OLEVariants problem
lazarus / 16-Databases

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daveinhull · 2019-02-18 07:54

Hi,

I have a problem with an OLEVariant (connects to Excel).
When I cloase a particualr form I want to make sure that the Excel
object is also closed, so I have used
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i If
ExcelServer <> Unassigned thenbegin  ExcelServer.ActiveWorkbook.Close
(False);  if ExcelServer.Workbooks.Count = 0 then   
ExcelServer.Quit;    ExcelServer := Unassigned;  end....
Which is ok if the ExcelServer was never assigned during the program
execution, i.e. the user didn't want to do anything with Excel.

However, it fails with an "Invalid Variant Operation Displatch =
Empty" message if I actually do setup a link to Excel.
If I change the code
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i if
ExcelServer <> Null then it also fails.

Anybody got any thoughts in this?

Dave

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rvk · 2019-02-18 11:32

Maybe
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i if not
VarIsEmpty(ExcelServer) then

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Thaddy · 2019-02-18 13:16

I expected VarNull or VarEmpty

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rvk · 2019-02-18 13:48

VarIsEmpty checks for VarEmpty. It's just a wrapper for the check. You
shouldn't check for VarEmpty directory.

QuoteVarIsEmpty returns true if the given variant contains the value
Unassigned.
So to make sure you could also do
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i if not
VarIsNullthen(ExcelServer) and not VarIsEmpty(ExcelServer) then //...
O yeah, to make it more confusing there is also VarIsClear()

Also note the function:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
VarIsEmpty(const V: Variant): Boolean;begin 
Result:=TVarData(V).vType=varEmpty;end;
So that's something different from
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i if Variant
<> varEmpty then ... // <-- incorrect
SoCheck for unassigned with VarIsEmpty.Check for an undefined value
with VarIsClear.Check for a null value with VarIsNull.

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daveinhull · 2019-02-19 01:56

Thanks guys,

This worked
Quote from: rvk on February 18, 2019, 12:32:12 pmMaybe
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i if not
VarIsEmpty(ExcelServer) then
And thanks for the other info as well, all useful learning 

Dave