Handle ETS tables with mixed number of columns (#21)

* Handle ETS tables with mixed number of columns * Update lib/kino/ets.ex Co-authored-by: José Valim <[email protected]> Co-authored-by: José Valim <[email protected]>
livebook-dev · Jun 21, 2021 · ed0ae42 · ed0ae42
1 parent f8cacc2
commit ed0ae42
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Showing 2 changed files with 33 additions and 8 deletions.
diff --git a/lib/kino/ets.ex b/lib/kino/ets.ex
@@ -73,7 +73,7 @@ defmodule Kino.ETS do
 
     columns =
       case :ets.match_object(state.tid, :_, 1) do
-        {[record], _} -> columns_structure_from_record(record)
+        {[record], _} -> columns_structure_for_records([record])
         :"$end_of_table" -> []
       end
 
@@ -94,7 +94,7 @@ defmodule Kino.ETS do
     columns =
       case records do
         [] -> :initial
-        [record | _] -> columns_structure_from_record(record)
+        records -> columns_structure_for_records(records)
       end
 
     send(pid, {:rows, %{rows: rows, total_rows: total_rows, columns: columns}})
@@ -106,13 +106,15 @@ defmodule Kino.ETS do
     {:stop, :shutdown, state}
   end
 
-  defp columns_structure_from_record(record) do
-    record
-    |> Tuple.to_list()
-    |> Enum.with_index()
-    |> Enum.map(fn {_, idx} ->
+  defp columns_structure_for_records(records) do
+    max_columns =
+      records
+      |> Enum.map(&tuple_size/1)
+      |> Enum.max()
+
+    for idx <- 0..(max_columns - 1) do
       %{key: idx, label: "#{idx + 1}"}
-    end)
+    end
   end
 
   defp get_records(tid, rows_spec) do

diff --git a/test/kino/ets_test.exs b/test/kino/ets_test.exs
@@ -134,6 +134,29 @@ defmodule Kino.ETSTest do
                         columns: [_, _]
                       }}
     end
+
+    test "determines enough columns to accommodate longest record", %{tid: tid} do
+      :ets.insert(tid, {4, "Sherlock Holmes", 100})
+      :ets.insert(tid, {5, "John Watson", 150, :doctor})
+      :ets.insert(tid, {6})
+
+      widget = Kino.ETS.start(tid)
+      connect_self(widget)
+
+      spec = %{
+        offset: 0,
+        limit: 10,
+        order_by: 0,
+        order: :asc
+      }
+
+      send(widget.pid, {:get_rows, self(), spec})
+
+      assert_receive {:rows,
+                      %{
+                        columns: [_, _, _, _]
+                      }}
+    end
   end
 
   defp connect_self(widget) do