Fix #310

NAMESPACE

@@ -223,6 +223,11 @@ export(tar_destroy)
 export(tar_dir)
 export(tar_edit)
 export(tar_envir)
+export(tar_exist_meta)
+export(tar_exist_objects)
+export(tar_exist_process)
+export(tar_exist_progress)
+export(tar_exist_script)
 export(tar_glimpse)
 export(tar_group)
 export(tar_helper)

NEWS.md

@@ -11,6 +11,7 @@
 * Record info on the main process (PID, R version, `targets` version) in `_targets/meta/process` and write new functions `tar_process()` and `tar_pid()` to retrieve the data (#291, #292).
 * Add a new `targets_only` argument to `tar_meta()`.
 * Add new functions `tar_helper()` and `tar_helper_raw()` to write general-purpose R scripts, using tidy evaluation for as a template mechanism (#290, #291, #292, #306).
+* Export functions to check the existence of various pieces of local storage: `tar_exist_meta()`, `tar_exist_objects()`, `tar_exist_progress()`, `tar_exist_progress()`, `tar_exist_script()` (#310).
 
 ## Enhancements
 

R/tar_exist_meta.R

@@ -0,0 +1,12 @@
+#' @title Check if target metadata exists.
+#' @export
+#' @description Check if the target metadata file `_targets/meta/meta`
+#'   exists for the current project.
+#' @details To learn more about local storage in `targets`, visit
+#'   <https://books.ropensci.org/targets/files.html#internal-files>.
+#' @return Logical of length 1, whether the current project's metadata exists.
+#' @examples
+#' tar_exist_meta()
+tar_exist_meta <- function() {
+  file.exists(path_meta())
+}

R/tar_exist_objects.R

@@ -0,0 +1,16 @@
+#' @title Check if local output data exists for one or more targets.
+#' @export
+#' @description Check if the local data files exist in
+#'   `_targets/objects/` for one or more targets.
+#' @details To learn more about local storage in `targets`, visit
+#'   <https://books.ropensci.org/targets/files.html#internal-files>.
+#' @return Logical of length `length(names)`, whether
+#'   each given target has an existing file in `_targets/objects/`
+#'   for the current project.
+#' @param names Character vector of target names.
+#' @examples
+#' tar_exist_objects(c("target1", "target2"))
+tar_exist_objects <- function(names) {
+  assert_chr(names, "names must be a character vector.")
+  file.exists(path_objects(names))
+}

R/tar_exist_process.R

@@ -0,0 +1,12 @@
+#' @title Check if process metadata exists.
+#' @export
+#' @description Check if the process metadata file `_targets/meta/process`
+#'   exists for the current project.
+#' @details To learn more about local storage in `targets`, visit
+#'   <https://books.ropensci.org/targets/files.html#internal-files>.
+#' @return Logical of length 1, whether the current project's metadata exists.
+#' @examples
+#' tar_exist_process()
+tar_exist_process <- function() {
+  file.exists(path_process())
+}

R/tar_exist_progress.R

@@ -0,0 +1,12 @@
+#' @title Check if progress metadata exists.
+#' @export
+#' @description Check if the progress metadata file `_targets/meta/progress`
+#'   exists for the current project.
+#' @details To learn more about local storage in `targets`, visit
+#'   <https://books.ropensci.org/targets/files.html#internal-files>.
+#' @return Logical of length 1, whether the current project's metadata exists.
+#' @examples
+#' tar_exist_progress()
+tar_exist_progress <- function() {
+  file.exists(path_progress())
+}

R/tar_exist_script.R

@@ -0,0 +1,10 @@
+#' @title Check if the target script exists.
+#' @export
+#' @description Check if the `_targets.R` file of the current project exists.
+#'   exists for the current project.
+#' @return Logical of length 1, whether the current project's metadata exists.
+#' @examples
+#' tar_exist_script()
+tar_exist_script <- function() {
+  file.exists(path_script())
+}

_pkgdown.yml

@@ -86,6 +86,13 @@ reference:
   - '`tar_progress_branches`'
   - '`tar_sitrep`'
   - '`tar_workspaces`'
+- title: Existence
+  contents:
+  - '`tar_exist_meta`'
+  - '`tar_exist_objects`'
+  - '`tar_exist_process`'
+  - '`tar_exist_progress`'
+  - '`tar_exist_script`'
 - title: Branching
   contents:
   - '`tar_branches`'

tests/testthat/test-tar_exist_meta.R

@@ -0,0 +1,6 @@
+tar_test("tar_exist_meta()", {
+  expect_false(tar_exist_meta())
+  dir_create(dirname(path_meta()))
+  file.create(path_meta())
+  expect_true(tar_exist_meta())
+})

tests/testthat/test-tar_exist_objects.R

@@ -0,0 +1,5 @@
+tar_test("tar_exist_objects()", {
+  dir_create(dirname(path_objects("x")))
+  file.create(path_objects("x"))
+  expect_equal(tar_exist_objects(c("y", "x")), c(FALSE, TRUE))
+})

tests/testthat/test-tar_exist_process.R

@@ -0,0 +1,6 @@
+tar_test("tar_exist_process()", {
+  expect_false(tar_exist_process())
+  dir_create(dirname(path_process()))
+  file.create(path_process())
+  expect_true(tar_exist_process())
+})

tests/testthat/test-tar_exist_progress.R

@@ -0,0 +1,6 @@
+tar_test("tar_exist_progress()", {
+  expect_false(tar_exist_progress())
+  dir_create(dirname(path_progress()))
+  file.create(path_progress())
+  expect_true(tar_exist_progress())
+})

tests/testthat/test-tar_exist_script.R

@@ -0,0 +1,5 @@
+tar_test("tar_exist_script()", {
+  expect_false(tar_exist_script())
+  tar_script()
+  expect_true(tar_exist_script())
+})