Don't show 'None' as label for nullable foreign key, closes #406

datasette/views/table.py

@@ -637,7 +637,7 @@ class TableView(RowTableShared):
                     new_row = CustomRow(columns)
                     for column in row.keys():
                         value = row[column]
-                        if (column, value) in expanded_labels:
+                        if (column, value) in expanded_labels and value is not None:
                             new_row[column] = {
                                 "value": value,
                                 "label": expanded_labels[(column, value)],

tests/fixtures.py

@@ -754,6 +754,7 @@ INSERT INTO primary_key_multiple_columns VALUES (1, 'hey', 'world');
 INSERT INTO primary_key_multiple_columns_explicit_label VALUES (1, 'hey', 'world2');
 
 INSERT INTO foreign_key_references VALUES (1, 1, 1);
+INSERT INTO foreign_key_references VALUES (2, null, null);
 
 INSERT INTO complex_foreign_keys VALUES (1, 1, 2, 1);
 INSERT INTO custom_foreign_key_label VALUES (1, 1);

tests/test_api.py

@@ -216,7 +216,7 @@ def test_database_page(app_client):
             "name": "foreign_key_references",
             "columns": ["pk", "foreign_key_with_label", "foreign_key_with_no_label"],
             "primary_keys": ["pk"],
-            "count": 1,
+            "count": 2,
             "hidden": False,
             "fts_table": None,
             "foreign_keys": {
@@ -1519,7 +1519,7 @@ def test_expand_labels(app_client):
 def test_expand_label(app_client):
     response = app_client.get(
         "/fixtures/foreign_key_references.json?_shape=object"
-        "&_label=foreign_key_with_label"
+        "&_label=foreign_key_with_label&_size=1"
     )
     assert {
         "1": {
@@ -1693,3 +1693,17 @@ def test_common_prefix_database_names(app_client_conflicting_database_names):
             app_client_conflicting_database_names.get(path).body.decode("utf8")
         )
         assert db_name == data["database"]
+
+
+def test_null_foreign_keys_are_not_expanded(app_client):
+    response = app_client.get(
+        "/fixtures/foreign_key_references.json?_shape=array&_labels=on"
+    )
+    assert [
+        {
+            "pk": "1",
+            "foreign_key_with_label": {"value": "1", "label": "hello"},
+            "foreign_key_with_no_label": {"value": "1", "label": "1"},
+        },
+        {"pk": "2", "foreign_key_with_label": None, "foreign_key_with_no_label": None,},
+    ] == response.json

tests/test_html.py

@@ -603,7 +603,12 @@ def test_table_html_foreign_key_links(app_client):
             '<td class="col-pk"><a href="/fixtures/foreign_key_references/1">1</a></td>',
             '<td class="col-foreign_key_with_label"><a href="/fixtures/simple_primary_key/1">hello</a>\xa0<em>1</em></td>',
             '<td class="col-foreign_key_with_no_label"><a href="/fixtures/primary_key_multiple_columns/1">1</a></td>',
-        ]
+        ],
+        [
+            '<td class="col-pk"><a href="/fixtures/foreign_key_references/2">2</a></td>',
+            '<td class="col-foreign_key_with_label">\xa0</td>',
+            '<td class="col-foreign_key_with_no_label">\xa0</td>',
+        ],
     ]
     assert expected == [
         [str(td) for td in tr.select("td")] for tr in table.select("tbody tr")
@@ -611,7 +616,7 @@ def test_table_html_foreign_key_links(app_client):
 
 
 def test_table_html_disable_foreign_key_links_with_labels(app_client):
-    response = app_client.get("/fixtures/foreign_key_references?_labels=off")
+    response = app_client.get("/fixtures/foreign_key_references?_labels=off&_size=1")
     assert response.status == 200
     table = Soup(response.body, "html.parser").find("table")
     expected = [