette.urls.row_blob`

https://github.com/simonw/datasette/blob/7a2ed9f8a119e220b66d67c7b9e07cbab47b1196/datasette/views/table.py#L169-L179

But I have no way of getting the row inside the `render_cell` hook. 

```python
@hookimpl
def render_cell(value, column, table, database, datasette):
    if isinstance(value, bytes) and imghdr.what(None, value):
        # generate url
        return '$renderedLink'
```

Any pointers?",107914493,issue,,,"{""url"": ""https://api.github.com/repos/simonw/datasette/issues/1300/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed