The compare page shows what changed between two versions of the same resource.
Opening a comparison
- From the Version History tab or the browse table, click Diff (or the magnifier icon) on a version. This compares it with the version immediately before it.
- From a version's snapshot page, click Compare with previous.
- To compare two arbitrary versions, open
/admin/resource-versioning/compare/<a>/<b>whereaandbare version row ids of the same resource. When the resource has more than two versions, the compare page also shows a Compare ... with ... picker: choose two versions and click Go.
The two versions are always shown older first, as Before and After, whichever order they were requested in. Comparing the very first version shows "No earlier version" on the Before side and lists everything as added.
Reading the diff
The Changes section has two tables.
The first table lists top-level fields with Before and After columns:
| Field | What is compared |
|---|---|
| Title | The o:title string |
| Is public | Visibility, shown as yes or no |
| Resource class | Class label and term, for example Image (dctype:Image) (#2) |
| Resource template | Template label |
| Thumbnail | Asset name |
| Owner | User name |
| Primary media | Media title |
| Item sets | The set of item set titles the item belongs to |
| Media | The set of media attached to an item |
| Sites | The set of sites a resource is assigned to |
Labels for these references are looked up live from the database when the page renders, because snapshots store only the id. If the referenced class, template, asset, or resource has since been deleted, the bare id is shown instead, for example #2.
The second table lists metadata properties whose values changed. Each row shows the property label and term (for example Title dcterms:title), with removed values struck through and added values underlined. A value's language tag is shown after it when present. Values are matched as a multiset by type, language, and content, so reordering identical values is not reported as a change. Linked resource values show the linked resource's title and id; URI values show their label and URI.
A summary line under the tables counts changed fields, changed properties, values added, and values removed. If nothing differs, the page says No differences between these versions.
Values longer than 500 characters are truncated in the structured view.
Raw JSON diff
Below the structured view, Raw JSON diff shows a line-by-line comparison of the two stored snapshots, with the volatile keys (@context, @id, o:created, o:modified, and so on) removed and object keys sorted so that only real differences appear. Use it to inspect keys that the structured view does not label, such as values added by other modules. Click the summary line to collapse it.
Restoring from the compare page
Editors and above see a Restore version N button that restores the Before version. It is not shown when the Before version is a deletion snapshot. See Restoring a Version.