Fix: Exporting from a SQLFORM.grid with customized search queries

issues #2006

gluon/sqlhtml.py

@@ -2332,6 +2332,10 @@ class SQLFORM(FORM):
                         #fields but not virtual fields
                         sfields = reduce(lambda a, b: a + b,
                             [[f for f in t if f.readable and not isinstance(f, Field.Virtual)] for t in tables])
+                        #use custom_query using searchable
+                        if callable(searchable):
+                            dbset = dbset(searchable(sfields, keywords))
+                        else:
                             dbset = dbset(SQLFORM.build_query(
                                 sfields, keywords))
                         rows = dbset.select(left=left, orderby=orderby,