So I got bit by a breaking change in dbplyr. In 1.4.0 there was a breaking change that impacts where eval happens in dbplyr (local vs on the server).
This code used to work in 1.3 but now breaks:
library(tidyverse)
#> Registered S3 methods overwritten by 'ggplot2':
#> method from
#> [.quosures rlang
#> c.quosures rlang
#> print.quosures rlang
testfun <- function(tab, tst_input){
en_tst <- dplyr::enquo(tst_input)
tab %>%
filter(!!en_tst > 15) -> out
return(out)
}
con <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
copy_to(con, mtcars)
mtcars2 <- tbl(con, "mtcars")
testfun(tab = mtcars2, tst_input = mpg)
#> Error in call[[1]]: object of type 'symbol' is not subsettable
but that's easy enough to fix by replacing
filter(!!en_tst > 15)
with
filter(local(!!en_tst) > 15)
Not a huge deal, but it was really tricky for me to debug. And while I'm not super well versed in tidy development, I'm typically reasonably competent. So I was a little surprised how hard this was to figure out.
In the release notes there's mention of changes that break subsetting:
Subsetting (
[[,$, and[) functions are no longer evaluated locally.
So what changed that makes using !! in dbplyr problematic? Is it the subsetting change mentioned above or is it something else altogether?
FWIW, after the change I mention above, the code works great like this:
library(tidyverse)
#> Registered S3 methods overwritten by 'ggplot2':
#> method from
#> [.quosures rlang
#> c.quosures rlang
#> print.quosures rlang
testfun <- function(tab, tst_input){
en_tst <- dplyr::enquo(tst_input)
tab %>%
filter(local(!!en_tst) > 15) -> out
return(out)
}
con <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
copy_to(con, mtcars)
mtcars2 <- tbl(con, "mtcars")
testfun(tab = mtcars2, tst_input = mpg)
#> # Source: lazy query [?? x 11]
#> # Database: sqlite 3.22.0 [:memory:]
#> mpg cyl disp hp drat wt qsec vs am gear carb
#> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 21 6 160 110 3.9 2.62 16.5 0 1 4 4
#> 2 21 6 160 110 3.9 2.88 17.0 0 1 4 4
#> 3 22.8 4 108 93 3.85 2.32 18.6 1 1 4 1
#> 4 21.4 6 258 110 3.08 3.22 19.4 1 0 3 1
#> 5 18.7 8 360 175 3.15 3.44 17.0 0 0 3 2
#> 6 18.1 6 225 105 2.76 3.46 20.2 1 0 3 1
#> 7 24.4 4 147. 62 3.69 3.19 20 1 0 4 2
#> 8 22.8 4 141. 95 3.92 3.15 22.9 1 0 4 2
#> 9 19.2 6 168. 123 3.92 3.44 18.3 1 0 4 4
#> 10 17.8 6 168. 123 3.92 3.44 18.9 1 0 4 4
#> # … with more rows
Created on 2019-06-07 by the reprex package (v0.3.0)