register_output_renderer can now return Response, closes #953

datasette/views/base.py

@@ -455,13 +455,17 @@ class DataView(BaseView):
                 result = await result
             if result is None:
                 raise NotFound("No data")
-
-            r = Response(
-                body=result.get("body"),
-                status=result.get("status_code", 200),
-                content_type=result.get("content_type", "text/plain"),
-                headers=result.get("headers"),
-            )
+            if isinstance(result, dict):
+                r = Response(
+                    body=result.get("body"),
+                    status=result.get("status_code", 200),
+                    content_type=result.get("content_type", "text/plain"),
+                    headers=result.get("headers"),
+                )
+            elif isinstance(result, Response):
+                r = result
+            else:
+                assert False, "{} should be dict or Response".format(result)
         else:
             extras = {}
             if callable(extra_template_data):

docs/plugin_hooks.rst

@@ -455,7 +455,9 @@ When a request is received, the ``"render"`` callback function is called with ze
 ``view_name`` - string
     The name of the current view being called. ``index``, ``database``, ``table``, and ``row`` are the most important ones.
 
-The callback function can return ``None``, if it is unable to render the data, or a dictionary with the following keys:
+The callback function can return ``None``, if it is unable to render the data, or a :ref:`internals_response` that will be returned to the caller.
+
+It can also return a dictionary with the following keys. This format is **deprecated** as-of Datasette 0.49 and will be removed by Datasette 1.0.
 
 ``body`` - string or bytes, optional
     The response body, default empty
@@ -474,9 +476,7 @@ A simple example of an output renderer callback function:
 .. code-block:: python
 
     def render_demo():
-        return {
-            "body": "Hello World"
-        }
+        return Response.text("Hello World")
 
 Here is a more complex example:
 
@@ -490,11 +490,11 @@ Here is a more complex example:
         lines.append("=" * len(first_row))
         for row in rows:
             lines.append(" | ".join(row))
-        return {
-            "body": "\n".join(lines),
-            "content_type": "text/plain; charset=utf-8",
-            "headers": {"x-sqlite-version": result.first()[0]},
-        }
+        return Response(
+            "\n".join(lines),
+            content_type="text/plain; charset=utf-8",
+            headers={"x-sqlite-version": result.first()[0]}
+        )
 
 And here is an example ``can_render`` function which returns ``True`` only if the query results contain the columns ``atom_id``, ``atom_title`` and ``atom_updated``:
 

tests/plugins/register_output_renderer.py

@@ -1,4 +1,5 @@
 from datasette import hookimpl
+from datasette.utils.asgi import Response
 import json
 
 
@@ -56,6 +57,12 @@ def render_test_no_parameters():
     return {"body": "Hello"}
 
 
+async def render_response(request):
+    if request.args.get("_broken"):
+        return "this should break"
+    return Response.json({"this_is": "json"})
+
+
 @hookimpl
 def register_output_renderer(datasette):
     return [
@@ -65,4 +72,5 @@ def register_output_renderer(datasette):
             "can_render": can_render,
         },
         {"extension": "testnone", "callback": render_test_no_parameters},
+        {"extension": "testresponse", "render": render_response},
     ]

tests/test_html.py

@@ -559,6 +559,7 @@ def test_table_csv_json_export_interface(app_client):
         "simple_primary_key.json?id__gt=2",
         "simple_primary_key.testall?id__gt=2",
         "simple_primary_key.testnone?id__gt=2",
+        "simple_primary_key.testresponse?id__gt=2",
         "simple_primary_key.csv?id__gt=2&_size=max",
         "#export",
     ]
@@ -597,6 +598,7 @@ def test_csv_json_export_links_include_labels_if_foreign_keys(app_client):
         "facetable.json?_labels=on",
         "facetable.testall?_labels=on",
         "facetable.testnone?_labels=on",
+        "facetable.testresponse?_labels=on",
         "facetable.csv?_labels=on&_size=max",
         "#export",
     ]

tests/test_plugins.py

@@ -479,6 +479,18 @@ def test_hook_register_output_renderer_custom_headers(app_client):
     assert "2" == response.headers["x-gosh"]
 
 
+def test_hook_register_output_renderer_returning_response(app_client):
+    response = app_client.get("/fixtures/facetable.testresponse")
+    assert 200 == response.status
+    assert response.json == {"this_is": "json"}
+
+
+def test_hook_register_output_renderer_returning_broken_value(app_client):
+    response = app_client.get("/fixtures/facetable.testresponse?_broken=1")
+    assert 500 == response.status
+    assert "this should break should be dict or Response" in response.text
+
+
 def test_hook_register_output_renderer_can_render(app_client):
     response = app_client.get("/fixtures/facetable?_no_can_render=1")
     assert response.status == 200