5.3. Accessing the Database from the Python Code

Within your UPF routine, you may need to access the Mechanical APDL database in read/write mode.

In the Python code, you can create a connection with the DB server. This command must be called only once, so you can protect the call based on the value of a static variable:

import grpc
import sys
from mapdl import *

firstcall = 1

class MapdlUserService(MapdlUser_pb2_grpc.MapdlUserServiceServicer):
    

#   ###############################################################
    def UserMat( self, request, context):
        
        global firstcall
        
        if firstcall == 1:
            print( ">> Connection to the MAPDL DB Server\n")
            db.start()
            firstcall = 0

        # continuation of the python function
        # …

Once the DB connection has been initialized, you can access the database of the Mechanical APDL instance in read/write mode.

A subset of the functions documented in Accessing the Mechanical APDL Database have been exposed and can be called from the Python code. Below is a list of those functions:

Supported Database Access Functions
`db.start()`	Initializes the connection with a running Mechanical APDL instance. The DB Server is automatically started in Mechanical APDL if a /UPF command with a python file has been detected.
`db.stop()`	Closes the connection with the DB Server.
`db.ndnext(next)`	Equivalent to the function described in Function ndnext (Getting the Next Node Number)
`db.ndinqr(ind, key)`	Equivalent to the function described in Function ndinqr (Getting Information About a Node)
`db.getnod(inod)`	Equivalent to the function described in Function getnod (Getting a Nodal Point)
`db.putnod(inod, x, y, z)`	Equivalent to the function described in Function putnod (Storing a Node)
`db.elnext(ielm)`	Equivalent to the function described in Function elnext (Getting the Number of the Next Element)
`db.getelem(ielm)`	Equivalent to the function described in Function elmget (Getting an Element's Attributes and Nodes)
`db.get_ElmInfo(inquire)`	Equivalent to the function get_ElmInfo described in Accessing Solution and Material Data
`db.get_ElmData(kchar, elemId, kMatRecPt, ncomp, vect)`	Equivalent to the function get_ElmData described in Accessing Solution and Material Data
`db.putElmData(inquire, elemId, kIntg, nvect, vect)`	Equivalent to the function put_ElmData described in Accessing Solution and Material Data