Link versioned history

[maxime-rainville]

Story

As a CMS User I want to view old link instance when looking at previous version of my page so that I can restore old content with confidence.

Acceptance criteria

• LinkField display in ReadOnly view when looking at an older version of the page instead of the "Can not create Link" view.
• Version of link displayed follows whatever logic versioned history follows for other relations.
• Archived Admin uses the same behaviour as Versionned Admin when displaying link.
• LinkField on versioned history view correctly identify if a Link was attached to the page, but the Link was deleted.
• LinkField on versioned history view correctly identify if a Link was not attached to the version of the page currently being viewed.

Note

• We do not have an overarching view of how relations should be displayed in compare view. We will ignore this part for now.
• We considered adding a history tab to the LinkForm, but decided it was out of scope for this card.

Designs

Link field - Overview

Note

The current implementation reuses the same IDs when you change Link Type. This could be a plus ... or a horrible hindrance ... not sure which one yet.

PR

• ENH Better versioned history #209

[sachajudd]

@silverstripeux to look into what this would look like in history.

[maxime-rainville]

Cassie didn't think there was much value beyond making sure the LinkField is usable in the Versioned history view.

[maxime-rainville]

What the diff looks like

What the older version looks like

[GuySartorelli]

PR merged