Improve Default Values for Select, Radio Buttons, Check Boxes and Toggle

[deanleigh]

Working with built-in list-based property editors (Dropdown, Radio Button List, Checkbox List, and Toggle) reveals a number of inconsistencies around defaults, value handling, and overall behaviour.

Options are defined using prevalues, but they are typically treated as simple strings, meaning the displayed label and stored value are often the same. There is no standardised way to define or work with structured values, and approaches differ between editors.

Default values are also inconsistent or missing entirely. In most cases, they are not true defaults but rather an initial UI state applied only when the editor is first loaded. They are not reliably applied when content is created programmatically or via APIs, which can lead to unexpected or empty values.

Multi-select editors such as Checkbox Lists further highlight gaps, as they rely on arrays or serialized values without providing a clear or intuitive way to define or validate defaults.

Overall, there is no unified or predictable model for handling defaults, values, and configuration across these editors, leading to additional complexity for developers and inconsistent experiences for content editors.

[skttl]

Related: #21076

[suedeapple]

How uncanny - I wrote a post about this issue on LinkedIn today. https://www.linkedin.com/posts/suedeapple_umbraco-activity-7463136517503348736-XsrX