Declare a parent for lineage

Resolves a parent table against a single project connection and returns a pure-data lineage record. The parent's authoritative data_sha and its source_lineage are read from the parent's own versioned metadata snapshot at {table}/.metadata/{version}.json; a caller cannot supply or override data_sha (there is no data_sha parameter). The returned record retains no live connection and is serializable as plain data.

Usage

datom_parent(conn, table, version)

Arguments

conn

A datom_conn scoped to the parent's project store, from datom_get_conn().

table

Parent table name (single non-empty validated string).

version

Parent version (metadata_sha; single non-empty string).

Value

A list with exactly source, table, version, data_sha, and source_lineage. source is the parent connection's project_name; source_lineage is NULL when the snapshot carries none.

Details

Same-project and cross-project parents are declared identically – the only difference is which connection is passed. source is always derived from the connection's project_name.

Examples

# Offline, self-contained: a bare git repo stands in for GitHub and a
# local directory for object storage.
if (requireNamespace("git2r", quietly = TRUE)) {
  tmp <- tempfile("datom-example-")
  remote <- file.path(tmp, "remote.git")
  dir.create(remote, recursive = TRUE)
  git2r::init(remote, bare = TRUE)

  store <- datom_store(
    data = datom_store_local(file.path(tmp, "storage")),
    github_pat = "example-token", # role selector; a local remote needs none
    data_repo_url = remote,
    validate = FALSE
  )
  datom_init_repo(file.path(tmp, "repo"), "example_project", store)
  conn <- datom_get_conn(file.path(tmp, "repo"), store)

  datom_write(conn, data = datom_example_data("dm"), name = "dm")

  # Resolve a parent declaration to pass to the parents argument of
  # datom_write.
  print(datom_parent(conn, "dm", datom_history(conn, "dm")$version[1]))

  unlink(tmp, recursive = TRUE)
}
#> ℹ Created store directory /tmp/Rtmp0YCcPh/datom-example-1a3183241b7/storage.
#> ✔ Initialized datom repository "example_project" at /tmp/Rtmp0YCcPh/datom-example-1a3183241b7/repo
#> ✔ Wrote "dm" (full): "039f0c3f"
#> $source
#> [1] "example_project"
#> 
#> $table
#> [1] "dm"
#> 
#> $version
#> [1] "039f0c3fc4d639b4977f44e83df863da9535e70df737cc758747bda8bd2d89d8"
#> 
#> $data_sha
#> [1] "71a93ffaa4cdc59750a5d5fbf49bb4ffcd656f00038cae2849958acae622b538"
#> 
#> $source_lineage
#> NULL
#>