Type-bind fields do not load default values from the Item Template

[jesielviana]

Describe the bug

In DSpace, an Item Template allows repository administrators to define default metadata values for items submitted to a specific Collection. However, fields that use type-bind do not load their default values from the template. When the submission form is rendered, the type-bind field appears empty instead of being pre-filled with the defined default value.

To Reproduce

Steps to reproduce the behavior:

1. Create an Item Template in a Collection and set a default value for a field that uses type-bind.
2. Start a new submission in that Collection.
3. Select a type value that triggers the type-bind field to appear.
4. Navigate to the step containing the type-bind field.
5. Observed result: The type-bind field is empty — the default value defined in the Item Template is not loaded.

Expected behavior

The type-bind field should be automatically filled with the default value defined in the Collection’s Item Template, just like other metadata fields.

[jesielviana]

I discovered that this issue seems related to the isAllowedFor method in the DCInput.java class.
This method is called in populateAllowedFieldNames of the DCInputSet.java class.
I’m not entirely sure why isAllowedFor is implemented in this particular way. If someone could help me understand its purpose and usage, I would greatly appreciate it.

For context, these methods are also used in the MetadataValidation.java class.
Thank you for your time and help!

[kshepherd]

the idea behind my implementation here, is that if there is no configured for that DC Input field, it should always be allowed for the in-progress item.

If there is a type-bind configured (i.e. typeBind is NOT empty), then it will check the passed value - which is the item's dc.type value - against the list of allowed types from the submission form element.

I wonder if the issue is about when the dc.type value is set... is the templated value being "validated away" because there is no item type at the time of reading the value?

[jesielviana]

Thanks @kshepherd, I think the issue occurs because there is no item type at the time the value is read.
In this line, the value for documentType is retrieved, but it is always empty. As a result, any field with a type binding does not load its value from the template item.

The form is populated before it is fully loaded, so there is no selected value for dc.type (unless it is already filled in the template item).

I believe it should be possible to populate all fields from the template item, since the logic that determines whether a type-bound field is shown or hidden is handled on the UI side. The server-side population occurs just before the form is displayed.

If all fields are populated when building the form, any field with a type binding that already has a value from the template item will be shown with that value once the user selects the matching type.