Feature request: Hidden slots & values when exporting

[Takadonet]

Is it possible in schema_enums/schema_slots tsv files that you can have a hidden column(s) with default value(s) that are sent when an user clicks on export/save as?

Example :
Column lab_received with value 3453 for each rows when exporting/save as.

I know this can be done in the export.js to each specific template . Issue with that approach is that someone with knowledge of JavaScript has to add theses values in. Our goal is to have a non IT background for creating/editing all values schema_enums/schema_slots**** files to be exported from DH. It becomes less magic from their point of view since they can see in the schema tsv files that the values are there.

[ddooley]

First, possibly we could use LinkML's facility for default values for fields. One issue is whether people are allowed to keep a field empty, which would clash with adding a default value for any existing records. Possibly we only have the default value thing kick in for newly added records. See #316

Second, we should find out if LinkML wants to add UI annotations to slots such as "hidden field". This and the above function could accomplish what you want without any custom coding.