tar_git_snapshot {gittargets}

Snapshot the data repository (Git).

Description

Snapshot the Git data repository of a targets project.

Usage

tar_git_snapshot(
  message = NULL,
  ref = "HEAD",
  code = getwd(),
  script = targets::tar_config_get("script"),
  store = targets::tar_config_get("store"),
  stash_gitignore = TRUE,
  reporter = targets::tar_config_get("reporter_outdated"),
  envir = parent.frame(),
  callr_function = callr::r,
  callr_arguments = NULL,
  status = interactive(),
  force = FALSE,
  pack_refs = TRUE,
  verbose = TRUE
)

Arguments

message

Optional Git commit message of the data snapshot. If NULL, then the message is the Git commit message of the matching code commit.

ref

Character of length 1, reference (branch name, Git SHA1 hash, etc.) of the code commit that will map to the new data snapshot. Defaults to the commit checked out right now.

code

Character of length 1, directory path to the code repository, usually the root of the targets project.

script

Character of length 1, path to the target script file. Defaults to tar_config_get("script"), which in turn defaults to ⁠_targets.R⁠. When you set this argument, the value of tar_config_get("script") is temporarily changed for the current function call. See tar_script(), tar_config_get(), and tar_config_set() for details about the target script file and how to set it persistently for a project.

store

Character of length 1, path to the data store of the pipeline. If NULL, the store setting is left unchanged in the YAML configuration file (default: ⁠_targets.yaml⁠). Usually, the data store lives at ⁠_targets⁠. Set store to a custom directory to specify a path other than ⁠_targets/⁠. The path need not exist before the pipeline begins, and it need not end with "_targets", but it must be writeable. For optimal performance, choose a storage location with fast read/write access. If the argument NULL, the setting is not modified. Use tar_config_unset() to delete a setting.

stash_gitignore

Logical of length 1, whether to temporarily stash the .gitignore file of the data store. See the "Stashing .gitignore" section for details.

reporter

Character of length 1, name of the reporter to user. Controls how messages are printed as targets are checked. Choices:

• "silent": print nothing.

• "forecast": print running totals of the checked and outdated targets found so far.

envir

An environment, where to run the target R script (default: ⁠_targets.R⁠) if callr_function is NULL. Ignored if callr_function is anything other than NULL. callr_function should only be NULL for debugging and testing purposes, not for serious runs of a pipeline, etc.

The envir argument of tar_make() and related functions always overrides the current value of tar_option_get("envir") in the current R session just before running the target script file, so whenever you need to set an alternative envir, you should always set it with tar_option_set() from within the target script file. In other words, if you call tar_option_set(envir = envir1) in an interactive session and then tar_make(envir = envir2, callr_function = NULL), then envir2 will be used.

callr_function

A function from callr to start a fresh clean R process to do the work. Set to NULL to run in the current session instead of an external process (but restart your R session just before you do in order to clear debris out of the global environment). callr_function needs to be NULL for interactive debugging, e.g. tar_option_set(debug = "your_target"). However, callr_function should not be NULL for serious reproducible work.

callr_arguments

A list of arguments to callr_function.

status

Logical of length 1, whether to print the project status with tar_git_status() and ask whether a snapshot should be created.

force

Logical of length 1. Force checkout the data branch of an existing data snapshot of the current code commit?

pack_refs

Logical of length 1, whether to run ⁠git pack-refs --all⁠ in the data store after taking the snapshot. Packing references improves efficiency when the number of snapshots is large. Learn more at https://git-scm.com/docs/git-pack-refs.

verbose

Logical of length 1, whether to print R console messages confirming that a snapshot was created.

Details

A Git-backed gittargets data snapshot is a special kind of Git commit. Every data commit is part of a branch specific to the current code commit. That way, when you switch branches or commits in the code, tar_git_checkout() checks out the latest data snapshot that matches the code in your workspace. That way, your targets can stay up to date even as you transition among multiple branches.

Stashing .gitignore

The targets package writes a .gitignore file to new data stores in order to prevent accidental commits to the code Git repository. Unfortunately, for gittargets, this automatic .gitignore file interferes with proper data versioning. So by default, gittargets temporarily stashes it to a hidden file called .gittargets_gitignore inside the data store. If your R program crashes while the stash is active, you can simply move it manually back to .gitignore or run tar_git_status_data() to restore the stash automatically if no .gitignore already exists.

See Also

Other git: tar_git_checkout(), tar_git_init(), tar_git_log(), tar_git_ok(), tar_git_status_code(), tar_git_status_data(), tar_git_status_targets(), tar_git_status()

Examples

if (Sys.getenv("TAR_EXAMPLES") == "true" && tar_git_ok(verbose = FALSE)) {
targets::tar_dir({ # Containing code does not modify the user's filespace.
targets::tar_script(tar_target(data, 1))
targets::tar_make()
gert::git_init()
gert::git_add("_targets.R")
gert::git_commit("First commit")
tar_git_init()
tar_git_snapshot(status = FALSE)
})
}