issue_comments

Got a TIL out of this: https://til.simonwillison.net/pluggy/multiple-hooks-same-file

I managed to extract both _search= and _where= out using a prototype of that hook. I wonder if it could extract the complex code for ?_next too?

Ran into a problem prototyping that hook up for handling ?_where= - that feature also adds a little bit of extra template context in order to show the interface for removing wheres - the extra_wheres_for_ui variable: https://github.com/simonw/datasette/blob/0663d5525cc41e9260ac7d1f6386d3a6eb5ad2a9/datasette/views/table.py#L457-L463

Maybe change to this?

python class FilterArguments(NamedTuple): where_clauses: List[str] params: Dict[str, Union[str, int, float]] human_descriptions: List[str] extra_context: Dict[str, Any] That might be necessary for _search too.

The hook could return a named tuple like this one: ```python from typing import NamedTuple, List, Optional, Union, Dict

class FilterArguments(NamedTuple): where_clauses: List[str] params: Dict[str, Union[str, int, float]] human_descriptions: List[str] ```

I think that plugin hook would get given the request object (and datasette and the name of the database and table) and returns a list of SQL fragments, a dictionary of lookup arguments and a list of human-description fragments - or an awaitable.

filters_from_request(request, database, table, datasette) perhaps? (Similar in name to actor_from_request).

python @hookspec def filters_from_request(request, database, table, datasette): """Return (where_clauses, params_dict, human_descriptions) based on the request"""

Turns out that's pretty much exactly what I implemented in 5116c4ec8aed5091e1f75415424b80f613518dc6 for #473:

```python

@hookspec def table_filter(): "Custom filtering of the current table based on the request" python TableFilter = namedtuple("TableFilter", ( "human_description_extras", "where_clauses", "params") ) python # filter_arguments plugin hook support for awaitable_fn in pm.hook.table_filter(): extras = await awaitable_fn( view=self, name=name, table=table, request=request ) human_description_extras.extend(extras.human_description_extras) where_clauses.extend(extras.where_clauses) params.update(extras.params) ```

Is there an opportunity to refactor things using a new plugin hook here? Maybe the register_filters hook from #473, where the hook becomes responsible for building where clauses (and human descriptions of them) based on the incoming query string.

That version dealt with Filter classes, but those might be a bit too low-level for this.

?_spatial_within=GEOJSON was an interesting idea attached to that issue.

I added a ton of comments to the data() method which really helps get a better feel for how this all works: https://github.com/simonw/datasette/blob/0663d5525cc41e9260ac7d1f6386d3a6eb5ad2a9/datasette/views/table.py#L322

A fundamental operation of this view is to construct the SQL query and accompanying human description based on the incoming query string parameters.

The human description is the bit at the top of https://latest.datasette.io/fixtures/searchable?_search=dog&_sort=pk&_facet=text2&text2=sara+weasel that says:

1 row where search matches "dog" and text2 = "sara weasel" sorted by pk

(Also used in the page <title>).

The code actually gathers three things:

• Fragments of the where clause, for example "text2" = :p0
• Parameters, e.g. {"p0": "sara weasel"}
• Human description components, e.g. text2 = "sara weasel"

Some operations such as ?_where= don't currently provide an extra human description component.

_where= also doesn't populate a parameter, but maybe it could? Would be neat if in the future ?_where=foo+=+:bar worked and added a bar input field to the screen, as seen with custom queries.

Should facets really not be displayed on pages past page one (where ?_next= is set)? That made sense to me at the time, but I'm now having second thoughts about it.

I guess it's a useful performance tweak for when crawlers keep hitting the ?_next= link.

Actually it looks like facets DO display on subsequent pages, e.g. on https://global-power-plants.datasettes.com/global-power-plants/global-power-plants?_next=200 - but facet suggestions do not, thanks to this code: https://github.com/simonw/datasette/blob/2c07327d23d9c5cf939ada9ba4091c1b8b2ba42d/datasette/views/table.py#L777-L785