New truncate_cells_html config for truncating cells, closes #330

datasette/app.py

@@ -101,6 +101,9 @@ CONFIG_OPTIONS = (
     ConfigOption("max_csv_mb", 100, """
         Maximum size allowed for CSV export in MB. Set 0 to disable this limit.
     """.strip()),
+    ConfigOption("truncate_cells_html", 2048, """
+        Truncate cells longer than this in HTML table view. Set to 0 to disable.
+    """.strip()),
 )
 DEFAULT_CONFIG = {
     option.name: option.default

datasette/views/table.py

@@ -117,6 +117,7 @@ class RowTableShared(BaseView):
         description,
         rows,
         link_column=False,
+        truncate_cells=0,
     ):
         "Returns columns, rows for specified table - including fancy foreign key treatment"
         table_metadata = self.table_metadata(database, table)
@@ -202,6 +203,8 @@ class RowTableShared(BaseView):
                     )
                 else:
                     display_value = str(value)
+                    if truncate_cells and len(display_value) > truncate_cells:
+                        display_value = display_value[:truncate_cells] + u"\u2026"
 
                 cells.append({"column": column, "value": display_value})
             cell_rows.append(cells)
@@ -723,6 +726,7 @@ class TableView(RowTableShared):
                 results.description,
                 rows,
                 link_column=not is_view,
+                truncate_cells=self.ds.config["truncate_cells_html"],
             )
             metadata = self.ds.metadata.get("databases", {}).get(name, {}).get(
                 "tables", {}
@@ -827,6 +831,7 @@ class RowView(RowTableShared):
                 results.description,
                 rows,
                 link_column=False,
+                truncate_cells=0,
             )
             for column in display_columns:
                 column["sortable"] = False

docs/config.rst

@@ -152,3 +152,14 @@ You can disable the limit entirely by settings this to 0:
 ::
 
     datasette mydatabase.db --config max_csv_mb:0
+
+.. _config_truncate_cells_html:
+
+truncate_cells_html
+-------------------
+
+In the HTML table view, truncate any strings that are longer than this value. The full value will still be available in CSV, JSON and on the individual row HTML page. Set this to 0 to disable truncation.
+
+::
+
+    datasette mydatabase.db --config truncate_cells_html:0

tests/test_api.py

@@ -974,6 +974,7 @@ def test_config_json(app_client):
         "cache_size_kb": 0,
         "allow_csv_stream": True,
         "max_csv_mb": 100,
+        "truncate_cells_html": 2048,
     } == response.json
 
 

tests/test_html.py

@@ -69,6 +69,40 @@ def test_row_strange_table_name(app_client):
     assert response.status == 200
 
 
+def test_table_cell_truncation():
+    for client in app_client(config={
+        "truncate_cells_html": 5,
+    }):
+        response = client.get("/fixtures/facetable")
+        assert response.status == 200
+        table = Soup(response.body, "html.parser").find("table")
+        assert table["class"] == ["rows-and-columns"]
+        assert [
+            "Missi…", "Dogpa…", "SOMA", "Tende…", "Berna…", "Hayes…",
+            "Holly…", "Downt…", "Los F…", "Korea…", "Downt…", "Greek…",
+            "Corkt…", "Mexic…", "Arcad…"
+        ] == [
+            td.string for td in table.findAll("td", {
+                "class": "col-neighborhood"
+            })
+        ]
+
+
+def test_row_page_does_not_truncate():
+    for client in app_client(config={
+        "truncate_cells_html": 5,
+    }):
+        response = client.get("/fixtures/facetable/1")
+        assert response.status == 200
+        table = Soup(response.body, "html.parser").find("table")
+        assert table["class"] == ["rows-and-columns"]
+        assert ["Mission"] == [
+            td.string for td in table.findAll("td", {
+                "class": "col-neighborhood"
+            })
+        ]
+
+
 def test_add_filter_redirects(app_client):
     filter_args = urllib.parse.urlencode({
         '_filter_column': 'content',