feat(go): enforce required field presence in UnmarshalJSON - #6495
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Go's encoding/json performs case-insensitive field matching during Unmarshal. This causes data corruption when a customer record has a property whose name differs from a reserved field only by casing (e.g. 'ObjectID' vs 'objectID'): - If the customer's property is a string, it silently overwrites the reserved field value (data loss) - If it is a non-string type, Unmarshal fails with a type error (crash) Fix: rewrite the UnmarshalJSON template for models with additionalProperties to parse into a raw map[string]json.RawMessage first, then extract known fields by exact (case-sensitive) key match. Remaining keys are preserved as additional properties with their original casing and types. This affects all Go models with additionalProperties: Hit, RecommendHit, composition Hit, and others. Requires regeneration: yarn cli generate go
The type alias was only needed by the old UnmarshalJSON approach that used json.Unmarshal into the alias to avoid recursive unmarshalling. The new raw-map-based UnmarshalJSON no longer needs it.
Required fields now return an error when absent from the JSON payload instead of silently accepting the zero value. This aligns Go with Python, Swift, Kotlin, Dart, and Scala which all hard-fail on missing required fields.
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✔️ Code generated!
📊 Benchmark resultsBenchmarks performed on the method using a mock server, the results might not reflect the real-world performance.
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Context
Stacked on top of #6494 (case-sensitive JSON key matching fix).
Problem
Go's
UnmarshalJSONfor models withadditionalPropertiessilently accepts missing required fields, leaving them at their zero value (e.g.""forobjectID). This is inconsistent with 5 of our other client languages.Current behavior across languages
ValidationErrorDecodingErrorthrownNoSuchElementExceptionnullnilundefined"",0, etc.)Solution
In the
UnmarshalJSONtemplate, required fields now return an error when their exact JSON key is absent:Optional fields remain unchanged — missing keys are silently accepted.
Affected models
~11 models with
additionalProperties+ required fields, including:search/Hit,composition/Hit,recommend/RecommendHit(objectID)search/SearchResponse(~35 fields, many required)search/SearchSynonymsResponse(hits,nbHits)search/DictionaryEntry(objectID)ingestion/PushTaskRecords(objectID)Checklist
templates/go/model_simple.mustacheyarn cli generate goyarn cli cts run go