% Generated by roxygen2: do not edit by hand

% Please edit documentation in R/key-helpers.R

\name{check_key}

\alias{check_key}

\title{Check if column(s) can be used as keys}

\usage{

check_key(x, ..., .data = deprecated())

}

\arguments{

\item{x}{The data frame whose columns should be tested for key properties.}

\item{...}{The names of the columns to be checked, processed with

\code{\link[dplyr:select]{dplyr::select()}}. If omitted, all columns will be checked.}

\item{.data}{Deprecated.}

}

\value{

Returns \code{x}, invisibly, if the check is passed.

Otherwise an error is thrown and the reason for it is explained.

}

\description{

\code{check_key()} accepts a data frame and, optionally, columns.

It throws an error

if the specified columns are NOT a unique key of the data frame.

If the columns given in the ellipsis ARE a key, the data frame itself is returned silently, so that it can be used for piping.

}

\examples{

data <- tibble::tibble(a = c(1, 2, 1), b = c(1, 4, 1), c = c(5, 6, 7))

# this is failing:

try(check_key(data, a, b))

# this is passing:

check_key(data, a, c)

check_key(data)

}