Merge branch 'f-#109-lookup-error'. Closes #109.

- `$` only warns and also performs partial matching if column not found. - `[[` returns `NULL` if column not found.
tidyverse · Jun 30, 2016 · 79cffa3 · hadley · Jun 30, 2016 · 79cffa3
2 parents cea29b6 + 4c3dca3
commit 79cffa3
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Showing 2 changed files with 13 additions and 12 deletions.
diff --git a/R/tbl-df.r b/R/tbl-df.r
@@ -21,9 +21,6 @@ print.tbl_df <- function(x, ..., n = NULL, width = NULL) {
     colname <- i
   else
     colname <- j
-  if (is.character(colname) && length(colname) == 1L && !(colname %in% names(x))) {
-    stopc("Unknown column '", colname, "'")
-  }
   if (!exact) {
     warningc("exact ignored")
   }
@@ -34,10 +31,11 @@ print.tbl_df <- function(x, ..., n = NULL, width = NULL) {
 #' @export
 `$.tbl_df` <- function(x, i) {
   if (is.character(i) && !(i %in% names(x))) {
-    stopc("Unknown column '", i, "'")
+    warningc("Unknown column '", i, "'")
+    .subset2(x, i, exact = FALSE)
+  } else {
+    .subset2(x, i)
   }
-
-  .subset2(x, i)
 }
 
 #' @export

diff --git a/tests/testthat/test-tbl-df.R b/tests/testthat/test-tbl-df.R
@@ -110,10 +110,10 @@ test_that("can use recursive indexing with [[", {
   expect_equal(foo[[c("x", "y")]], 1:3)
 })
 
-test_that("[[ throws error if name doesn't exist", {
+test_that("[[ returns NULL if name doesn't exist", {
   df <- data_frame(x = 1)
-  expect_error(df[["y"]], "Unknown column 'y'")
-  expect_error(df[[1, "y"]], "Unknown column 'y'")
+  expect_null(df[["y"]])
+  expect_null(df[[1, "y"]])
 })
 
 test_that("can use two-dimensional indexing with [[", {
@@ -126,13 +126,16 @@ test_that("can use two-dimensional indexing with [[", {
 
 test_that("$ throws error if name doesn't exist", {
   df <- data_frame(x = 1)
-  expect_error(df$y, "Unknown column 'y'")
+  expect_warning(expect_null(df$y),
+                 "Unknown column 'y'")
 })
 
 test_that("$ doesn't do partial matching", {
   df <- data_frame(partial = 1)
-  expect_error(df$p, "Unknown column 'p'")
-  expect_error(df$part, "Unknown column 'part'")
+  expect_warning(expect_identical(df$p, 1),
+                 "Unknown column 'p'")
+  expect_warning(expect_identical(df$part, 1),
+                 "Unknown column 'part'")
   expect_error(df$partial, NA)
 })