Idea: expose Datasette faceting in GraphQL

[simonw]

Maybe something like this:

{
  repos(filters: ["license=apache-2.0", "stargazers_count__gt=10"]) {
    facet_by_owner {
      node {
        id
        full_name
      }
      name
      count
      where_clause
  }
}

[simonw]

where_clause would return a "owner=1234" string which you can add to that filters: list to select the facet. count would return the count for the facet. node would be the full related object (if a foreign key) - or you can just use name for things that don't have an associated object.

[simonw]

Would this be nicer?

{
  repos(filters: ["license=apache-2.0", "stargazers_count__gt=10"]) {
    facets {
      owner {
        node {
          id
          full_name
        }
        name
        count
        where_clause
      }
    }
  }
}

[simonw]

Challenge: we need to know which facets have been selected when we resolve that root repos node, since we need to know what _facet= arguments should be passed to the underlying TableView.

[simonw]

It looks like the info argument passed to resolve_table can be used to inspect the AST for the current GraphQL query:

(Pdb) info.operation.selection_set.selections[0].selection_set.selections[0].name
Name(value='totalCount')
(Pdb) info.operation.selection_set.selections[0].selection_set.selections[0].name.value
'totalCount'

[simonw]

Unfortunately it doesn't look like that's covered in the documentation, so I'll have to reverse engineer it to figure this out.

[simonw]

Even with the new filters design from #25 I still think the best way to provide the where_clause (the bit that says "if you want to select this filter, here's how to do it) will be to return a string that gets passed to where:.

One catch: what if you are faceting against a query that already used a where: clause? I think the easiest thing there would be to combine that where: clause into the one that is returned in where_clause using an AND.

[simonw]

Or maybe the apply facet value is the query string fragment that gets passed to the underlying JSON API. That would be compatible with things like JSON facets.

This could be passed as a new facet: argument perhaps?

[simonw]

I wonder if there's a GraphQL pattern for this? I want to return JSON from a query which informs how a new GraphQL query should be constructed.

I could return a string which is a fragment of GraphQL filter syntax which can be concatenated into the new query. Feels a bit gross though:

{
    "repos": {
        "facets": {
            "name": "Cleopaws",
            "filter": "{name: {eq: \"cleopaws\"}}"
        }
    }
}