Enumerations

Adding enumerations to the model allows you to use them as property types in entities. Although they’re modeled in the same way entities are, you won’t be creating an association to an enumeration … rather, they’ll be available when creating properties in the select list of Type.

To add an enumeration, drag it from the toolbox and drop it on the design surface, renaming as you see fit.

The default value type for an enumeration is Int32, although you can change it to any valid .NET enum value type. Note, though, that if the enum is the type for an identifier property in any class (and, before you say anything, I have seen this), you won’t be able to change it to a type that’s not valid for identifiers. You’ll be given the option, but an error will be thrown and the change will be prevented (there was a point where we considered conditionally disallowing invalid types in the value type select list, but it turned out to be more confusing than this way).

Adding a value

Adding values is done in the same way as adding properties to an entity.

• Right click the Values category heading right below the name of the enum on the diagram and choose Add new Value .
• Right click the name of the enum and select Add, then Value from its context menu.
• With the Values category heading selected, hit the Insert key
• With any value selected in the enum, hit Enter.

Code for the enum’s values will be generated in the order they appear in the designer. Since order matters unless you add value initializers, the designer allows you to reorder the values by dragging a highlighted value up and down the list.

You can get more control over the generated value by providing an initializer. Not all values need to be initialized, although you will get a warning if you set some but not others.

Removing a value

To remove a value, simply select it and hit the Delete key. It will be removed from the model completely without confirmation.

If enum values are being automatically generated due to the Flags attribute being set on the enum, these will be regenerated so that gaps don’t exist.

Flags

If your enum’s values are flags, the designer has some extra support to make value setting easier.

When adding a new value and the Values are Flags property is true, the designer will initialize the new value’s Value property to the next highest binary number available in the existing list of values. The same will happen if you clear the Value property, since flags have to have numeric values.

And if you don’t have a headache from the overuse of the word value, you are a stronger person than I.

Enumeration properties

Both the enum and the values have property window entries. Properties of the enum itself are:

Context Menu for Values

Right-clicking on an enum displays a Visual Studio context menu with some new choices pertinent to that enum.

Enumeration Value properties

Properies of the enum values are:

Context Menu for Values

Right-clicking on a value displays a Visual Studio context menu with some new choices pertinent to that value.

Adding Values via Code (custom property syntax)

You can quickly add a group of values as text, a great time saver for those cases where you have existing enums that you want to make persistent and add to the model.

The designer exposes a custom property syntax that allows you to specify values. The syntax is simply:

<Name> <= Value>

with an optional comma (,) at the end of each line, exactly as it would be in C#. This lets you cut and paste C# enumeration bodies into the value editor and have the model consume them directly.

To edit the values as text, select the enum and right-click to get its context menu. Choose Add values via Code and you’ll see a small window pop up with the current values:

Add, edit or remove text as required - when you click OK, all the properties will be replaced by the parsed values of the text in that window. Any unrecognized values will be discarded.

Next Step

Associations

Next Step

Adding Model Comments