?_col=/?_nocol= to show/hide columns on the table page

Closes #615

* Cog icon for hiding columns
* Show all columns cog menu item
* Do not allow hide column on primary keys
* Allow both ?_col= and ?_nocol=
* De-duplicate if ?_col= passed multiple times
* 400 error if user tries to ?_nocol= a primary key
* Documentation for ?_col= and ?_nocol=

datasette/static/table.js

@@ -4,6 +4,8 @@ var DROPDOWN_HTML = `<div class="dropdown-menu">
   <li><a class="dropdown-sort-asc" href="#">Sort ascending</a></li>
   <li><a class="dropdown-sort-desc" href="#">Sort descending</a></li>
   <li><a class="dropdown-facet" href="#">Facet by this</a></li>
+  <li><a class="dropdown-hide-column" href="#">Hide this column</a></li>
+  <li><a class="dropdown-show-all-columns" href="#">Show all columns</a></li>
   <li><a class="dropdown-not-blank" href="#">Show not-blank rows</a></li>
 </ul>
 <p class="dropdown-column-type"></p>
@@ -24,7 +26,7 @@ var DROPDOWN_ICON_SVG = `<svg xmlns="http://www.w3.org/2000/svg" width="14" heig
   }
   function paramsToUrl(params) {
     var s = params.toString();
-    return s ? "?" + s : "";
+    return s ? "?" + s : location.pathname;
   }
   function sortDescUrl(column) {
     var params = getParams();
@@ -45,6 +47,16 @@ var DROPDOWN_ICON_SVG = `<svg xmlns="http://www.w3.org/2000/svg" width="14" heig
     params.append("_facet", column);
     return paramsToUrl(params);
   }
+  function hideColumnUrl(column) {
+    var params = getParams();
+    params.append("_nocol", column);
+    return paramsToUrl(params);
+  }
+  function showAllColumnsUrl() {
+    var params = getParams();
+    params.delete("_nocol");
+    return paramsToUrl(params);
+  }
   function notBlankUrl(column) {
     var params = getParams();
     params.set(`${column}__notblank`, "1");
@@ -87,18 +99,33 @@ var DROPDOWN_ICON_SVG = `<svg xmlns="http://www.w3.org/2000/svg" width="14" heig
     var sortDesc = menu.querySelector("a.dropdown-sort-desc");
     var facetItem = menu.querySelector("a.dropdown-facet");
     var notBlank = menu.querySelector("a.dropdown-not-blank");
+    var hideColumn = menu.querySelector("a.dropdown-hide-column");
+    var showAllColumns = menu.querySelector("a.dropdown-show-all-columns");
     if (params.get("_sort") == column) {
-      sort.style.display = "none";
+      sort.parentNode.style.display = "none";
     } else {
-      sort.style.display = "block";
+      sort.parentNode.style.display = "block";
       sort.setAttribute("href", sortAscUrl(column));
     }
     if (params.get("_sort_desc") == column) {
-      sortDesc.style.display = "none";
+      sortDesc.parentNode.style.display = "none";
     } else {
-      sortDesc.style.display = "block";
+      sortDesc.parentNode.style.display = "block";
       sortDesc.setAttribute("href", sortDescUrl(column));
     }
+    /* Show hide columns options */
+    if (params.get("_nocol")) {
+      showAllColumns.parentNode.style.display = "block";
+      showAllColumns.setAttribute("href", showAllColumnsUrl());
+    } else {
+      showAllColumns.parentNode.style.display = "none";
+    }
+    if (th.getAttribute("data-is-pk") != "1") {
+      hideColumn.parentNode.style.display = "block";
+      hideColumn.setAttribute("href", hideColumnUrl(column));
+    } else {
+      hideColumn.parentNode.style.display = "none";
+    }
     /* Only show facet if it's not the first column, not selected, not a single PK */
     var isFirstColumn =
       th.parentElement.querySelector("th:first-of-type") == th;
@@ -110,9 +137,9 @@ var DROPDOWN_ICON_SVG = `<svg xmlns="http://www.w3.org/2000/svg" width="14" heig
       params.getAll("_facet").includes(column) ||
       isSinglePk
     ) {
-      facetItem.style.display = "none";
+      facetItem.parentNode.style.display = "none";
     } else {
-      facetItem.style.display = "block";
+      facetItem.parentNode.style.display = "block";
       facetItem.setAttribute("href", facetUrl(column));
     }
     /* Show notBlank option if not selected AND at least one visible blank value */
@@ -123,10 +150,10 @@ var DROPDOWN_ICON_SVG = `<svg xmlns="http://www.w3.org/2000/svg" width="14" heig
       params.get(`${column}__notblank`) != "1" &&
       tdsForThisColumn.filter((el) => el.innerText.trim() == "").length
     ) {
-      notBlank.style.display = "block";
+      notBlank.parentNode.style.display = "block";
       notBlank.setAttribute("href", notBlankUrl(column));
     } else {
-      notBlank.style.display = "none";
+      notBlank.parentNode.style.display = "none";
     }
     var columnTypeP = menu.querySelector(".dropdown-column-type");
     var columnType = th.dataset.columnType;

datasette/views/table.py

@@ -64,6 +64,41 @@ class Row:
 
 
 class RowTableShared(DataView):
+    async def columns_to_select(self, db, table, request):
+        table_columns = await db.table_columns(table)
+        pks = await db.primary_keys(table)
+        columns = list(table_columns)
+        if "_col" in request.args:
+            columns = list(pks)
+            _cols = request.args.getlist("_col")
+            bad_columns = [column for column in _cols if column not in table_columns]
+            if bad_columns:
+                raise DatasetteError(
+                    "_col={} - invalid columns".format(", ".join(bad_columns)),
+                    status=400,
+                )
+            # De-duplicate maintaining order:
+            columns.extend(dict.fromkeys(_cols))
+        if "_nocol" in request.args:
+            # Return all columns EXCEPT these
+            bad_columns = [
+                column
+                for column in request.args.getlist("_nocol")
+                if (column not in table_columns) or (column in pks)
+            ]
+            if bad_columns:
+                raise DatasetteError(
+                    "_nocol={} - invalid columns".format(", ".join(bad_columns)),
+                    status=400,
+                )
+            tmp_columns = [
+                column
+                for column in columns
+                if column not in request.args.getlist("_nocol")
+            ]
+            columns = tmp_columns
+        return columns
+
     async def sortable_columns_for_table(self, database, table, use_rowid):
         db = self.ds.databases[database]
         table_metadata = self.ds.table_metadata(database, table)
@@ -323,18 +358,16 @@ class TableView(RowTableShared):
         )
 
         pks = await db.primary_keys(table)
-        table_column_details = await db.table_column_details(table)
+        table_columns = await self.columns_to_select(db, table, request)
-        table_columns = [column.name for column in table_column_details]
+        select_clause = ", ".join(escape_sqlite(t) for t in table_columns)
-
-        select_columns = ", ".join(escape_sqlite(t) for t in table_columns)
 
         use_rowid = not pks and not is_view
         if use_rowid:
-            select = f"rowid, {select_columns}"
+            select = f"rowid, {select_clause}"
             order_by = "rowid"
             order_by_pks = "rowid"
         else:
-            select = select_columns
+            select = select_clause
             order_by_pks = ", ".join([escape_sqlite(pk) for pk in pks])
             order_by = order_by_pks
 
@@ -717,6 +750,8 @@ class TableView(RowTableShared):
                 column = fk["column"]
                 if column not in columns_to_expand:
                     continue
+                if column not in columns:
+                    continue
                 expanded_columns.append(column)
                 # Gather the values
                 column_index = columns.index(column)

docs/json_api.rst

@@ -296,6 +296,12 @@ You can filter the data returned by the table based on column values using a que
 Special table arguments
 ~~~~~~~~~~~~~~~~~~~~~~~
 
+``?_col=COLUMN1&_col=COLUMN2``
+    List specific columns to display. These will be shown along with any primary keys.
+
+``?_nocol=COLUMN1&_nocol=COLUMN2``
+    List specific columns to hide - any column not listed will be displayed. Primary keys cannot be hidden.
+
 ``?_labels=on/off``
     Expand foreign key references for every possible column. See below.
 

tests/test_api.py

@@ -2009,3 +2009,62 @@ def test_http_options_request(app_client):
     response = app_client.request("/fixtures", method="OPTIONS")
     assert response.status == 200
     assert response.text == "ok"
+
+
+@pytest.mark.parametrize(
+    "path,expected_columns",
+    (
+        ("/fixtures/facetable.json?_col=created", ["pk", "created"]),
+        (
+            "/fixtures/facetable.json?_nocol=created",
+            [
+                "pk",
+                "planet_int",
+                "on_earth",
+                "state",
+                "city_id",
+                "neighborhood",
+                "tags",
+                "complex_array",
+                "distinct_some_null",
+            ],
+        ),
+        (
+            "/fixtures/facetable.json?_col=state&_col=created",
+            ["pk", "state", "created"],
+        ),
+        (
+            "/fixtures/facetable.json?_col=state&_col=state",
+            ["pk", "state"],
+        ),
+        (
+            "/fixtures/facetable.json?_col=state&_col=created&_nocol=created",
+            ["pk", "state"],
+        ),
+        (
+            "/fixtures/simple_view.json?_nocol=content",
+            ["upper_content"],
+        ),
+        ("/fixtures/simple_view.json?_col=content", ["content"]),
+    ),
+)
+def test_col_nocol(app_client, path, expected_columns):
+    response = app_client.get(path)
+    assert response.status == 200
+    columns = response.json["columns"]
+    assert columns == expected_columns
+
+
+@pytest.mark.parametrize(
+    "path,expected_error",
+    (
+        ("/fixtures/facetable.json?_col=bad", "_col=bad - invalid columns"),
+        ("/fixtures/facetable.json?_nocol=bad", "_nocol=bad - invalid columns"),
+        ("/fixtures/facetable.json?_nocol=pk", "_nocol=pk - invalid columns"),
+        ("/fixtures/simple_view.json?_col=bad", "_col=bad - invalid columns"),
+    ),
+)
+def test_col_nocol_errors(app_client, path, expected_error):
+    response = app_client.get(path)
+    assert response.status == 400
+    assert response.json["error"] == expected_error