[duplicate-code] Duplicate Code Pattern: Manual JSON response writing bypassing httputil.WriteJSONResponse in proxy/handler.go

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Part of duplicate code analysis: #3309

Summary

internal/proxy/handler.go contains two locations where JSON HTTP responses are written by manually setting the Content-Type header, calling w.WriteHeader, and then w.Write. The project already provides httputil.WriteJSONResponse (in internal/httputil/httputil.go) that encapsulates exactly this 3-line pattern, but these two sites bypass it.

Duplication Details

Pattern: Manual Content-Type: application/json + WriteHeader + Write instead of httputil.WriteJSONResponse

• Severity: Low
• Occurrences: 2 (≈6 lines)
• Locations:
  • internal/proxy/handler.go line 328–331 (inside DIFC-filtered GraphQL response path)
  • internal/proxy/handler.go line 365–367 (inside writeEmptyResponse)
• Code Sample:

// handler.go:328-331
copyResponseHeaders(w, resp)
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(resp.StatusCode)
w.Write(filteredJSON)

// handler.go:364-367
func (h *proxyHandler) writeEmptyResponse(w http.ResponseWriter, resp *http.Response, originalData interface{}) {
    copyResponseHeaders(w, resp)
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(resp.StatusCode)
    ...
    w.Write([]byte(empty))
}

• Existing helper (internal/httputil/httputil.go):

func WriteJSONResponse(w http.ResponseWriter, statusCode int, body interface{}) {
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(statusCode)
    json.NewEncoder(w).Encode(body)
}

Note: httputil.WriteJSONResponse is already used correctly elsewhere in the same file (lines 28, 51, 83).

Impact Analysis

• Maintainability: If the JSON response format or headers change (e.g. adding X-Content-Type-Options), the two manual sites would be missed.
• Bug Risk: httputil.WriteJSONResponse uses json.NewEncoder(w).Encode(body) which adds a trailing newline and handles encoding; the manual sites use raw w.Write([]byte) which skips encoding safety.
• Consistency: Inconsistent use of the helper within the same file.

Refactoring Recommendations

1. Site 1 (handler.go line 328–331): Replace the manual 3-line block with a call to httputil.WriteJSONResponse(w, resp.StatusCode, json.RawMessage(filteredJSON)) after copyResponseHeaders. Note: copyResponseHeaders must still be called first to preserve upstream response headers.

2. Site 2 (writeEmptyResponse): The empty-body case writes a raw string ("[]", "{}", {"data":null}), so httputil.WriteJSONResponse fits directly: httputil.WriteJSONResponse(w, resp.StatusCode, json.RawMessage(empty)).

   Estimated effort: 30 minutes. Purely mechanical substitution with no behavioural change.

Implementation Checklist

• Replace manual JSON response writes at handler.go:328–331 and handler.go:364–383
• Verify copyResponseHeaders is still called before the helper (header order matters)
• Run make test to confirm proxy handler tests pass
• Run make agent-finished

Parent Issue

See parent analysis report: #3309
Related to #3309

Generated by Duplicate Code Detector · ● 2.2M · ◷

• expires on Apr 14, 2026, 6:05 AM UTC