From 42cb5266fa9f5a6ae40221029cef7a54c559a51d Mon Sep 17 00:00:00 2001
From: Beto Dealmeida <roberto@dealmeida.net>
Date: Tue, 8 Jun 2021 18:56:55 -0700
Subject: [PATCH] fix: import metrics with extra (#15047)

* fix: import metrics with extra

* Fix test
---
 superset/datasets/commands/importers/v1/utils.py | 3 ++-
 tests/datasets/commands_tests.py                 | 2 +-
 tests/fixtures/importexport.py                   | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/superset/datasets/commands/importers/v1/utils.py b/superset/datasets/commands/importers/v1/utils.py
index c21c66ff18..6b4dbeb7b8 100644
--- a/superset/datasets/commands/importers/v1/utils.py
+++ b/superset/datasets/commands/importers/v1/utils.py
@@ -98,11 +98,12 @@ def import_dataset(
             except TypeError:
                 logger.info("Unable to encode `%s` field: %s", key, config[key])
     for metric in config.get("metrics", []):
-        if metric.get("extra"):
+        if metric.get("extra") is not None:
             try:
                 metric["extra"] = json.dumps(metric["extra"])
             except TypeError:
                 logger.info("Unable to encode `extra` field: %s", metric["extra"])
+                metric["extra"] = None
 
     # should we delete columns and metrics not present in the current import?
     sync = ["columns", "metrics"] if overwrite else []
diff --git a/tests/datasets/commands_tests.py b/tests/datasets/commands_tests.py
index 4df7365a55..1293a301ff 100644
--- a/tests/datasets/commands_tests.py
+++ b/tests/datasets/commands_tests.py
@@ -328,7 +328,7 @@ class TestImportDatasetsCommand(SupersetTestCase):
         assert metric.expression == "count(1)"
         assert metric.description is None
         assert metric.d3format is None
-        assert metric.extra is None
+        assert metric.extra == "{}"
         assert metric.warning_text is None
 
         assert len(dataset.columns) == 1
diff --git a/tests/fixtures/importexport.py b/tests/fixtures/importexport.py
index 04aaaa3945..951ecf9bb4 100644
--- a/tests/fixtures/importexport.py
+++ b/tests/fixtures/importexport.py
@@ -384,7 +384,7 @@ dataset_config: Dict[str, Any] = {
             "expression": "count(1)",
             "description": None,
             "d3format": None,
-            "extra": None,
+            "extra": {},
             "warning_text": None,
         },
     ],