tech-dm-class.R
In dm: Relational Data Models

## ----setup, include = FALSE----------------------------------------------
source("setup/setup.R")

## ------------------------------------------------------------------------
#  library(nycflights13)
#  library(dm)
#  dm(airlines, airports, flights, planes, weather)

## ------------------------------------------------------------------------
#  library(nycflights13)
#  library(dm)
#  empty_dm <- dm()
#  empty_dm
#  dm(empty_dm, airlines, airports, flights, planes, weather)

## ------------------------------------------------------------------------
#  as_dm(list(
#    airlines = airlines,
#    airports = airports,
#    flights = flights,
#    planes = planes,
#    weather = weather
#  ))

## ----message=FALSE-------------------------------------------------------
#  sqlite_con <- dbplyr::nycflights13_sqlite()
#  
#  flights_dm <- dm_from_con(sqlite_con)
#  flights_dm

## ------------------------------------------------------------------------
#  base_dm <- new_dm(list(
#    airlines = airlines,
#    airports = airports,
#    flights = flights,
#    planes = planes,
#    weather = weather
#  ))
#  base_dm

## ------------------------------------------------------------------------
#  dm_validate(base_dm)

## ------------------------------------------------------------------------
#  flights_dm[["airports"]]

## ------------------------------------------------------------------------
#  dm_has_pk(flights_dm, airports)
#  flights_dm_with_key <- dm_add_pk(flights_dm, airports, faa)
#  flights_dm_with_key

## ------------------------------------------------------------------------
#  dm_has_pk(flights_dm_with_key, airports)

## ------------------------------------------------------------------------
#  dm_get_all_pks(flights_dm_with_key)

## ------------------------------------------------------------------------
#  dm_rm_pk(flights_dm_with_key, airports) %>%
#    dm_has_pk(airports)

## ------------------------------------------------------------------------
#  dm_enum_pk_candidates(flights_dm_with_key, airports)

## ------------------------------------------------------------------------
#  dm_enum_pk_candidates(flights_dm_with_key, flights) %>% dplyr::count(candidate)

## ----error = TRUE--------------------------------------------------------
#  try(
#    dm_add_pk(flights_dm, airports, tzone, check = TRUE)
#  )

## ------------------------------------------------------------------------
#  flights_dm_with_key %>% dm_add_fk(flights, origin, airports)

## ----error=TRUE----------------------------------------------------------
#  try(
#    flights_dm %>% dm_add_fk(flights, origin, airports)
#  )

## ------------------------------------------------------------------------
#  flights_dm_with_fk <- dm_add_fk(flights_dm_with_key, flights, origin, airports)

## ----error=TRUE----------------------------------------------------------
#  try(
#    flights_dm_with_fk %>% dm_add_fk(flights, dest, airports, check = TRUE)
#  )

## ------------------------------------------------------------------------
#  dm_get_all_fks(dm_nycflights13(cycle = TRUE))

## ----error=TRUE----------------------------------------------------------
#  try(
#    flights_dm_with_fk %>%
#      dm_rm_fk(table = flights, column = dest, ref_table = airports) %>%
#      dm_get_all_fks(c(flights, airports))
#  )
#  
#  flights_dm_with_fk %>%
#    dm_rm_fk(flights, origin, airports) %>%
#    dm_get_all_fks(c(flights, airports))
#  
#  flights_dm_with_fk %>%
#    dm_rm_fk(flights, columns = NULL, airports) %>%
#    dm_get_all_fks(c(flights, airports))

## ------------------------------------------------------------------------
#  dm_enum_fk_candidates(flights_dm_with_key, weather, airports)