Template slot family of plugin hooks - top_homepage() and others

New plugin hooks:

top_homepage
top_database
top_table
top_row
top_query
top_canned_query

New datasette.utils.make_slot_function()

Closes #1191

datasette/views/database.py

@@ -1,5 +1,4 @@
 from dataclasses import dataclass, field
-from typing import Callable
 from urllib.parse import parse_qsl, urlencode
 import asyncio
 import hashlib
@@ -18,6 +17,7 @@ from datasette.utils import (
     call_with_supported_arguments,
     derive_named_parameters,
     format_bytes,
+    make_slot_function,
     tilde_decode,
     to_css_class,
     validate_sql_select,
@@ -161,6 +161,9 @@ class DatabaseView(View):
                 f"{'*' if template_name == template.name else ''}{template_name}"
                 for template_name in templates
             ],
+            "top_database": make_slot_function(
+                "top_database", datasette, request, database=database
+            ),
         }
         return Response.html(
             await datasette.render_template(
@@ -246,6 +249,12 @@ class QueryContext:
             "help": "List of templates that were considered for rendering this page"
         }
     )
+    top_query: callable = field(
+        metadata={"help": "Callable to render the top_query slot"}
+    )
+    top_canned_query: callable = field(
+        metadata={"help": "Callable to render the top_canned_query slot"}
+    )
 
 
 async def get_tables(datasette, request, db):
@@ -727,6 +736,16 @@ class QueryView(View):
                             f"{'*' if template_name == template.name else ''}{template_name}"
                             for template_name in templates
                         ],
+                        top_query=make_slot_function(
+                            "top_query", datasette, request, database=database, sql=sql
+                        ),
+                        top_canned_query=make_slot_function(
+                            "top_canned_query",
+                            datasette,
+                            request,
+                            database=database,
+                            query_name=canned_query["name"] if canned_query else None,
+                        ),
                     ),
                     request=request,
                     view_name="database",

datasette/views/index.py

@@ -1,10 +1,12 @@
-import hashlib
 import json
 
-from datasette.utils import add_cors_headers, CustomJSONEncoder
+from datasette.plugins import pm
+from datasette.utils import add_cors_headers, make_slot_function, CustomJSONEncoder
 from datasette.utils.asgi import Response
 from datasette.version import __version__
 
+from markupsafe import Markup
+
 from .base import BaseView
 
 
@@ -142,5 +144,8 @@ class IndexView(BaseView):
                     "private": not await self.ds.permission_allowed(
                         None, "view-instance"
                     ),
+                    "top_homepage": make_slot_function(
+                        "top_homepage", self.ds, request
+                    ),
                 },
             )

datasette/views/row.py

@@ -2,11 +2,9 @@ from datasette.utils.asgi import NotFound, Forbidden, Response
 from datasette.database import QueryInterrupted
 from .base import DataView, BaseView, _error
 from datasette.utils import (
-    tilde_decode,
-    urlsafe_components,
+    make_slot_function,
     to_css_class,
     escape_sqlite,
-    row_sql_params_pks,
 )
 import json
 import sqlite_utils
@@ -73,6 +71,14 @@ class RowView(DataView):
                 .get(database, {})
                 .get("tables", {})
                 .get(table, {}),
+                "top_row": make_slot_function(
+                    "top_row",
+                    self.ds,
+                    request,
+                    database=resolved.db.name,
+                    table=resolved.table,
+                    row=rows[0],
+                ),
             }
 
         data = {

datasette/views/table.py

@@ -17,6 +17,7 @@ from datasette.utils import (
     append_querystring,
     compound_keys_after_sql,
     format_bytes,
+    make_slot_function,
     tilde_encode,
     escape_sqlite,
     filters_should_redirect,
@@ -842,6 +843,13 @@ async def table_view_traced(datasette, request):
                         f"{'*' if template_name == template.name else ''}{template_name}"
                         for template_name in templates
                     ],
+                    top_table=make_slot_function(
+                        "top_table",
+                        datasette,
+                        request,
+                        database=resolved.db.name,
+                        table=resolved.table,
+                    ),
                 ),
                 request=request,
                 view_name="table",