[FEM] Elmer: fix pipeline update issue

- the existing result pipeline can have several children. They must all be updated.

src/Mod/Fem/App/FemPostPipeline.cpp

@@ -226,6 +226,12 @@ void FemPostPipeline::onChanged(const Property* prop)
 
 }
 
+void FemPostPipeline::recomputeChildren()
+{
+    for (const auto &obj : Filter.getValues())
+        obj->touch();
+}
+
 FemPostObject* FemPostPipeline::getLastPostObject() {
 
     if (Filter.getValues().empty())

src/Mod/Fem/App/FemPostPipeline.h

@@ -64,11 +64,12 @@ public:
     void load(FemResultObject* res);
 
     //Pipeline handling
-    FemPostObject* getLastPostObject();
-    bool           holdsPostObject(FemPostObject* obj);
+    void recomputeChildren();
+    FemPostObject *getLastPostObject();
+    bool holdsPostObject(FemPostObject *obj);
 
 protected:
-    virtual void onChanged(const App::Property* prop);
+    virtual void onChanged(const App::Property *prop);
 
 private:
     static const char* ModeEnums[];

src/Mod/Fem/App/FemPostPipelinePy.xml

@@ -28,6 +28,11 @@
                 <UserDocu>Load a result object</UserDocu>
             </Documentation>
         </Methode>
+        <Methode Name="recomputeChildren">
+            <Documentation>
+                <UserDocu>Recomputes all children of the pipeline</UserDocu>
+            </Documentation>
+        </Methode>
         <Methode Name="getLastPostObject">
             <Documentation>
                 <UserDocu>Get the last post-processing object</UserDocu>

src/Mod/Fem/App/FemPostPipelinePyImp.cpp

@@ -77,6 +77,15 @@ PyObject* FemPostPipelinePy::load(PyObject *args)
     Py_Return;
 }
 
+PyObject *FemPostPipelinePy::recomputeChildren(PyObject *args)
+{
+    if (!PyArg_ParseTuple(args, ""))
+        return nullptr;
+
+    getFemPostPipelinePtr()->recomputeChildren();
+    Py_Return;
+}
+
 PyObject* FemPostPipelinePy::getLastPostObject(PyObject *args)
 {
     if (!PyArg_ParseTuple(args, ""))

src/Mod/Fem/femsolver/elmer/tasks.py

@@ -256,6 +256,7 @@ class Results(run.Results):
         # this might be changed in future, therefore leave this
         #self.solver.ElmerResult.scale(1000)
         self.solver.ElmerResult.getLastPostObject().touch()
+        self.solver.ElmerResult.recomputeChildren()
         self.solver.Document.recompute()
 
     def _createResults(self):