New sortable_columns option in metadata.json to control sort options

You can now explicitly set which columns in a table can be used for sorting
using the _sort and _sort_desc arguments using metadata.json:

    {
        "databases": {
            "database1": {
                "tables": {
                    "example_table": {
                        "sortable_columns": [
                            "height",
                            "weight"
                        ]
                    }
                }
            }
        }
    }

Refs #189

datasette/app.py

@@ -456,10 +456,27 @@ async def view_get(self, request, name, hash, **kwargs):
 
 
 class RowTableShared(BaseView):
+    def sortable_columns_for_table(self, name, table, use_rowid):
+        table_metadata = self.ds.metadata.get(
+            'databases', {}
+        ).get(name, {}).get('tables', {}).get(table, {})
+        if 'sortable_columns' in table_metadata:
+            sortable_columns = set(table_metadata['sortable_columns'])
+        else:
+            table_info = self.ds.inspect()[name]['tables'].get(table) or {}
+            sortable_columns = set(table_info.get('columns', []))
+        if use_rowid:
+            sortable_columns.add('rowid')
+        return sortable_columns
+
     async def display_columns_and_rows(self, database, table, description, rows, link_column=False, expand_foreign_keys=True):
         "Returns columns, rows for specified table - including fancy foreign key treatment"
         info = self.ds.inspect()[database]
-        columns = [r[0] for r in description]
+        sortable_columns = self.sortable_columns_for_table(database, table, True)
+        columns = [{
+            'name': r[0],
+            'sortable': r[0] in sortable_columns,
+        } for r in description]
         tables = info['tables']
         table_info = tables.get(table) or {}
         pks = await self.pks_for_table(database, table)
@@ -505,7 +522,8 @@ async def display_columns_and_rows(self, database, table, description, rows, lin
                         )
                     ),
                 })
-            for value, column in zip(row, columns):
+            for value, column_dict in zip(row, columns):
+                column = column_dict['name']
                 if (column, value) in expanded:
                     other_table, label = expanded[(column, value)]
                     display_value = jinja2.Markup(
@@ -533,7 +551,10 @@ async def display_columns_and_rows(self, database, table, description, rows, lin
             cell_rows.append(cells)
 
         if link_column:
-            columns = ['Link'] + columns
+            columns = [{
+                'name': 'Link',
+                'sortable': False,
+            }] + columns
         return columns, cell_rows
 
 
@@ -623,7 +644,7 @@ async def data(self, request, name, hash, table):
         if not is_view:
             table_info = info[name]['tables'][table]
             table_rows = table_info['count']
-            sortable_columns = set(table_info['columns'])
+            sortable_columns = self.sortable_columns_for_table(name, table, use_rowid)
 
         # Allow for custom sort order
         sort = special_args.get('_sort')
@@ -885,6 +906,8 @@ async def template_data():
             display_columns, display_rows = await self.display_columns_and_rows(
                 name, table, description, rows, link_column=False, expand_foreign_keys=True
             )
+            for column in display_columns:
+                column['sortable'] = False
             return {
                 'database_hash': hash,
                 'foreign_key_tables': await self.foreign_key_tables(name, table, pk_values),
@@ -895,7 +918,6 @@ async def template_data():
                     '_rows_and_columns-row-{}-{}.html'.format(to_css_class(name), to_css_class(table)),
                     '_rows_and_columns.html',
                 ],
-                'disable_sort': True,
                 'enumerate': enumerate,
                 'metadata': self.ds.metadata.get(
                     'databases', {}

datasette/templates/_rows_and_columns.html

@@ -1,15 +1,15 @@
 <table>
     <thead>
         <tr>
-            {% for i, column in enumerate(display_columns) %}
+            {% for column in display_columns %}
                 <th scope="col">
-                    {% if i == 0 or disable_sort %}
-                        {{ column }}
+                    {% if not column.sortable %}
+                        {{ column.name }}
                     {% else %}
-                        {% if column == sort %}
-                            <a href="{{ path_with_added_args(request, {'_sort_desc': column, '_sort': None, '_next': None}) }}" rel="nofollow">{{ column }}&nbsp;▼</a>
+                        {% if column.name == sort %}
+                            <a href="{{ path_with_added_args(request, {'_sort_desc': column.name, '_sort': None, '_next': None}) }}" rel="nofollow">{{ column.name }}&nbsp;▼</a>
                         {% else %}
-                            <a href="{{ path_with_added_args(request, {'_sort': column, '_sort_desc': None, '_next': None}) }}" rel="nofollow">{{ column }}{% if column == sort_desc %}&nbsp;▲{% endif %}</a>
+                            <a href="{{ path_with_added_args(request, {'_sort': column.name, '_sort_desc': None, '_next': None}) }}" rel="nofollow">{{ column.name }}{% if column.name == sort_desc %}&nbsp;▲{% endif %}</a>
                         {% endif %}
                     {% endif %}
                 </th>

datasette/templates/table.html

@@ -8,7 +8,7 @@
 <style>
 @media only screen and (max-width: 576px) {
 {% for column in display_columns %}
-    td:nth-of-type({{ loop.index }}):before { content: "{{ column|escape_css_string }}"; }
+    td:nth-of-type({{ loop.index }}):before { content: "{{ column.name|escape_css_string }}"; }
 {% endfor %}
 }
 </style>

docs/metadata.rst

@@ -55,6 +55,33 @@ You can also provide metadata at the per-database or per-table level, like this:
 
 Each of the top-level metadata fields can be used at the database and table level.
 
+Setting which columns can be used for sorting
+---------------------------------------------
+
+Datasette allows any column to be used for sorting by default. If you need to
+control which columns are available for sorting you can do so using the optional
+``sortable_columns`` key::
+
+    {
+        "databases": {
+            "database1": {
+                "tables": {
+                    "example_table": {
+                        "sortable_columns": [
+                            "height",
+                            "weight"
+                        ]
+                    }
+                }
+            }
+        }
+    }
+
+This will restrict sorting of ``example_table`` to just the ``height`` and
+``weight`` columns.
+
+You can also disable sorting entirely by setting ``"sortable_columns": []``
+
 Generating a metadata skeleton
 ------------------------------
 

tests/fixtures.py

@@ -68,9 +68,19 @@ def generate_sortable_rows(num):
                 'simple_primary_key': {
                     'description_html': 'Simple <em>primary</em> key',
                     'title': 'This <em>HTML</em> is escaped',
-                }
+                },
+                'sortable': {
+                    'sortable_columns': [
+                        'sortable',
+                        'sortable_with_nulls',
+                        'sortable_with_nulls_2',
+                    ]
+                },
+                'no_primary_key': {
+                    'sortable_columns': [],
+                },
             }
-        }
+        },
     }
 }
 

tests/test_api.py

@@ -412,12 +412,27 @@ def test_sortable_argument_errors(app_client):
     )
     assert 'Cannot sort table by badcolumn2' == response.json['error']
     response = app_client.get(
-        '/test_tables/sortable.json?_sort=content&_sort_desc=pk2',
+        '/test_tables/sortable.json?_sort=sortable_with_nulls&_sort_desc=sortable',
         gather_request=False
     )
     assert 'Cannot use _sort and _sort_desc at the same time' == response.json['error']
 
 
+def test_sortable_columns_metadata(app_client):
+    response = app_client.get(
+        '/test_tables/sortable.json?_sort=content',
+        gather_request=False
+    )
+    assert 'Cannot sort table by content' == response.json['error']
+    # no_primary_key has ALL sort options disabled
+    for column in ('content', 'a', 'b', 'c'):
+        response = app_client.get(
+            '/test_tables/sortable.json?_sort={}'.format(column),
+            gather_request=False
+        )
+        assert 'Cannot sort table by {}'.format(column) == response.json['error']
+
+
 @pytest.mark.parametrize('path,expected_rows', [
     ('/test_tables/simple_primary_key.json?content=hello', [
         ['1', 'hello'],

tests/test_html.py

@@ -200,14 +200,10 @@ def test_row_html_simple_primary_key(app_client):
 def test_table_html_no_primary_key(app_client):
     response = app_client.get('/test_tables/no_primary_key', gather_request=False)
     table = Soup(response.body, 'html.parser').find('table')
-    ths = table.findAll('th')
-    assert 'Link' == ths[0].string.strip()
-    for expected_col, th in zip(('rowid', 'content', 'a', 'b', 'c'), ths[1:]):
-        a = th.find('a')
-        assert expected_col == a.string
-        assert a['href'].endswith('/no_primary_key?_sort={}'.format(
-            expected_col
-        ))
+    # We have disabled sorting for this table using metadata.json
+    assert [
+        'content', 'a', 'b', 'c'
+    ] == [th.string.strip() for th in table.select('thead th')[2:]]
     expected = [
         [
             '<td><a href="/test_tables/no_primary_key/{}">{}</a></td>'.format(i, i),