get: copy/download files tracked by Git

dvc/command/get.py

@@ -33,7 +33,7 @@ def run(self):
 
 
 def add_parser(subparsers, parent_parser):
-    GET_HELP = "Download data from DVC repository."
+    GET_HELP = "Download/copy files or directories from DVC repository."
     get_parser = subparsers.add_parser(
         "get",
         parents=[parent_parser],
@@ -44,9 +44,14 @@ def add_parser(subparsers, parent_parser):
     get_parser.add_argument(
         "url", help="URL of Git repository with DVC project to download from."
     )
-    get_parser.add_argument("path", help="Path to data within DVC repository.")
     get_parser.add_argument(
-        "-o", "--out", nargs="?", help="Destination path to put data to."
+        "path", help="Path to a file or directory within a DVC repository."
+    )
+    get_parser.add_argument(
+        "-o",
+        "--out",
+        nargs="?",
+        help="Destination path to copy/download files to.",
     )
     get_parser.add_argument(
         "--rev", nargs="?", help="DVC repository git revision."

dvc/exceptions.py

@@ -268,6 +268,12 @@ def __init__(self, path, cause=None):
         )
 
 
+class PathOutsideRepoError(DvcException):
+    def __init__(self, path, repo):
+        msg = "The path '{}' does not exist in the target repository '{}'."
+        super(PathOutsideRepoError, self).__init__(msg.format(path, repo))
+
+
 class DvcIgnoreInCollectedDirError(DvcException):
     def __init__(self, ignore_dirname):
         super(DvcIgnoreInCollectedDirError, self).__init__(

dvc/repo/get.py

@@ -1,22 +1,39 @@
 import logging
 import os
+import shutil
 
 import shortuuid
 
 from dvc.exceptions import GetDVCFileError
 from dvc.exceptions import NotDvcRepoError
 from dvc.exceptions import OutputNotFoundError
 from dvc.exceptions import UrlNotDvcRepoError
+from dvc.exceptions import PathOutsideRepoError
 from dvc.external_repo import external_repo
 from dvc.path_info import PathInfo
 from dvc.stage import Stage
 from dvc.state import StateNoop
 from dvc.utils import resolve_output
 from dvc.utils.fs import remove
+from dvc.utils.compat import FileNotFoundError
 
 logger = logging.getLogger(__name__)
 
 
+def _copy_git_file(repo, src, dst, repo_url):
+    src_full_path = os.path.join(repo.root_dir, src)
+    dst_full_path = os.path.abspath(dst)
+
+    if os.path.isdir(src_full_path):
+        shutil.copytree(src_full_path, dst_full_path)
+        return
+
+    try:
+        shutil.copy2(src_full_path, dst_full_path)
+    except FileNotFoundError:
+        raise PathOutsideRepoError(src, repo_url)
+
+
 @staticmethod
 def get(url, path, out=None, rev=None):
     out = resolve_output(path, out)
@@ -49,16 +66,31 @@ def get(url, path, out=None, rev=None):
             # the same cache file might be used a few times in a directory.
             repo.cache.local.cache_types = ["reflink", "hardlink", "copy"]
 
-            o = repo.find_out_by_relpath(path)
+            output = None
+            output_error = None
+
+            try:
+                output = repo.find_out_by_relpath(path)
+            except OutputNotFoundError as ex:
+                output_error = ex
+
+            is_git_file = output_error and not os.path.isabs(path)
+            is_not_cached = output and not output.use_cache
+
+            if is_git_file or is_not_cached:
+                _copy_git_file(repo, path, out, url)
+                return
+
+            if output_error:
+                raise OutputNotFoundError(path)
+
             with repo.state:
-                repo.cloud.pull(o.get_used_cache())
-            o.path_info = PathInfo(os.path.abspath(out))
-            with o.repo.state:
-                o.checkout()
+                repo.cloud.pull(output.get_used_cache())
+            output.path_info = PathInfo(os.path.abspath(out))
+            with output.repo.state:
+                output.checkout()
 
     except NotDvcRepoError:
         raise UrlNotDvcRepoError(url)
-    except OutputNotFoundError:
-        raise OutputNotFoundError(path)
     finally:
         remove(tmp_dir)

tests/func/test_get.py

@@ -9,10 +9,13 @@
 from dvc.config import Config
 from dvc.exceptions import GetDVCFileError
 from dvc.exceptions import UrlNotDvcRepoError
+from dvc.exceptions import OutputNotFoundError
+from dvc.exceptions import PathOutsideRepoError
 from dvc.repo import Repo
 from dvc.system import System
 from dvc.utils import makedirs
 from dvc.utils.compat import fspath
+from dvc.utils import fspath_py35
 from tests.utils import trees_equal
 
 
@@ -38,6 +41,36 @@ def test_get_repo_dir(erepo):
     trees_equal(src, dst)
 
 
+def test_get_regular_file(erepo):
+    src = "some_file"
+    dst = "some_file_imported"
+
+    src_path = os.path.join(erepo.root_dir, src)
+    erepo.create(src_path, "hello")
+    erepo.dvc.scm.add([src_path])
+    erepo.dvc.scm.commit("add a regular file")
+    Repo.get(erepo.root_dir, src, dst)
+
+    assert os.path.exists(dst)
+    assert os.path.isfile(dst)
+    assert filecmp.cmp(src_path, dst, shallow=False)
+
+
+def test_get_regular_dir(erepo):
+    src = "some_directory"
+    dst = "some_directory_imported"
+
+    src_file_path = os.path.join(erepo.root_dir, src, "file.txt")
+    erepo.create(src_file_path, "hello")
+    erepo.dvc.scm.add([src_file_path])
+    erepo.dvc.scm.commit("add a regular dir")
+    Repo.get(erepo.root_dir, src, dst)
+
+    assert os.path.exists(dst)
+    assert os.path.isdir(dst)
+    trees_equal(os.path.join(erepo.root_dir, src), dst)
+
+
 def test_cache_type_is_properly_overridden(erepo):
     erepo.dvc.config.set(
         Config.SECTION_CACHE, Config.SECTION_CACHE_TYPE, "symlink"
@@ -77,6 +110,51 @@ def test_get_a_dvc_file(erepo):
         Repo.get(erepo.root_dir, "some_file.dvc")
 
 
+# https://github.com/iterative/dvc/pull/2837#discussion_r352123053
+def test_get_full_dvc_path(erepo):
+    external_data_dir = erepo.mkdtemp()
+    external_data = os.path.join(external_data_dir, "ext_data")
+    with open(external_data, "w+") as fobj:
+        fobj.write("ext_data")
+
+    cur_dir = os.getcwd()
+    os.chdir(erepo.root_dir)
+    erepo.dvc.add(external_data)
+    erepo.dvc.scm.add(["ext_data.dvc"])
+    erepo.dvc.scm.commit("add external data")
+    os.chdir(cur_dir)
+
+    Repo.get(erepo.root_dir, external_data, "ext_data_imported")
+    assert os.path.isfile("ext_data_imported")
+    assert filecmp.cmp(external_data, "ext_data_imported", shallow=False)
+
+
+def test_non_cached_output(tmp_path, erepo):
+    os.chdir(erepo.root_dir)
+    erepo.dvc.run(
+        outs_no_cache=["non_cached_file"], cmd="echo hello > non_cached_file"
+    )
+    erepo.dvc.scm.add(["non_cached_file", "non_cached_file.dvc"])
+    erepo.dvc.scm.commit("add non-cached output")
+    os.chdir(fspath_py35(tmp_path))
+    Repo.get(erepo.root_dir, "non_cached_file")
+
+    src = os.path.join(erepo.root_dir, "non_cached_file")
+    assert os.path.isfile("non_cached_file")
+    assert filecmp.cmp(src, "non_cached_file", shallow=False)
+
+
+# https://github.com/iterative/dvc/pull/2837#discussion_r352123053
+def test_fails_with_files_outside_repo(erepo):
+    with pytest.raises(OutputNotFoundError):
+        Repo.get(erepo.root_dir, "/root/")
+
+
+def test_fails_with_non_existing_files(erepo):
+    with pytest.raises(PathOutsideRepoError):
+        Repo.get(erepo.root_dir, "file_does_not_exist")
+
+
 @pytest.mark.parametrize("dname", [".", "dir", "dir/subdir"])
 def test_get_to_dir(dname, erepo):
     src = erepo.FOO