Add parse_json template function (#3929)

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Support prescribed labels ([#3848](https://github.com/grafana/oncall/pull/3848))
 - Add status change trigger type to webhooks ([#3920](https://github.com/grafana/oncall/pull/3920))
 - Add `EMAIL_USE_SSL` environment setting by @WoodyWoodsta ([#3911](https://github.com/grafana/oncall/pull/3911))
+- Add `parse_json` Jinja2 template filter by @KarimDarwish ([#3929](https://github.com/grafana/oncall/pull/3929))
 
 ### Fixed
 

docs/sources/configure/jinja2-templating/index.md

@@ -227,3 +227,5 @@ Built-in functions:
   - Usage example: `{{ payload.ruleName | regex_match(".*") }}`
 - `b64decode` - performs a base64 string decode
   - Usage example: `{{ payload.data | b64decode }}`
+- `parse_json` - parses a given json string to an object
+  - Usage example: `{{ (payload.data | b64decode | parse_json).name }}`

engine/common/jinja_templater/filters.py

@@ -68,3 +68,10 @@ def b64decode(value):
         return base64.b64decode(value).decode("utf-8")
     except (ValueError, AttributeError, TypeError):
         return None
+
+
+def parse_json(value):
+    try:
+        return json.loads(value)
+    except (ValueError, AttributeError, TypeError):
+        return None

engine/common/jinja_templater/jinja_template_env.py

@@ -9,6 +9,7 @@ from .filters import (
     datetimeformat_as_timezone,
     iso8601_to_time,
     json_dumps,
+    parse_json,
     regex_match,
     regex_replace,
     regex_search,
@@ -33,3 +34,4 @@ jinja_template_env.filters["regex_match"] = regex_match
 jinja_template_env.filters["regex_search"] = regex_search
 jinja_template_env.filters["json_dumps"] = json_dumps
 jinja_template_env.filters["b64decode"] = b64decode
+jinja_template_env.filters["parse_json"] = parse_json

engine/common/tests/test_apply_jinja_template.py

@@ -187,3 +187,16 @@ def test_apply_jinja_template_to_alert_payload_and_labels(mock_apply_jinja_templ
 )
 def test_templated_value_is_truthy(value, expected):
     assert templated_value_is_truthy(value) == expected
+
+
+def test_apply_jinja_template_parse_json():
+    payload = {"message": base64.b64encode(b'{"name": "test"}').decode("utf-8")}
+    expected_name = "test"
+
+    assert (
+        apply_jinja_template(
+            "{{ (payload.message | b64decode | parse_json).name }}",
+            payload,
+        )
+        == expected_name
+    )