Unpack columns from a wrapped tableSource:
A table in the dm with packed columns.
The column to unpack (unquoted).
A dm, only used to query names of primary and foreign keys.
dm_unpack_tbl() targets a specific column to unpack
from the given table in a given dm.
A ptype or a set of keys should be given,
dm_pack_tbl() is an inverse operation to
if differences in row and column order are ignored.
The opposite is true if referential constraints between both tables
and if all rows in the parent table have at least one child row,
i.e. if the relationship is of cardinality 1:n or 1:1.
flights_wrapped <- dm_nycflights13() %>% dm_wrap_tbl(flights) # The ptype is required for reconstruction. # It can be an empty dm, only primary and foreign keys are considered. ptype <- dm_ptype(dm_nycflights13()) flights_wrapped %>% dm_unpack_tbl(flights, airlines, ptype) #> ── Metadata ──────────────────────────────────────────────────────────────────── #> Tables: `flights`, `airlines` #> Columns: 24 #> Primary keys: 1 #> Foreign keys: 1