fix: parse JSON-string url.query_params in FormatAttributes#520
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fix: parse JSON-string url.query_params in FormatAttributes#520
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Adds a small allowlist in hlog.FormatAttributes so JSON-encoded string values for known keys (currently just url.query_params) are parsed and flattened into nested attributes (url.query_params.<k>) before storage. The JS SDK now emits these as native nested OTel attributes (#517), so this is the backend-ingest complement that handles older SDK versions and other clients (Node, Python, .NET, Android, Java) still sending the JSON-string form. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
mayberryzane
approved these changes
May 6, 2026
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Summary
hlog.FormatAttributessees a JSON-encoded string value for an allowlisted key, parse it and flatten into nested attributes (e.g.url.query_params.foo).url.query_params. Every entry adds permanent keys to the ClickHouseMap(LowCardinality(String), String)dictionary, so it stays small.url.query_paramsas a JSON blob; this lets those clients also produce structured, queryable output without an SDK update.Test plan
go test ./log/... -run TestFormatAttributes -v(8 cases: allowlisted JSON expansion, allowlisted non-JSON pass-through, allowlisted malformed JSON pass-through, leading-whitespace tolerance, nested-object expansion, scalar types unaffected, non-allowlisted key not parsed)go vet ./log/...gofmt -lcleanobservability/backend) builds clean against this branch via go.work🤖 Generated with Claude Code
Note
Medium Risk
Changes log attribute normalization to parse and flatten JSON-encoded strings for allowlisted keys, which can alter emitted attribute keys and increase cardinality in storage. Scoped by an explicit allowlist and guarded parsing, but impacts ingestion/query behavior for those fields.
Overview
FormatAttributesnow detects JSON-looking string values for an explicit allowlist of keys (starting withurl.query_params), parses them, and flattens the result into dotted child attributes (e.g.url.query_params.foo).Adds
looksLikeJSONObjectOrArrayas a cheap pre-check and introduces tests covering allowlisted expansion, non-allowlisted pass-through, malformed/non-JSON handling, whitespace tolerance, nested objects, and unchanged behavior for other scalar/map types.Reviewed by Cursor Bugbot for commit 816822d. Bugbot is set up for automated code reviews on this repo. Configure here.