Programming Social Applications

Enum Data Types

With the enum data type, a developer can include a number of user-specified values within a single UserPref element. You can think of this type as an HTML drop-down list that allows the user to select a value from several different choices.

For example, let’s say we’re building a movie-rating widget and want to allow users to store movie ratings from 1–5 (with 0 meaning the user did not rate the movie). We could increase the base UserPref node with our additional EnumValue nodes:

<UserPref name="rating" display_name="Rating" datatype="enum" default_value="0">
   <EnumValue value="1" display_value="Worst Movie Ever"/>
   <EnumValue value="2" display_value="I just wasted 2 hours of my life"/>
   <EnumValue value="3" display_value="Meh"/>
   <EnumValue value="4" display_value="That was pretty entertaining"/>
   <EnumValue value="5" display_value="Epic"/>
</UserPref>

We specify enum as our data type, and within the UserPref node we define the EnumValue nodes for each rating value the user can choose from. Each node has a display value that the user sees (e.g., “Epic”) and a value that the developer uses to denote the chosen option (e.g., “5”).