new feature jupytext-config unset-default-viewer

jupytext/jupytext_config.py

@@ -55,15 +55,33 @@ def fill_parser(self, subparser):
         subparser.add_argument(
             "doctype",
             nargs="*",
-            help=f"the document types to be associated with the notebook editor. "
-            f"Defaults to {' '.join(LabConfig.DOCTYPES)}",
+            help=f"the document types to be associated with the notebook editor; "
+            f"defaults to {' '.join(LabConfig.DOCTYPES)}",
+        )
+
+
+class UnsetDefaultViewer(SubCommand):
+    def __init__(self):
+        super().__init__("unset-default-viewer", "Unset default viewers for JupyterLab")
+
+    def main(self, args):
+        LabConfig().read().unset_default_viewers(args.doctype).write()
+        return 0
+
+    def fill_parser(self, subparser):
+        subparser.add_argument(
+            "doctype",
+            nargs="*",
+            help=f"the document types for which the default viewer will be unset; "
+            f"defaults to {' '.join(LabConfig.DOCTYPES)}",
         )
 
 
 # create the subcommands
 SUBCOMMANDS = [
     ListDefaultViewer(),
     SetDefaultViewer(),
+    UnsetDefaultViewer(),
 ]
 
 

jupytext/labconfig.py

@@ -82,6 +82,21 @@ def set_default_viewer(self, doctype):
         if doctype not in viewers:
             viewers[doctype] = "Jupytext Notebook"
 
+    def unset_default_viewers(self, doctypes=None):
+        if not doctypes:
+            doctypes = self.DOCTYPES
+        for doctype in doctypes:
+            self.unset_default_viewer(doctype)
+        return self
+
+    def unset_default_viewer(self, doctype):
+        viewers = self.config.get("@jupyterlab/docmanager-extension:plugin", {}).get(
+            "defaultViewers", {}
+        )
+        if doctype not in viewers:
+            return
+        del viewers[doctype]
+
     def write(self) -> bool:
         """
         write the labconfig settings file