Add checks before accessing database

src/ansys/mapdl/core/database/__init__.py

@@ -1,3 +1,3 @@
 """The mapdl database module, allowing the access to the MAPDL database from Python."""
 
-from .database import DBDef, MapdlDb  # noqa: F401
+from .database import DBDef, MapdlDb, check_mapdl_db_is_alive  # noqa: F401

src/ansys/mapdl/core/database/database.py

@@ -1,5 +1,6 @@
 """Contains the MapdlDb classes, allowing the access to MAPDL DB from Python."""
 from enum import Enum
+from functools import wraps
 import os
 import time
 from warnings import warn
@@ -38,6 +39,32 @@ def __exit__(self, *args, **kwargs):
             self._mapdl._resume_routine()
 
 
+def check_mapdl_db_is_alive(function):
+    """
+    Decorator to check that the MAPDL.DB has started.
+
+    It works for the DB object (DBDef) and for the derived object which has "_db" attribute.
+    """
+
+    @wraps(function)
+    def wrapper(self, *args, **kwargs):
+        if hasattr(self, "active"):
+            active = self.active
+        elif hasattr(self, "_db"):
+            active = self._db.active
+        else:  # pragma: no cover
+            raise Exception("The DB object could not be found.")
+
+        if not active:
+            self._mapdl._log.error(
+                f"Please start the MAPDL DB Server to access '{function.__name__}'."
+            )
+            return None
+        return function(self, *args, **kwargs)
+
+    return wrapper
+
+
 class DBDef(Enum):  # From MAPDL ansysdef.inc include file
 
     """Database type definitions."""
@@ -311,6 +338,7 @@ def clear(self, **kwargs):
         return self._mapdl.run("/CLEAR,ALL")
 
     @property
+    @check_mapdl_db_is_alive
     def nodes(self):
         """
         MAPDL database nodes interface.
@@ -380,6 +408,7 @@ def nodes(self):
         return self._nodes
 
     @property
+    @check_mapdl_db_is_alive
     def elems(self):
         """
         MAPDL database element interface.

src/ansys/mapdl/core/database/elems.py

@@ -8,7 +8,7 @@
 
 from ansys.api.mapdl.v0 import mapdl_db_pb2
 
-from . import DBDef, MapdlDb
+from . import DBDef, MapdlDb, check_mapdl_db_is_alive
 
 
 class DbElems:
@@ -66,6 +66,7 @@ def __str__(self):
         lines.append(f"    Maximum element number:      {self.max_num}")
         return "\n".join(lines)
 
+    @check_mapdl_db_is_alive
     def first(self, ielm=0):
         """
         Get the number of the first element.
@@ -99,6 +100,7 @@ def first(self, ielm=0):
         self._itelm = ielm
         return self.next()
 
+    @check_mapdl_db_is_alive
     def next(self):
         """
         Return the number of the next selected element.
@@ -154,6 +156,7 @@ def next(self):
     #     return self._itelm
     ###########################################################################
 
+    @check_mapdl_db_is_alive
     def info(self, ielm, ikey):
         """
         Get information about a element

src/ansys/mapdl/core/database/nodes.py

@@ -12,7 +12,7 @@
 from numpy.lib import recfunctions
 
 from ..common_grpc import DEFAULT_CHUNKSIZE
-from .database import DBDef, MapdlDb
+from .database import DBDef, MapdlDb, check_mapdl_db_is_alive
 
 
 class DbNodes:
@@ -95,6 +95,7 @@ def _db(self):
         """Return the weakly referenced instance of db."""
         return self._db_weakref()
 
+    @check_mapdl_db_is_alive
     def first(self, inod=0):
         """
         Return the number of the first node.
@@ -127,6 +128,7 @@ def first(self, inod=0):
         self._itnod = inod
         return self.next()
 
+    @check_mapdl_db_is_alive
     def next(self):
         """
         Return the number of the next selected node.
@@ -180,6 +182,7 @@ def next(self):
     #     self._itnod = result.inum
     #     return self._itnod
 
+    @check_mapdl_db_is_alive
     def info(self, inod, ikey):
         """
         Return information about a node.
@@ -266,6 +269,7 @@ def info(self, inod, ikey):
         result = self._db._stub.NodInqr(request)
         return result.ret
 
+    @check_mapdl_db_is_alive
     def num(self, selected=False) -> int:
         """
         Return the number of nodes, either selected or all.
@@ -295,6 +299,7 @@ def num(self, selected=False) -> int:
         return self.info(0, DBDef.DB_NUMDEFINED.value)
 
     @property
+    @check_mapdl_db_is_alive
     def max_num(self) -> int:
         """
         Return the maximum node number.
@@ -310,6 +315,7 @@ def max_num(self) -> int:
         """
         return self.info(0, DBDef.DB_MAXDEFINED.value)
 
+    @check_mapdl_db_is_alive
     def coord(self, inod):
         """
         Return the location of a node.
@@ -345,6 +351,7 @@ def coord(self, inod):
         node = self._db._stub.getNod(request)
         return node.kerr, tuple(node.v)
 
+    @check_mapdl_db_is_alive
     def all_asarray(self):
         """
         Return all node indices, coordinates, and angles as arrays.
@@ -442,6 +449,7 @@ def all_asarray(self):
 
         return ind, coord, angle
 
+    @check_mapdl_db_is_alive
     def push(self, inod, x, y, z, xang=None, yang=None, zang=None):
         """
         Push a single node into the DB.

tests/test_database.py

@@ -6,8 +6,6 @@
 from ansys.mapdl.core.database import DBDef, MapdlDb
 from ansys.mapdl.core.misc import random_string
 
-pytestmark = pytest.mark.skip
-
 
 @pytest.fixture(scope="session")
 def db(mapdl):
@@ -215,3 +213,12 @@ def test__channel_str(db):
     assert ":" in db._channel_str
     assert re.search("\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}", db._channel_str)
     assert re.search("\d{4,6}", db._channel_str)
+
+
+def test_off_db(mapdl, db):
+    """Testing that when there is no active database"""
+    if db.active:
+        db.stop()
+    assert not mapdl.db.active
+    assert mapdl.db.nodes is None
+    assert mapdl.db.elems is None