Drupal version 8.

The issue is that adding a base field to a custom entity type in code would result in an issue of unique constraint violation as there does not seem to be a way to preset the value to the newly added field.

**setInitialValue()** would set the same value for all the existing entities triggering a constraint violation.

**setInitialValueFromField()** would not do any good as it would only allow fetching value from fields of same type. Otherwise it would be possible to utilise the value from an **id** field and then replace those initial values with something more suitable.

Is there any meaningful way for doing that?