Wednesday, 8 October 2008

Type Safety with Sage

One problem that is often encountered by developers using the Sage Data Objects component is the issue of type safety. If you set the wrong type to a value of a field the software will either throw a runtime exception or, ignore the value you set in. Runtime exceptions can be seen easily, but ignored values are more problematic.

Here is an example of the problem, in Visual Basic.NET

InvPost.Header("Items_Net").value = 13

? InvPost.Header("Items_Net").value

4.7229610327708223E+275 {Double}

[Double]: 4.7229610327708223E+275 {Double}

InvPost.Header("Items_Net").value = CType(13,Double)

? InvPost.Header("Items_Net").value

13.0 {Double}

[Double]: 13.0 {Double}

Here, Items_Net is expecting a floating point value, but when assigned with an integer, it ignores the value, and does not throw an exception. Converting the type to a double, and the code works as expected.

To avoid this, you should be familiar with the types of all the fields that you use, and to do so, you should study the schema for your particular version of Sage, as explained in this link

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