Monday, June 04, 2007

Flex support for [Flags] enum - not

My last post showed how to get explicit semantics in a WCF contract description using [Flags] enum. As readers of my blog may know, our main service consumer is a Flex 2.x client. As it turns out, Flex has an issue with correctly interpreting such enumerations.

A [Flags] enum looks like this in the WSDL:

<s:simpleType name="DisciplineFlags">
<s:restriction base="s:string">
<s:enumeration value="None" />
<s:enumeration value="Administration" />
. . .

The correct input format for an element that uses the above type is XML whitespace separated values, such as "None Administration". Flex, on the other hand, interprets the list schema construct too litterally, and tries to pass in an array. This causes an exception in the WCF service, as the message cannot be deserialized due to the incorrect XML.

As the Flex guys had no other solution to this problem, I just added a simple "FlexDisciplineFlags" string property to the contract. Flex has to pass a CSV list of the filter enum values, and the service will "cast" the input into the official filter condition:

private void HackFlexIssues(DocumentCardFilter filter)
if (String.IsNullOrEmpty(filter.FlexDisciplineFlags)==false)
//input string must be a CSV-list of enum items
filter.DisciplineFlags = (DisciplineFlags)Enum.Parse(typeof(DisciplineFlags), filter.FlexDisciplineFlags, false);

Note that I'm kind of making a workaround for a technical limitation, maybe I'll get sued by Adobe :)

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