From f5dbe61a4568c0915ec6be820095c2960cf0857c Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Sun, 25 Oct 2020 22:06:20 -0700
Subject: [PATCH] -o now opens to most relevant page, closes #976

---
 datasette/cli.py            | 10 ++++++++--
 datasette/utils/__init__.py | 15 +++++++++++++++
 tests/test_utils.py         | 26 ++++++++++++++++++++++++--
 3 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/datasette/cli.py b/datasette/cli.py
index f0752b7c..ece03636 100644
--- a/datasette/cli.py
+++ b/datasette/cli.py
@@ -17,6 +17,7 @@ from .utils import (
     parse_metadata,
     ConnectionProblem,
     SpatialiteConnectionProblem,
+    initial_path_for_datasette,
     temporary_docker_directory,
     value_as_boolean,
     SpatialiteNotFound,
@@ -456,14 +457,19 @@ def serve(
         return
 
     # Start the server
+    url = None
     if root:
         url = "http://{}:{}{}?token={}".format(
             host, port, ds.urls.path("-/auth-token"), ds._root_token
         )
         print(url)
-    else:
-        url = "http://{}:{}{}".format(host, port, ds.urls.instance())
     if open_browser:
+        if url is None:
+            # Figure out most convenient URL - to table, database or homepage
+            path = asyncio.get_event_loop().run_until_complete(
+                initial_path_for_datasette(ds)
+            )
+            url = "http://{}:{}{}".format(host, port, path)
         webbrowser.open(url)
     uvicorn.run(
         ds.app(), host=host, port=port, log_level="info", lifespan="on", workers=1
diff --git a/datasette/utils/__init__.py b/datasette/utils/__init__.py
index dea50861..f819aa82 100644
--- a/datasette/utils/__init__.py
+++ b/datasette/utils/__init__.py
@@ -991,3 +991,18 @@ def find_spatialite():
         if os.path.exists(path):
             return path
     raise SpatialiteNotFound
+
+
+async def initial_path_for_datasette(datasette):
+    "Return suggested path for opening this Datasette, based on number of DBs and tables"
+    if len(datasette.databases) == 1:
+        db_name = next(iter(datasette.databases.keys()))
+        path = datasette.urls.database(db_name)
+        # Does this DB only have one table?
+        db = next(iter(datasette.databases.values()))
+        tables = await db.table_names()
+        if len(tables) == 1:
+            path = datasette.urls.table(db_name, tables[0])
+    else:
+        path = datasette.urls.instance()
+    return path
diff --git a/tests/test_utils.py b/tests/test_utils.py
index c244a6f4..0e2af098 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,10 +1,9 @@
 """
 Tests for various datasette helper functions.
 """
-
+from datasette.app import Datasette
 from datasette import utils
 from datasette.utils.asgi import Request
-from datasette.filters import Filters
 import json
 import os
 import pathlib
@@ -554,3 +553,26 @@ def test_resolve_env_secrets(config, expected):
 )
 def test_display_actor(actor, expected):
     assert expected == utils.display_actor(actor)
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "dbs,expected_path",
+    [
+        (["one_table"], "/one/one"),
+        (["two_tables"], "/two"),
+        (["one_table", "two_tables"], "/"),
+    ],
+)
+async def test_initial_path_for_datasette(tmp_path_factory, dbs, expected_path):
+    db_dir = tmp_path_factory.mktemp("dbs")
+    one_table = str(db_dir / "one.db")
+    sqlite3.connect(one_table).execute("create table one (id integer primary key)")
+    two_tables = str(db_dir / "two.db")
+    sqlite3.connect(two_tables).execute("create table two (id integer primary key)")
+    sqlite3.connect(two_tables).execute("create table three (id integer primary key)")
+    datasette = Datasette(
+        [{"one_table": one_table, "two_tables": two_tables}[db] for db in dbs]
+    )
+    path = await utils.initial_path_for_datasette(datasette)
+    assert path == expected_path