Content parts with get-only collections can't retain their values (JOptions configuration)

[sarahelsaig]

Describe the bug

Right now if your content elements contain any get-only collections, those don't get populated by System.Text.Json. they are just left empty. This is an unintended breaking change compared to Newtonsoft.

Why have get-only collection props in the first place? See the explanation in the static code analysis warning CA2227: Collection properties should be read only.

To Reproduce

1. Have a model that contains a get-only collection property, such as this one.
2. Add it to a content type, create and save a content item with some strings in the collection property.
3. Load it back from the DB.
4. Observe that the collection is now empty

Expected behavior

In Newtonsoft get-only collections (lists, dictionaries, etc) are automatically populated (see mode on the comparison here).

Solution

JOptions.Base should contain the configurations:

• PreferredObjectCreationHandling = JsonObjectCreationHandling.Populate
• ReferenceHandler = null

Note: I'm not entirely sure what the second one means, but it's necessary otherwise the site crashes with the message "System.InvalidOperationException: JsonObjectCreationHandling.Populate is incompatible with reference handling." (see). I suspect it's about handling circular references, but I'm not sure. If anyone has some insight, please chime in.

Screenshots

A minimal sample (not using OC) to show the problem (the "B.Items") and solution (the "B.Items (with options)").

A real life example in Lombiq Content Editors for Orchard Core.

[MikeAlhayek]

Yes. As a workaround, add init; to the property and it will get populated. This is also documented in the 1.9 release. Your fix is good, but not sure if it has impact to other options.