From 6aa06d2f43da7c4d310a219e95a5ac368642f112 Mon Sep 17 00:00:00 2001
From: Erik Frey <erikfrey@google.com>
Date: Mon, 22 Sep 2025 10:26:22 -0700
Subject: [PATCH] Add `_all_fields` to MjOption, MjModel, MjData for struct
 introspection.

PiperOrigin-RevId: 810066486
Change-Id: I807104fc955a505512287f63b7c184a29c0d150e
---
 python/mujoco/structs.cc | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/python/mujoco/structs.cc b/python/mujoco/structs.cc
index 6f157d02..62ac789c 100644
--- a/python/mujoco/structs.cc
+++ b/python/mujoco/structs.cc
@@ -97,6 +97,19 @@ PYBIND11_MODULE(_structs, m) {
   mjOption.def("__deepcopy__", [](const MjOptionWrapper& other, py::dict) {
     return MjOptionWrapper(other);
   });
+  mjOption.def_property_readonly_static("_all_fields", [](py::object) {
+    std::vector<std::string> fields;
+#define X(dtype, name) fields.push_back(#name);
+    MJOPTION_FLOATS
+#undef X
+#define X(name, dim0) fields.push_back(#name);
+    MJOPTION_VECTORS
+#undef X
+#define X(dtype, name) fields.push_back(#name);
+    MJOPTION_INTS
+#undef X
+    return py::tuple(py::cast(fields));
+  });
   DefineStructFunctions(mjOption);
 
 #define X(type, var)                                               \
@@ -417,6 +430,17 @@ This is useful for example when the MJB is not available as a file on disk.)"));
     return py::tuple(py::cast(fields));
   });
 
+  mjModel.def_property_readonly_static("_all_fields", [](py::object) {
+    std::vector<std::string> fields;
+#define X(var) fields.push_back(#var);
+    MJMODEL_INTS
+#undef X
+#define X(type, name, nr, nc) fields.push_back(#name);
+    MJMODEL_POINTERS
+#undef X
+    return py::tuple(py::cast(fields));
+  });
+
 #define X(dtype, var, dim0, dim1)                        \
   if constexpr (std::string_view(#var) != "text_data" && \
                 std::string_view(#var) != "names" &&     \
@@ -748,6 +772,17 @@ This is useful for example when the MJB is not available as a file on disk.)"));
         py::cast(other.model()).attr("__deepcopy__")(memo);
     return MjDataWrapper(other, new_model_py.cast<MjModelWrapper*>());
   });
+  mjData.def_property_readonly_static("_all_fields", [](py::object) {
+    std::vector<std::string> fields;
+#define X(dtype, name) fields.push_back(#name);
+    MJDATA_SCALAR
+#undef X
+#define X(dtype, name, dim0, dim1) fields.push_back(#name);
+    MJDATA_VECTOR
+    MJDATA_POINTERS
+#undef X
+    return py::tuple(py::cast(fields));
+  });
   mjData.def(py::pickle(
       [](const MjDataWrapper& d) {  // __getstate__
         std::ostringstream output(std::ios::out | std::ios::binary);