plots/metrics: support show for no repo

dvc/repo/__init__.py

@@ -4,6 +4,7 @@
 from functools import wraps
 
 from funcy import cached_property, cat, first
+from git import InvalidGitRepositoryError
 
 from dvc.config import Config
 from dvc.dvcfile import PIPELINE_FILE, Dvcfile, is_valid_filename
@@ -15,6 +16,8 @@
     OutputNotFoundError,
 )
 from dvc.path_info import PathInfo
+from dvc.scm import Base
+from dvc.scm.base import SCMError
 from dvc.tree.repo import RepoTree
 from dvc.utils.fs import path_isin
 
@@ -80,6 +83,37 @@ class Repo:
     from dvc.repo.status import status
     from dvc.repo.update import update
 
+    def _get_repo_dirs(
+        self,
+        root_dir: str = None,
+        scm: Base = None,
+        rev: str = None,
+        uninitialized: bool = False,
+    ):
+        assert bool(scm) == bool(rev)
+
+        from dvc.scm import SCM
+        from dvc.utils.fs import makedirs
+
+        try:
+            tree = scm.get_tree(rev) if rev else None
+            root_dir = self.find_root(root_dir, tree)
+            dvc_dir = os.path.join(root_dir, self.DVC_DIR)
+            tmp_dir = os.path.join(dvc_dir, "tmp")
+            makedirs(tmp_dir, exist_ok=True)
+
+        except NotDvcRepoError:
+            if not uninitialized:
+                raise
+            try:
+                root_dir = SCM(root_dir or os.curdir).root_dir
+            except (SCMError, InvalidGitRepositoryError):
+                root_dir = SCM(os.curdir, no_scm=True).root_dir
+
+            dvc_dir = None
+            tmp_dir = None
+        return root_dir, dvc_dir, tmp_dir
+
     def __init__(
         self,
         root_dir=None,
@@ -95,24 +129,13 @@ def __init__(
         from dvc.repo.metrics import Metrics
         from dvc.repo.params import Params
         from dvc.repo.plots import Plots
-        from dvc.scm import SCM
         from dvc.stage.cache import StageCache
         from dvc.state import State, StateNoop
         from dvc.tree.local import LocalTree
-        from dvc.utils.fs import makedirs
 
-        try:
-            tree = scm.get_tree(rev) if rev else None
-            self.root_dir = self.find_root(root_dir, tree)
-            self.dvc_dir = os.path.join(self.root_dir, self.DVC_DIR)
-            self.tmp_dir = os.path.join(self.dvc_dir, "tmp")
-            makedirs(self.tmp_dir, exist_ok=True)
-        except NotDvcRepoError:
-            if not uninitialized:
-                raise
-            self.root_dir = SCM(root_dir or os.curdir).root_dir
-            self.dvc_dir = None
-            self.tmp_dir = None
+        self.root_dir, self.dvc_dir, self.tmp_dir = self._get_repo_dirs(
+            root_dir=root_dir, scm=scm, rev=rev, uninitialized=uninitialized
+        )
 
         tree_kwargs = {"use_dvcignore": True, "dvcignore_root": self.root_dir}
         if scm:

dvc/repo/metrics/show.py

@@ -3,6 +3,7 @@
 from dvc.exceptions import NoMetricsError
 from dvc.repo import locked
 from dvc.repo.collect import collect
+from dvc.scm.base import SCMError
 from dvc.tree.repo import RepoTree
 from dvc.utils.serialize import YAMLFileCorruptedError, load_yaml
 
@@ -113,8 +114,10 @@ def show(
     # Hide workspace metrics if they are the same as in the active branch
     try:
         active_branch = repo.scm.active_branch()
-    except TypeError:
-        pass  # Detached head
+    except (TypeError, SCMError):
+        # TypeError - detached head
+        # SCMError - no repo case
+        pass
     else:
         if res.get("workspace") == res.get(active_branch):
             res.pop("workspace", None)

tests/func/metrics/test_show.py

@@ -173,3 +173,11 @@ def test_show_falsey(tmp_dir, dvc):
     assert dvc.metrics.show(targets=["metrics.json"]) == {
         "": {"metrics.json": {"foo": 0, "bar": 0.0}}
     }
+
+
+def test_show_no_repo(tmp_dir):
+    tmp_dir.gen("metrics.json", '{"foo": 0, "bar": 0.0, "baz": {}}')
+
+    dvc = Repo(uninitialized=True)
+
+    dvc.metrics.show(targets=["metrics.json"])

tests/func/plots/test_plots.py

@@ -663,3 +663,15 @@ def test_show_non_plot_and_plot_with_params(
     plot_content.pop("title")
     plot2_content.pop("title")
     assert plot_content == plot2_content
+
+
+def test_show_no_repo(tmp_dir):
+    metric = [
+        {"first_val": 100, "val": 2},
+        {"first_val": 200, "val": 3},
+    ]
+    _write_json(tmp_dir, metric, "metric.json")
+
+    dvc = Repo(uninitialized=True)
+
+    dvc.plots.show(["metric.json"])