Make date configurable in latex/PDF (#1963)

Co-authored-by: Achim Gädke <achimgaedke@users.noreply.github.com>

docs/source/usage.rst

@@ -89,6 +89,34 @@ LaTeX
 
     Latex report, providing a table of contents and chapters.
 
+  Optionally you can specify ``authors``, ``title`` and ``date`` in the notebook's
+  metadata. These will be used to render the header of the LaTeX document.
+
+  .. code-block:: json
+
+      {
+          "authors": [
+              {
+                  "name": "Jane Doe"
+              },
+              {
+                  "name": "John Doe"
+              }
+          ],
+          "date": "January 2023",
+          "title": "Annual Data Report 2022",
+          "kernelspec": { },
+          "language_info": { }
+      }
+
+  If no date is specified, today's date will be used (i.e. the date when the
+  document is re/compiled). Use an empty string to suppress the date.
+
+  The values in the notebook can be overridden by the command line arguments
+  ``--LatexPreprocessor.title``, ``--LatexPreprocessor.date`` and
+  ``--LatexPreprocessor.author_names`` (specify this argument multiple times
+  for each individual author name).
+
   .. note::
 
     nbconvert uses pandoc_ to convert between various markup languages,

nbconvert/preprocessors/latex.py

@@ -14,7 +14,7 @@
 # -----------------------------------------------------------------------------
 
 
-from traitlets import Unicode
+from traitlets import List, Unicode
 
 from .base import Preprocessor
 
@@ -26,10 +26,28 @@
 class LatexPreprocessor(Preprocessor):
     """Preprocessor for latex destined documents.
 
-    Mainly populates the ``latex`` key in the resources dict,
+    Populates the ``latex`` key in the resources dict,
     adding definitions for pygments highlight styles.
+
+    Sets the authors, date and title of the latex document,
+    overriding the values given in the metadata.
     """
 
+    date = Unicode(
+        None,
+        help=("Date of the LaTeX document"),
+        allow_none=True,
+    ).tag(config=True)
+
+    title = Unicode(None, help=("Title of the LaTeX document"), allow_none=True).tag(config=True)
+
+    author_names = List(
+        Unicode(),
+        default_value=None,
+        help=("Author names to list in the LaTeX document"),
+        allow_none=True,
+    ).tag(config=True)
+
     style = Unicode("default", help="Name of the pygments style to use").tag(config=True)
 
     def preprocess(self, nb, resources):
@@ -51,4 +69,14 @@ def preprocess(self, nb, resources):
             "pygments_definitions", LatexFormatter(style=self.style).get_style_defs()
         )
         resources["latex"].setdefault("pygments_style_name", self.style)
+
+        if self.author_names is not None:
+            nb.metadata["authors"] = [{"name": author} for author in self.author_names]
+
+        if self.date is not None:
+            nb.metadata["date"] = self.date
+
+        if self.title is not None:
+            nb.metadata["title"] = self.title
+
         return nb, resources

share/templates/latex/base.tex.j2

@@ -179,7 +179,11 @@ override this.-=))
     ((*- set nb_title = nb.metadata.get('title', '') or resources['metadata']['name'] -*))
     \title{((( nb_title | escape_latex )))}
     ((*- endblock title *))
-    ((* block date *))((* endblock date *))
+    ((* block date *))
+    ((* if 'date' in nb.metadata *))
+    \date{((( nb.metadata.date | escape_latex )))}
+    ((* endif *))
+    ((* endblock date *))
     ((* block author *))
     ((* if 'authors' in nb.metadata *))
     \author{((( nb.metadata.authors | join(', ', attribute='name') )))}