WIP: Plugin includes

datasette/app.py

@@ -46,6 +46,7 @@
 
 from .utils import (
     PrefixedUrlString,
+    PrependingLoader,
     StartupError,
     async_call_with_supported_arguments,
     await_me_maybe,
@@ -309,7 +310,9 @@ def __init__(
             ]
         )
         self.jinja_env = Environment(
-            loader=template_loader, autoescape=True, enable_async=True
+            loader=PrependingLoader(template_loader, "_macros.html"),
+            autoescape=True,
+            enable_async=True,
         )
         self.jinja_env.filters["escape_css_string"] = escape_css_string
         self.jinja_env.filters["quote_plus"] = lambda u: urllib.parse.quote_plus(u)
@@ -759,6 +762,14 @@ def _register_renderers(self):
                 renderer.get("can_render") or (lambda: True),
             )
 
+    def _include_templates(self, name, **kwargs):
+        include_templates = []
+        for templates in getattr(pm.hook, name)(**kwargs):
+            if isinstance(templates, str):
+                templates = [templates]
+            include_templates.extend(templates)
+        return include_templates
+
     async def render_template(
         self, templates, context=None, request=None, view_name=None
     ):

datasette/templates/table.html

@@ -51,6 +51,8 @@ <h1>{{ metadata.title or table }}{% if is_view %} (view){% endif %}{% if private
 
 {% block description_source_license %}{% include "_description_source_license.html" %}{% endblock %}
 
+{{ includes("table-top-includes", table_top_includes) }}
+
 {% if filtered_table_rows_count or human_description_en %}
     <h3>{% if filtered_table_rows_count or filtered_table_rows_count == 0 %}{{ "{:,}".format(filtered_table_rows_count) }} row{% if filtered_table_rows_count == 1 %}{% else %}s{% endif %}{% endif %}
         {% if human_description_en %}{{ human_description_en }}{% endif %}
@@ -201,6 +203,8 @@ <h3>Advanced export</h3>
     </div>
 {% endif %}
 
+{{ includes("table-bottom-includes", table_bottom_includes) }}
+
 {% if table_definition %}
     <pre class="wrapped-sql">{{ table_definition }}</pre>
 {% endif %}

datasette/utils/__init__.py

@@ -18,6 +18,7 @@
 import urllib
 import numbers
 import yaml
+from jinja2 import BaseLoader
 from .shutil_backport import copytree
 from .sqlite import sqlite3, sqlite_version, supports_table_xinfo
 from ..plugins import pm
@@ -1068,3 +1069,26 @@ def method(self, *args, **kwargs):
 
 class StartupError(Exception):
     pass
+
+
+class PrependingLoader(BaseLoader):
+    # Based on http://codyaray.com/2015/05/auto-load-jinja2-macros
+    def __init__(self, delegate, prepend_template):
+        self.delegate = delegate
+        self.prepend_template = prepend_template
+
+    def get_source(self, environment, template):
+        prepend_source, _, prepend_uptodate = self.delegate.get_source(
+            environment, self.prepend_template
+        )
+        main_source, main_filename, main_uptodate = self.delegate.get_source(
+            environment, template
+        )
+        uptodate = lambda: prepend_uptodate() and main_uptodate()
+        return prepend_source + main_source, main_filename, uptodate
+
+    def list_templates(self):
+        return self.delegate.list_templates()
+
+    def select_template(self, *args, **kwargs):
+        return self.delegate.select_template(*args, **kwargs)

datasette/views/table.py

@@ -880,6 +880,20 @@ async def table_actions():
                 "metadata": metadata,
                 "view_definition": await db.get_view_definition(table),
                 "table_definition": await db.get_table_definition(table),
+                "table_top_includes": self.ds._include_templates(
+                    "include_table_top",
+                    database=database,
+                    table=table,
+                    actor=request.actor,
+                    datasette=self.ds,
+                ),
+                "table_bottom_includes": self.ds._include_templates(
+                    "include_table_bottom",
+                    database=database,
+                    table=table,
+                    actor=request.actor,
+                    datasette=self.ds,
+                ),
             }
 
         return (