serializing nested ntbk metadata items

myst_nb/parser.py

@@ -117,7 +117,7 @@ def parse_block(src, start_line):
 
     for cell_index, nb_cell in enumerate(ntbk.cells):
 
-        # if the the source_map ahs been stored (for text-based notebooks),
+        # if the the source_map has been stored (for text-based notebooks),
         # we use that do define the starting line for each cell
         # otherwise, we set a pseudo base that represents the cell index
         start_line = source_map[cell_index] if source_map else (cell_index + 1) * 10000
@@ -162,21 +162,11 @@ def parse_block(src, start_line):
         md.core.process(state)
 
     # Add the front matter.
-    # Note that myst_parser now serialises dict/list like keys, when rendering to
-    # docutils docinfo,
-    # so to stay consistent with the previous code (for now) we strip this data
+    # Note that myst_parser serialises dict/list like keys, when rendering to
+    # docutils docinfo. These could be read back with `json.loads`.
     state.tokens = [
         Token(
-            "front_matter",
-            "",
-            0,
-            content=(
-                {
-                    k: v
-                    for k, v in ntbk.metadata.items()
-                    if isinstance(v, (str, int, float))
-                }
-            ),
+            "front_matter", "", 0, content=({k: v for k, v in ntbk.metadata.items()}),
         )
     ] + state.tokens