Fix event filter empty label value arrays to return no results (#18810)

Co-authored-by: Claude <[email protected]>

Author: chrisguidry

AGENTS.md

@@ -68,5 +68,6 @@ prefect config view            # Inspect configuration
 
 - GitHub issues are used for tracking issues (use the `gh` cli)
 - Pre-commit hooks required (never use `--no-verify`)
+- There are some slower pre-push hooks that may modify files on `git push`; when that happens, run `git commit --amend` to bring those into the prior commit (never use `--amend` in any other situation unless asked)
 - Dependencies: updates to client-side deps in `@pyproject.toml` require parallel changes ing `@client/pyproject.toml`
-- AGENTS.md always symlinked to CLAUDE.md
+- AGENTS.md always symlinked to CLAUDE.md

docs/v3/api-ref/python/prefect-server-events-filters.mdx

@@ -257,11 +257,11 @@ includes(self, event: Event) -> bool
 Does the given event match the criteria of this filter?
 
 
-### `EventRelatedFilter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L387" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+### `EventRelatedFilter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L392" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 **Methods:**
 
-#### `build_where_clauses` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L405" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+#### `build_where_clauses` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L410" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 ```python
 build_where_clauses(self, db: PrefectDBInterface) -> Sequence['ColumnExpressionArgument[bool]']
@@ -291,11 +291,11 @@ includes(self, event: Event) -> bool
 Does the given event match the criteria of this filter?
 
 
-### `EventAnyResourceFilter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L486" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+### `EventAnyResourceFilter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L496" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 **Methods:**
 
-#### `build_where_clauses` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L523" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+#### `build_where_clauses` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L533" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 ```python
 build_where_clauses(self, db: PrefectDBInterface) -> Sequence['ColumnExpressionArgument[bool]']
@@ -316,7 +316,7 @@ Would the given filter exclude this event?
 get_filters(self) -> list['EventDataFilter']
 ```
 
-#### `includes` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L501" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+#### `includes` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L511" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 ```python
 includes(self, event: Event) -> bool
@@ -331,11 +331,11 @@ includes(self, event: Event) -> bool
 Does the given event match the criteria of this filter?
 
 
-### `EventIDFilter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L591" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+### `EventIDFilter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L606" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 **Methods:**
 
-#### `build_where_clauses` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L604" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+#### `build_where_clauses` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L619" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 ```python
 build_where_clauses(self, db: PrefectDBInterface) -> Sequence['ColumnExpressionArgument[bool]']
@@ -356,7 +356,7 @@ Would the given filter exclude this event?
 get_filters(self) -> list['EventDataFilter']
 ```
 
-#### `includes` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L596" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+#### `includes` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L611" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 ```python
 includes(self, event: Event) -> bool
@@ -371,7 +371,7 @@ includes(self, event: Event) -> bool
 Does the given event match the criteria of this filter?
 
 
-### `EventOrder` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L615" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+### `EventOrder` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L630" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 **Methods:**
 
@@ -384,11 +384,11 @@ auto() -> str
 Exposes `enum.auto()` to avoid requiring a second import to use `AutoEnum`
 
 
-### `EventFilter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L620" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+### `EventFilter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L635" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 **Methods:**
 
-#### `build_where_clauses` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L653" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+#### `build_where_clauses` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L668" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 ```python
 build_where_clauses(self, db: PrefectDBInterface) -> Sequence['ColumnExpressionArgument[bool]']
@@ -418,7 +418,7 @@ includes(self, event: Event) -> bool
 Does the given event match the criteria of this filter?
 
 
-#### `logical_limit` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L670" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+#### `logical_limit` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/filters.py#L685" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
 
 ```python
 logical_limit(self) -> int

src/prefect/server/events/filters.py

@@ -359,6 +359,11 @@ def build_where_clauses(
 
             if labels:
                 for _, (label, values) in enumerate(labels.items()):
+                    # Empty label value arrays should match nothing
+                    if not values:
+                        label_filters.append(sa.false())
+                        continue
+
                     label_ops = LabelOperations(values)
 
                     label_column = db.EventResource.resource[label].astext
@@ -451,6 +456,11 @@ def build_where_clauses(
 
             if labels:
                 for _, (label, values) in enumerate(labels.items()):
+                    # Empty label value arrays should match nothing
+                    if not values:
+                        label_filters.append(sa.false())
+                        continue
+
                     label_ops = LabelOperations(values)
 
                     label_column = db.EventResource.resource[label].astext
@@ -563,6 +573,11 @@ def build_where_clauses(
 
             if labels:
                 for _, (label, values) in enumerate(labels.items()):
+                    # Empty label value arrays should match nothing
+                    if not values:
+                        label_filters.append(sa.false())
+                        continue
+
                     label_ops = LabelOperations(values)
 
                     label_column = db.EventResource.resource[label].astext

tests/events/server/test_events_queries.py

@@ -1502,3 +1502,59 @@ async def test_event_dates_always_have_timezones(
 async def test_corrupted_page_tokens_are_treated_as_noops(busted_token: str):
     with pytest.raises(ValueError):
         from_page_token(busted_token)
+
+
+async def test_resource_filter_empty_label_values(
+    events_query_session: AsyncSession,
+    full_occurred_range: EventOccurredFilter,
+) -> None:
+    """Test that resource labels with empty values array return no results."""
+
+    filter = EventFilter(
+        occurred=full_occurred_range,
+        resource=EventResourceFilter(labels={"hello": []}),  # Empty values = no matches
+    )
+
+    events, count, _ = await query_events(session=events_query_session, filter=filter)
+
+    # Empty label values should match nothing
+    assert count == 0
+    assert events == []
+
+
+async def test_related_filter_empty_label_values(
+    events_query_session: AsyncSession,
+    full_occurred_range: EventOccurredFilter,
+) -> None:
+    """Test that related resource labels with empty values array return no results."""
+
+    filter = EventFilter(
+        occurred=full_occurred_range,
+        related=EventRelatedFilter(labels={"hello": []}),  # Empty values = no matches
+    )
+
+    events, count, _ = await query_events(session=events_query_session, filter=filter)
+
+    # Empty label values should match nothing
+    assert count == 0
+    assert events == []
+
+
+async def test_any_resource_filter_empty_label_values(
+    events_query_session: AsyncSession,
+    full_occurred_range: EventOccurredFilter,
+) -> None:
+    """Test that any resource labels with empty values array return no results."""
+
+    filter = EventFilter(
+        occurred=full_occurred_range,
+        any_resource=EventAnyResourceFilter(
+            labels={"hello": []}
+        ),  # Empty values = no matches
+    )
+
+    events, count, _ = await query_events(session=events_query_session, filter=filter)
+
+    # Empty label values should match nothing
+    assert count == 0
+    assert events == []