问题
I am very new to programming and this is my first question on stackoverflow. I am trying to make python open an .accdb file and run a subroutine which is already defined in Access. I manage to do it with Excel using this code:
import win32com.client
xl=win32com.client.Dispatch("Excel.Application")
xl.Visible=True
xl.Workbooks.Open(Filename="<mydirectory>\\open",ReadOnly=1)
xl.Application.Run("TestMe")
#...access spreadsheet data...
xl.Workbooks(1).Close(SaveChanges=0)
xl.Application.Quit()
xl=0
The Sub TestMe looks like this:
Sub TestMe()
MsgBox "Hi there"
End Sub
Running the Python code promtly launches Excel, opens the file open.xlsm and displays a messagebox. So far so good. Thanks to: Need skeleton code to call Excel VBA from PythonWin
I've modified the code to try to acheive the same with Access. I made a new .accdb file called "testdb" and copied the above subroutine "TestMe" into a VBA module. The modified python code looks like this:
import win32com.client
xl=win32com.client.Dispatch("Access.Application")
xl.Visible=True
xl.OpenCurrentDatabase("<mydirectory>\\testdb.accdb")
xl.Application.Run("TestMe")
#...access spreadsheet data...
xl.Workbooks(1).Close(SaveChanges=0)
xl.Application.Quit()
xl=0
The main change is that "Workbooks.Open" has changed to "OpenCurrentDatabase". I first tried to find something more similar, like "Databases.Open", but with no luck. Running the new code launches Access and opens the file testdb.accdb, but that's it, no messagebox appears. The only Console output I can imagine is of any interest is:
xl.Application.Run("TestMe")
File "<COMObject <unknown>>", line 14, in Run
result = self._oleobj_.InvokeTypes(*(dispid, LCID, wFlags, retType, argTypes) + args)
pywintypes.com_error: (-2147352567, 'Exception occurred.', (0, None, None, None, 0, -2147352562), None)
I am quite at a loss. Any help would be greatly appreciated!
回答1:
Consider creating a new Access macro object with a RunCode action that calls the function in the module. Then, call the macro in Python's Windows COM API using use the DoCmd.RunMacro method.
MACRO
Macro
RunCode: TestMe()
NOTE: Only functions can be referenced with RunCode not subroutines unless you create a VBA module function that calls the subroutine: Call SubroutineName:
Python
import win32com.client
ac = win32com.client.Dispatch("Access.Application")
ac.Visible=True
ac.OpenCurrentDatabase("<mydirectory>\\testdb.accdb")
ac.DoCmd.RunMacro('MacroName')
ac.DoCmd.CloseDatabase
ac = None
回答2:
I am by no means an expert in Python but have reasonable familiarity with Access and Excel VBA. If I knew Python better and earlier in my amateur programming career I would never have attempted to do what I set out to do below using any VBA code at all. Given the investment in time in VBA code I had to find a way....
I have spent the last several days/week trying to find a way to talk Python->Access VBA with the following requirements:
- call Access VBA function from Python
- send parameter to Access VBA function from Python
- return value from Access VBA function to Python
I made attempts with clr using pythonnet and IronPython and found more and more confusing and unclear error messages and exceptions. I tried the above suggested DoCmd.RunMacro method but Access macros do not return values. Tried a new(ish) version of Access macros (2010) called data macros which do have an action called SetReturnVar but they do not talk to VBA unless through the more traditional macros and as I mentioned above, traditional macros do not return values. Today I read some Microsoft documentation (Access Application.Run method) more carefully:
Access Application.Run method
I am not completely aware of the implications of that statement "you can't set a reference to an individual Microsoft Access database from any application other than Microsoft Access" but it occurred to me that a lot of the Python<->Office Application articles seemed more successful when talking Python<->Excel VBA. I reasoned that because I had been able to run Excel VBA <-> Access VBA in the past and if Python <-> Excel VBA worked as well as I had read, then a solution (albeit convoluted) seemed possible (I think the proper programmers call it a hack).
After about 1 1/2 hours of cutting/pasting code snippets and debugging:
Python
from win32com.client import Dispatch
FILELOC = r'C:\Users\Desktop\PyExcel.xlsm'
PROGNAME='Excel.Application'
num = 4
#open excel workbook containing VBA code
#...could do more to ensure excel isn't already running
xl = Dispatch(PROGNAME)
xl.Visible = True
#open excel file containing the VBA code
#...could do more to check if file is already open, etc
xl.Workbooks.Open(Filename=FILELOC)
#call to VBA code within excel
rtrn_int = xl.Run("RunCOMObject", num)
#print return value
print(rtrn_int)
#Quit excel-this doesn't work very well and there are articles about
#Python or the COM object not being able to actually remove Excel
#from the task manager
xl.Quit()
Excel VBA
Option Explicit
Private Const ACCESS_FILELOC As String = "C:\Users\Desktop\Test.accdb"
Private Const TEMP_FILELOC As String = "C:\Users\Desktop\TestTemp.accdb"
Function RunCOMObject(intNum As Integer) As Integer
Dim objAcc As Object, objProject As Object
Dim accAppl As Access.Application
Dim MyAppl As String
MyAppl = "Access.Application"
If Not IsRunning(MyAppl) Then 'Access not running, simply start
'up Access and open file
Set accAppl = CreateObject(MyAppl) 'start Access
accAppl.Visible = True
accAppl.OpenCurrentDatabase (ACCESS_FILELOC) 'open file
Else: 'Access is running
On Error Resume Next
Set accAppl = GetObject(, MyAppl) 'assign the running application
'to a variable
On Error GoTo Err_File_Open 'use an error in attempting to rename
'the database of interest to determine if the open file is the
'desired file
Name ACCESS_FILELOC As TEMP_FILELOC 'rename the file of interest
Name TEMP_FILELOC As ACCESS_FILELOC 'file was successfully renamed
'therefore not open
Call NoFileOrOther(accAppl, MyAppl)
End If
Err_File_Open:
'Required Access file is open
RunCOMObject = accAppl.Run("TestLink", intNum) 'run the VBA function in
'Access
accAppl.CloseCurrentDatabase 'close database
accAppl.Quit 'quit Access
Set accAppl = Nothing
End Function
Function IsRunning(ByVal MyAppl As String) As Boolean
Dim applRef As Object
On Error Resume Next 'error occurs if GetObject is unable to find a
'running version of the application
Set applRef = GetObject(, MyAppl) 'attempt to obtain the required
'application object
If Not applRef Is Nothing Then 'if application is already running
Set applRef = Nothing
IsRunning = True
Else 'application is not running
IsRunning = False
End If
Set applRef = Nothing
End Function
Sub NoFileOrOther(accAppl As Access.Application, MyAppl As String)
On Error GoTo Err_No_FileOpen
If accAppl.CurrentProject.Name <> "" Then 'Access active with another a
'different file open
Set accAppl = CreateObject(MyAppl) 'start a new instance of Access
accAppl.Visible = True
accAppl.OpenCurrentDatabase (ACCESS_FILELOC) 'open file
End If
Exit Sub
Err_No_FileOpen:
accAppl.OpenCurrentDatabase (ACCESS_FILELOC) 'in the event of Access
'being active without a database open
End Sub
Access VBA
This is a completely trivial example and belies the amount of code I had already written in Access VBA to warrant this workaround but it serves to demonstrate the methodology
Option Compare Database
Option Explicit
Function TestLink(intNum As Integer) As Integer
TestLink = intNum + 10
End Function
Python Output:
14
Success!!!! The number was initially 4 in Python and was sent as a parameter to Excel and Access where it had 10 added to it before being returned via Excel to Python print(rtrn_int) = 14.
If anyone knows how to definitively (ie through similar rigour demonstrated above) send arguments from Python -> Access VBA and return a value to Python without using Excel VBA as an intermediary I would be very happy to hear from you. Alternatively methods using pythonnet referencing clr would be similarly appreciated.
来源：https://stackoverflow.com/questions/32653792/python-code-for-running-ms-access-module-subroutine