sortable_columns_for_table() no longer uses inspect()

Refs #420

datasette/app.py

@@ -33,6 +33,7 @@ from .utils import (
     module_from_path,
     sqlite3,
     sqlite_timelimit,
+    table_columns,
     to_css_class
 )
 from .inspect import inspect_hash, inspect_views, inspect_tables
@@ -463,6 +464,11 @@ class Datasette:
             for p in ps
         ]
 
+    async def table_columns(self, db_name, table):
+        return await self.execute_against_connection_in_thread(
+            db_name, lambda conn: table_columns(conn, table)
+        )
+
     async def execute_against_connection_in_thread(self, db_name, fn):
         def in_thread():
             conn = getattr(connections, db_name, None)

datasette/inspect.py

@@ -5,6 +5,7 @@ from .utils import (
     detect_fts,
     escape_sqlite,
     get_all_foreign_keys,
+    table_columns,
     sqlite3
 )
 
@@ -78,12 +79,7 @@ def inspect_tables(conn, database_metadata):
             # e.g. "select count(*) from some_fts;"
             count = 0
 
-        column_names = [
-            r[1]
-            for r in conn.execute(
-                "PRAGMA table_info({});".format(escape_sqlite(table))
-            ).fetchall()
-        ]
+        column_names = table_columns(conn, table)
 
         tables[table] = {
             "name": table,

datasette/utils.py

@@ -536,6 +536,15 @@ def detect_fts_sql(table):
     '''.format(table=table)
 
 
+def table_columns(conn, table):
+    return [
+        r[1]
+        for r in conn.execute(
+            "PRAGMA table_info({});".format(escape_sqlite(table))
+        ).fetchall()
+    ]
+
+
 class Filter:
     def __init__(self, key, display, sql_template, human_template, format='{}', numeric=False, no_argument=False):
         self.key = key

datasette/views/table.py

@@ -19,6 +19,7 @@ from datasette.utils import (
     path_with_removed_args,
     path_with_replaced_args,
     sqlite3,
+    table_columns,
     to_css_class,
     urlsafe_components,
     value_as_boolean,
@@ -31,13 +32,12 @@ LINK_WITH_VALUE = '<a href="/{database}/{table}/{link_id}">{id}</a>'
 
 class RowTableShared(BaseView):
 
-    def sortable_columns_for_table(self, database, table, use_rowid):
+    async def sortable_columns_for_table(self, database, table, use_rowid):
         table_metadata = self.table_metadata(database, table)
         if "sortable_columns" in table_metadata:
             sortable_columns = set(table_metadata["sortable_columns"])
         else:
-            table_info = self.ds.inspect()[database]["tables"].get(table) or {}
-            sortable_columns = set(table_info.get("columns", []))
+            sortable_columns = set(await self.ds.table_columns(database, table))
         if use_rowid:
             sortable_columns.add("rowid")
         return sortable_columns
@@ -121,7 +121,7 @@ class RowTableShared(BaseView):
         "Returns columns, rows for specified table - including fancy foreign key treatment"
         table_metadata = self.table_metadata(database, table)
         info = self.ds.inspect()[database]
-        sortable_columns = self.sortable_columns_for_table(database, table, True)
+        sortable_columns = await self.sortable_columns_for_table(database, table, True)
         columns = [
             {"name": r[0], "sortable": r[0] in sortable_columns} for r in description
         ]
@@ -363,7 +363,7 @@ class TableView(RowTableShared):
         if not is_view:
             table_rows_count = table_info["count"]
 
-        sortable_columns = self.sortable_columns_for_table(database, table, use_rowid)
+        sortable_columns = await self.sortable_columns_for_table(database, table, use_rowid)
 
         # Allow for custom sort order
         sort = special_args.get("_sort")

tests/test_utils.py

@@ -7,6 +7,7 @@ import json
 import os
 import pytest
 from sanic.request import Request
+import sqlite3
 import tempfile
 from unittest.mock import patch
 
@@ -357,6 +358,14 @@ async def test_resolve_table_and_format(
     assert expected_format == actual_format
 
 
+def test_table_columns():
+    conn = sqlite3.connect(":memory:")
+    conn.executescript("""
+    create table places (id integer primary key, name text, bob integer)
+    """)
+    assert ["id", "name", "bob"] == utils.table_columns(conn, "places")
+
+
 @pytest.mark.parametrize(
     "path,format,extra_qs,expected",
     [