You use the Tagged Value editor in MDriven Designer to add and edit metadata on a model element, with suggestions and help filtered for the type of element you selected.
Tagged values (TVs) are UML extension metadata. MDriven uses them for information that is not represented by a standard UML property, and you can also use them for metadata that is meaningful in your own model.
Use the Tagged Value editor
The Tagged Value editor appears wherever you access tagged values for a model element. The available suggestions depend on the type of element you are working with.
For example, when you work on a ViewModel column, the editor can help you select presentation-related tags. A StringFormat tagged value can convey formatting instructions for supported UI technologies; see Documentation:Text formatting for the platform-specific values and examples.
- Select the model element whose tagged values you want to inspect or change.
- Open its tagged values. The Tagged Value editor opens for that element.
- Select an available tagged value, or enter the tagged value required by your model.
- Enter or select its value.
- Save the model.
The editor recognizes the selected element type and filters the suggested options accordingly. It also displays a short usage hint for a recognized tagged value.
Refresh the Designer guidance
Use Refresh From Wiki in the Tagged Value editor to download the current tagged-value help and templates maintained at Documentation:MDrivenDesignerTaggedValueHints. This updates the guidance available in your Designer; it does not replace the tagged values already stored in your model.
- Open the Tagged Value editor.
- Click Refresh From Wiki.
- Review the refreshed suggestions and usage hints when adding or editing a tagged value.
The hints are intended to guide MDriven Designer about which tagged values are valid for which target types. The hints use a target-type-oriented naming convention, described on Documentation:MDrivenDesignerTaggedValueHints.
Work with defined value choices
Some tagged values have multiple predefined values. For these tags, the editor can offer the defined values instead of requiring you to remember and type every value. Choose one of the offered values when it matches the behavior you need.
For example, a custom tag extension can define picker values such as important and not important. Such metadata can help you identify model elements that require later work. The same tag can then be used by model logic or tooling to find those elements consistently.
Use tagged values deliberately
A tagged value is metadata, not a replacement for a normal model property. Prefer a standard Designer property when one represents the setting you need. The tagged-value hints deliberately omit settings that already have Designer properties.
Keep tag names and values consistent across the model. Consistent metadata is easier to find, interpret, and use in model logic.
For example:
- Add
autofocuswith the valuetrueto an input field when it must be selected as it appears in a view. See Documentation:Autofocus for the complete procedure. - Add a formatting tagged value to a ViewModel column when you need to control how a bound value is displayed. See Documentation:Text formatting.
- Use your own model-level tags to mark elements for a shared purpose, such as elements that need later review.
Read tagged values in OCL
You can use tagged values as metadata in OCL expressions.
Thing.taggedvalue('mytaggedvalue')reads a tagged value from a class and returns a string. See Documentation:OCLOperators taggedValue.Thing.taggedValueOnFeature('Attribute1','MyTag')reads a tagged value from a named attribute or association end. See Documentation:OCLOperators taggedValueOnFeature.
These operations make a consistent tag vocabulary important. If one class uses ReviewStatus and another uses reviewstatus, expressions must use the exact tag name stored on each element.