Is an input's value a usable, non-empty string?

The check for the column-selecting inputs, whose "nothing chosen" state is the empty string rather than NULL. A Shiny input that has not reported yet is NULL, and both nzchar(NULL) and NULL == "" are logical(0), which makes if (...) an error rather than FALSE; this returns FALSE instead.

Usage

nz_value(x)

Arguments

x

A value from a Shiny input.

Value

TRUE for a length-1, non-NA, non-empty character scalar; FALSE for anything else, NULL included.

See also

blank_to_null()

Author

Jared Andrews

Examples

nz_value(NULL)
#> [1] FALSE
nz_value("")
#> [1] FALSE
nz_value(NA_character_)
#> [1] FALSE
nz_value("Species")
#> [1] TRUE