str_flatten does not work in Redshift

[hdplsa]

The str_flatten function is translated to string_agg when using the Redshift backend. The string_agg function is not supported by Redshift. Instead str_flatten should be translated into LISTAGG.

Will submit a pull request soon! :)

Please see the reprex below:

library(dbplyr)
library(DBI)
library(reprex)

con <- dbConnect(RPostgres::Redshift(), 
                 host = ,
                 dbname = , 
                 port = ,
                 user = , 
                 password = ) 

example_table <- dplyr::tribble(
  ~customer, ~day, ~item,
  "A", 1, "WATER",
  "A", 3, "BREAD",
  "A", 2, "JUICE",
  "B", 1, "APPLE",
  "B", 4, "BANANA",
  "C", 1, "MILK"
)

table_db <- dplyr::copy_to(con, example_table, temporary = T)

table_db %>%
  dplyr::group_by(customer) %>%
  dplyr::summarize(flat_string = str_flatten(item, "-"))
#> Error: Failed to prepare query: ERROR:  function string_agg(character varying, "unknown") does not exist
#> HINT:  No function matches the given name and argument types. You may need to add explicit type casts.

table_db %>%
  dplyr::group_by(customer) %>%
  dbplyr::window_order(day) %>%
  dplyr::mutate(flat_string = str_flatten(item, "-")) 
#> Error: Failed to prepare query: ERROR:  function string_agg(character varying, "unknown") does not exist
#> HINT:  No function matches the given name and argument types. You may need to add explicit type casts.

^{Created on 2022-03-25 by the reprex package (v2.0.0)}