Function with_effective_values

apps/channels/managers.py:28–55

Annotate the channels queryset with `effective_*` columns that resolve to the override value when set, otherwise fall back to the channel's own value. Always eagerly loads the override one-to-one to avoid N+1 when the caller reads annotated attributes and then the related override.

(queryset, select_related_fks=False)

def with_effective_values(queryset, select_related_fks=False):
    """
    Annotate the channels queryset with `effective_*` columns that resolve to
    the override value when set, otherwise fall back to the channel's own
    value. Always eagerly loads the override one-to-one to avoid N+1 when the
    caller reads annotated attributes and then the related override.

    Pass `select_related_fks=True` when the output path will access FK objects
    through the `effective_*_obj` Channel properties; this pulls the override's
    logo, channel_group, epg_data, and stream_profile in the same query so
    those accessors do not trigger per-row lookups.
    """
    annotations = {
        f"effective_{field}": Coalesce(
            f"override__{field}",
            field,
        )
        for field in OVERRIDABLE_FIELDS
    }
    qs = queryset.select_related("override").annotate(**annotations)
    if select_related_fks:
        qs = qs.select_related(
            "override__logo",
            "override__channel_group",
            "override__epg_data",
            "override__stream_profile",
        )
    return qs