Struct DrainedChild 

pub struct DrainedChild {
    pub parent_type_id: TypeId,
    pub parent_entry_idx: usize,
    pub child: Box<dyn Any + Send + Sync>,
    pub child_type_id: TypeId,
    pub fk_target_type_id: TypeId,
    pub through_table: Option<String>,
    pub through_parent_fk_col: Option<String>,
    pub through_child_fk_col: Option<String>,
}

A child entity drained from a principal’s HasMany navigation, with the metadata needed to fixup its FK after the principal’s PK is backfilled.

Fields

parent_type_id: TypeId

The principal entity’s TypeId (e.g. Blog).

parent_entry_idx: usize

Index of the principal entry in its DbSet (for PK lookup after INSERT).

child: Box<dyn Any + Send + Sync>

The drained child entity, type-erased.

child_type_id: TypeId

The child entity’s TypeId (e.g. Post).

fk_target_type_id: TypeId

The FK target type for set_foreign_key (the principal type).

through_table: Option<String>

M2M only: the join table name. None for one-to-many.

through_parent_fk_col: Option<String>

M2M only: FK column on the join table pointing to the principal.

through_child_fk_col: Option<String>

M2M only: FK column on the join table pointing to the child.