Fixed bug on rows page, added unit test

Rows page for rows that linked to the same table in more
than one columns were display incorrectly. Fixed that and added a test.

Also introduced /db/table/row-pk.json?_extras=foreign_key_tables

This is used by the new unit test, but is the first example of a new
?_extras=comma-separated-list pattern I am introducing.

datasette/app.py

@@ -685,14 +685,19 @@ class RowView(BaseView):
                 'foreign_key_tables': await self.foreign_key_tables(name, table, pk_values),
             }
 
-        return {
+        data = {
             'database': name,
             'table': table,
             'rows': rows,
             'columns': columns,
             'primary_keys': pks,
             'primary_key_values': pk_values,
-        }, template_data
+        }
+
+        if 'foreign_key_tables' in (request.raw_args.get('_extras') or '').split(','):
+            data['foreign_key_tables'] = await self.foreign_key_tables(name, table, pk_values)
+
+        return data, template_data
 
     async def foreign_key_tables(self, name, table, pk_values):
         if len(pk_values) != 1:
@@ -702,7 +707,7 @@ class RowView(BaseView):
             return []
         foreign_keys = table_info['foreign_keys']['incoming']
         sql = 'select ' + ', '.join([
-            '(select count(*) from {table} where "{column}"= :id)'.format(
+            '(select count(*) from {table} where "{column}"=:id)'.format(
                 table=escape_sqlite_table_name(fk['other_table']),
                 column=fk['other_column'],
             )
@@ -713,12 +718,16 @@ class RowView(BaseView):
         except sqlite3.OperationalError:
             # Almost certainly hit the timeout
             return []
-        foreign_table_counts = dict(zip([fk['other_table'] for fk in foreign_keys], rows[0]))
+        foreign_table_counts = dict(
+            zip(
+                [(fk['other_table'], fk['other_column']) for fk in foreign_keys],
+                list(rows[0]),
+            )
+        )
         foreign_key_tables = []
         for fk in foreign_keys:
-            count = foreign_table_counts[fk['other_table']]
-            if count:
-                foreign_key_tables.append({**fk, **{'count': count}})
+            count = foreign_table_counts.get((fk['other_table'], fk['other_column'])) or 0
+            foreign_key_tables.append({**fk, **{'count': count}})
         return foreign_key_tables
 
 

tests/test_app.py

@@ -37,7 +37,7 @@ def test_homepage(app_client):
     assert response.json.keys() == {'test_tables': 0}.keys()
     d = response.json['test_tables']
     assert d['name'] == 'test_tables'
-    assert d['tables_count'] == 6
+    assert d['tables_count'] == 7
 
 
 def test_database_page(app_client):
@@ -63,6 +63,28 @@ def test_database_page(app_client):
         'hidden': False,
         'foreign_keys': {'incoming': [], 'outgoing': []},
         'label_column': None,
+    }, {
+        'columns': ['pk', 'f1', 'f2', 'f3'],
+        'name': 'complex_foreign_keys',
+        'count': 1,
+        'foreign_keys': {
+            'incoming': [],
+            'outgoing': [{
+                'column': 'f3',
+                'other_column': 'id',
+                'other_table': 'simple_primary_key'
+            }, {
+                'column': 'f2',
+                'other_column': 'id',
+                'other_table': 'simple_primary_key'
+            }, {
+                'column': 'f1',
+                'other_column': 'id',
+                'other_table': 'simple_primary_key'
+            }],
+        },
+        'hidden': False,
+        'label_column': None,
     }, {
         'columns': ['pk1', 'pk2', 'content'],
         'name': 'compound_primary_key',
@@ -82,7 +104,22 @@ def test_database_page(app_client):
         'name': 'simple_primary_key',
         'count': 3,
         'hidden': False,
-        'foreign_keys': {'incoming': [], 'outgoing': []},
+        'foreign_keys': {
+            'incoming': [{
+                'column': 'id',
+                'other_column': 'f3',
+                'other_table': 'complex_foreign_keys'
+            }, {
+                'column': 'id',
+                'other_column': 'f2',
+                'other_table': 'complex_foreign_keys'
+            }, {
+                'column': 'id',
+                'other_column': 'f1',
+                'other_table': 'complex_foreign_keys'
+            }],
+            'outgoing': [],
+        },
         'label_column': None,
     }, {
         'columns': ['pk', 'content'],
@@ -270,6 +307,27 @@ def test_row(app_client):
     assert [{'pk': '1', 'content': 'hello'}] == response.json['rows']
 
 
+def test_row_foreign_key_tables(app_client):
+    response = app_client.get('/test_tables/simple_primary_key/1.json?_extras=foreign_key_tables', gather_request=False)
+    assert response.status == 200
+    assert [{
+        'column': 'id',
+        'count': 1,
+        'other_column': 'f3',
+        'other_table': 'complex_foreign_keys'
+    }, {
+        'column': 'id',
+        'count': 0,
+        'other_column': 'f2',
+        'other_table': 'complex_foreign_keys'
+    }, {
+        'column': 'id',
+        'count': 1,
+        'other_column': 'f1',
+        'other_table': 'complex_foreign_keys'
+    }] == response.json['foreign_key_tables']
+
+
 def test_add_filter_redirects(app_client):
     filter_args = urllib.parse.urlencode({
         '_filter_column': 'content',
@@ -379,10 +437,22 @@ CREATE TABLE "table/with/slashes.csv" (
   content text
 );
 
+CREATE TABLE "complex_foreign_keys" (
+  pk varchar(30) primary key,
+  f1 text,
+  f2 text,
+  f3 text,
+  FOREIGN KEY ("f1") REFERENCES [simple_primary_key](id),
+  FOREIGN KEY ("f2") REFERENCES [simple_primary_key](id),
+  FOREIGN KEY ("f3") REFERENCES [simple_primary_key](id)
+);
+
 INSERT INTO simple_primary_key VALUES (1, 'hello');
 INSERT INTO simple_primary_key VALUES (2, 'world');
 INSERT INTO simple_primary_key VALUES (3, '');
 
+INSERT INTO complex_foreign_keys VALUES (1, 1, 2, 1);
+
 INSERT INTO [table/with/slashes.csv] VALUES (3, 'hey');
 
 CREATE VIEW simple_view AS