.NET Decimal -> COM -> VT_DECIMAL -> Unknown

wakestar · 2016-06-23

Hi there

I wrote a .NET assembly which has a COM Interface so I can call it from NAV.

I noticed that .NET decimal type gets marshalled to VT_DECIMAL... but the poor NAV classic client doesn't know what VT_DECIMAL is (VT_UNKNOWN).

According to the help...the NAV type Decimal is mapped to VT_Currency and...

The CURRENCY type in COM is a special data type with a fixed point, which has 15 digits to the left of the point and 4 to the right. You should note that the Decimal type in C/AL does not have a fixed point and can have a total of 18 digits. This could possibly lead to some rounding being performed when a Decimal number is passed to a method that expects a CURRENCY, the server manipulates that number and returns it as a CURRENCY. No matter how many digits the original Decimal had to the right of the decimal point, the returned CURRENCY will have no more than 4 digits.

So my question is:
is there a better way than marshalling the .NET Decimal type to VT_Currency?
Since I'm using my .NET assembly also in the newer versions of NAV with .NET Interop ... I want to keep the decimal datatype in .NET... since that works fine.

Anyone?

archer89 · 2016-06-23

try float or double data type instead.

wakestar · 2016-06-24

Thanks! float seems fine.

May I ask how you handle DateTime? It seems like the time of datetime is lost when marshalled to VT_DATE

archer89 · 2016-06-24

you could convert the datetime value to double using DateTime.ToOADate.
follow http://stackoverflow.com/questions/16262007/datetime-tooadate-time-only

you can then convert the double value back to a datetime value.

kriki · 2016-07-07

[Topic moved from 'NAV/Navision Classic Client' forum to 'NAV Three Tier' forum]

.NET Decimal -> COM -> VT_DECIMAL -> Unknown

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