python3Packages.gnucash: Build from existing gnucash package

pkgs/by-name/gn/gnucash/package.nix

@@ -25,8 +25,12 @@
   swig,
   webkitgtk_4_0,
   wrapGAppsHook3,
+  python ? null,
+  enablePython ? false,
 }:
 
+assert enablePython -> (python != null);
+
 stdenv.mkDerivation rec {
   pname = "gnucash";
   version = "5.11";
@@ -45,6 +49,11 @@ stdenv.mkDerivation rec {
     pkg-config
   ];
 
+  cmakeFlags = lib.optional enablePython [
+    "-DWITH_PYTHON=\"ON\""
+    "-DPYTHON_SYSCONFIG_BUILD=\"$out\""
+  ];
+
   buildInputs =
     [
       aqbanking
@@ -68,7 +77,8 @@ stdenv.mkDerivation rec {
       JSONParse
       FinanceQuote
       perl
-    ]);
+    ])
+    ++ lib.optional enablePython python;
 
   patches = [
     # this patch disables test-gnc-timezone and test-gnc-datetime which fail due to nix datetime challenges
@@ -81,6 +91,20 @@ stdenv.mkDerivation rec {
     ./0004-exec-fq-wrapper.patch
   ];
 
+  postPatch = ''
+    patch -p0 <<END_PATCH
+      +++ bindings/python/__init__.py
+      @@ -1,3 +1,7 @@
+      +import os
+      +os.environ['GNC_DBD_DIR'] = '${libdbiDrivers}/lib/dbd'
+      +os.environ['GSETTINGS_SCHEMA_DIR'] = '${glib.makeSchemaPath "$out" "gnucash-${version}"}'
+      +
+       # import all the symbols from gnucash_core, so basic gnucash stuff can be
+       # loaded with:
+       # >>> from gnucash import thingy
+        END_PATCH
+  '';
+
   # this needs to be an environment variable and not a cmake flag to suppress
   # guile warning
   env.GUILE_AUTO_COMPILE = "0";

pkgs/top-level/python-packages.nix

@@ -5605,6 +5605,11 @@ self: super: with self; {
 
   gntp = callPackage ../development/python-modules/gntp { };
 
+  gnucash = toPythonModule (pkgs.gnucash.override {
+    inherit (self) python;
+    enablePython = true;
+  });
+
   gnureadline = callPackage ../development/python-modules/gnureadline { };
 
   go2rtc-client = callPackage ../development/python-modules/go2rtc-client { };