escape.md
In dbplyr: A 'dplyr' Back End for Databases

shiny objects give useful errors

Code
  lf %>% filter(a == input$x) %>% show_query()
Condition
  Error:
  ! Cannot translate shiny inputs to SQL.
  i Do you want to force evaluation in R with (e.g.) `!!input$x` or `local(input$x)`?

Code
  lf %>% filter(a == x()) %>% show_query()
Condition
  Error:
  ! Cannot translate a shiny reactive to SQL.
  i Do you want to force evaluation in R with (e.g.) `!!foo()` or `local(foo())`?

con must not be NULL

Code
  escape("a")
Condition
  Error in `escape()`:
  ! `con` must not be NULL.

Code
  sql_vector("a")
Condition
  Error in `sql_vector()`:
  ! `con` must not be NULL.

data frames give useful errors

Code
  escape(mtcars, con = simulate_dbi())
Condition
  Error:
  ! Cannot translate a data.frame to SQL.
  i Do you want to force evaluation in R with (e.g.) `!!df$x` or `local(df$x)`?