GODRIVER-3470 Correct BSON unmarshaling logic for null values #1924
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API Change ReportNo changes found! |
prestonvasquez
added
priority-1-high
matthewdale
reviewed
Feb 3, 2025
bson/unmarshaling_cases_test.go
Outdated
| PtrTracker *unmarshalCallTracker `bson:"ptr_tracker"` | ||
| } | ||
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| func (ms *unmarshalCallTracker) UnmarshalBSONValue(bsontype.Type, []byte) error { |
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Should we also test this behavior for UnmarshalBSON?
matthewdale
approved these changes
Feb 6, 2025
| // directly set to nil here. Since the pointer is being replaced with nil, | ||
| // there is no opportunity (or reason) for the custom UnmarshalBSONValue logic | ||
| // to be called. | ||
| if vr.Type() == bsontype.Null && val.Kind() == reflect.Ptr { |
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There is a similar block in UnmarshalerDecodeValue after the value is read into a []byte:
if val.Kind() == reflect.Ptr && len(src) == 0 {
val.Set(reflect.Zero(val.Type()))
return nil
}Can we use the same condition in both methods? Or are they distinct scenarios?
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GODRIVER-3470
Summary
Ensure UnmarshalBSONValue is bypassed and the Go pointer is set to nil ONLY when the Go type is a pointer and the BSON value is null.
Background & Motivation
PR #1903 introduced logic where UnmarshalBSONValue() is not called for bson.TypeNull, which breaks applications that rely on this behavior for initializing fields.