Link to BLOB downloads

[simonw]

As added to Datasette in simonw/datasette#1036

Blocked awaiting release of Datasette 0.51.

[simonw]

I should use row_blob() and document it:

• Documentation and unit tests for urls.row() urls.row_blob() methods datasette#1048

[simonw]

I can ship this against the new 0.51a1 release.

[simonw]

Interface with the plugin installed:

Without:

[simonw]

This will be easier after the next Datasette release since it adds the row to the render_cell plugin hook:

• Make row available to render_cell plugin hook datasette#1300

[simonw]

Blocked on that release.

[simonw]

https://github.com/simonw/datasette/releases/tag/0.62 is out, unblocking this.

[simonw]

Here's the code in Datasette core that renders the <Binary: x bytes> link:

https://github.com/simonw/datasette/blob/5aa359b86907d11b3ee601510775a85a90224da8/datasette/views/table.py#L934-L948

                display_value = markupsafe.Markup(
                    '<a class="blob-download" href="{}"{}>&lt;Binary:&nbsp;{:,}&nbsp;byte{}&gt;</a>'.format(
                        datasette.urls.row_blob(
                            database_name,
                            table_name,
                            path_from_row_pks(row, pks, not pks),
                            column,
                        ),
                        ' title="{}"'.format(formatted)
                        if "bytes" not in formatted
                        else "",
                        len(value),
                        "" if len(value) == 1 else "s",
                    )
                )

[simonw]

I need pks, which can be found like this:

        pks = await db.primary_keys(table_name)

But I really don't want to run that for every single time the render_cell hook is called.

[simonw]

I'm tempted to add pks to the list of arguments to the render_cell() hook in Datasette core.

One catch there though: it's not available for arbitrary database queries, but those need to be supported by this plugin too - like this: https://latest.datasette.io/_memory?sql=select+X%2753514C697465%27

Here's how that works: https://github.com/simonw/datasette/blob/5aa359b86907d11b3ee601510775a85a90224da8/datasette/views/database.py#L409-L430

                        elif isinstance(display_value, bytes):
                            blob_url = path_with_format(
                                request=request,
                                format="blob",
                                extra_qs={
                                    "_blob_column": column,
                                    "_blob_hash": hashlib.sha256(
                                        display_value
                                    ).hexdigest(),
                                },
                            )
                            formatted = format_bytes(len(value))
                            display_value = markupsafe.Markup(
                                '<a class="blob-download" href="{}"{}>&lt;Binary:&nbsp;{:,}&nbsp;byte{}&gt;</a>'.format(
                                    blob_url,
                                    ' title="{}"'.format(formatted)
                                    if "bytes" not in formatted
                                    else "",
                                    len(value),
                                    "" if len(value) == 1 else "s",
                                )
                            )

[simonw]

This code is all complex enough that I think I need to refactor it in Datasette core so I can reuse that here, rather than re-implementing some pretty gnarly Datasette internals just for this plugin.