fix(grouping): Add default value for fingerprint rule text (#81076)

In #80935, we switched from calculating fingerprinting rule text in the `expose_fingerprint_dict` helper to reading it from the fingerprint info, since as of #79231 we store it there. This works fine for new events, but this code also runs when someone opens the grouping info section of the issue details page, and if they do that on an event from before we started storing the rule text, it results in a key error.

This fixes that by partially undoing the change made in #80935 - it doesn't switch back to always re-calculating the the rule text, but does fall back to doing so when it's not found in the stored data.

Author: lobsterkatie

src/sentry/grouping/variants.py

@@ -2,6 +2,7 @@
 
 from typing import TypedDict
 
+from sentry.grouping.fingerprinting import FingerprintRule
 from sentry.grouping.utils import hash_from_values, is_default_fingerprint_var
 from sentry.types.misc import KeyedList
 
@@ -147,7 +148,11 @@ def expose_fingerprint_dict(values, info):
 
     matched_rule = info.get("matched_rule")
     if matched_rule:
-        rv["matched_rule"] = matched_rule["text"]
+        # TODO: Before late October 2024, we didn't store the rule text along with the matched rule,
+        # meaning there are still events out there whose `_fingerprint_info` entry doesn't have it.
+        # Once those events have aged out (in February or so), we can remove the default value here
+        # and the `test_old_event_with_no_fingerprint_rule_text` test in `test_variants.py`.
+        rv["matched_rule"] = matched_rule.get("text", FingerprintRule.from_json(matched_rule).text)
 
     return rv
 

tests/sentry/grouping/test_variants.py

@@ -4,6 +4,7 @@
 
 from sentry.eventstore.models import Event
 from sentry.grouping.strategies.configurations import CONFIGURATIONS
+from sentry.grouping.variants import CustomFingerprintVariant, expose_fingerprint_dict
 from sentry.models.project import Project
 from sentry.projectoptions.defaults import DEFAULT_GROUPING_CONFIG
 from sentry.testutils.pytest.fixtures import InstaSnapshotter, django_db_all
@@ -97,3 +98,22 @@ def _assert_and_snapshot_results(
             __file__, input_file, "test_event_hash_variant", config_name
         ),
     )
+
+
+# TODO: This can be deleted after Jan 2025, when affected events have aged out
+def test_old_event_with_no_fingerprint_rule_text():
+    variant = CustomFingerprintVariant(
+        ["dogs are great"],
+        {
+            "matched_rule": {
+                "attributes": {},
+                "fingerprint": ["dogs are great"],
+                "matchers": [["message", "*dogs*"]],
+                # newer events have a `text` entry here
+            }
+        },
+    )
+    assert expose_fingerprint_dict(variant.values, variant.info) == {
+        "values": ["dogs are great"],
+        "matched_rule": 'message:"*dogs*" -> "dogs are great"',
+    }