Function injectJoinedSchemas

backend/api/v1/document_masking.go:810–843

injectJoinedSchemas adds array-of-objects schemas for each $lookup/$graphLookup join into the source objectSchema so masking covers the joined field. The as field holds an array of joined documents, so the injected schema is ARRAY{item: joinedSchema}. If the source schema has no StructKind or the jo

(objectSchema *storepb.ObjectSchema, joins []joinedSchema)

// The as field holds an array of joined documents, so the injected schema is ARRAY{item: joinedSchema}.
// If the source schema has no StructKind or the joined collection has no schema, the join is skipped silently.
func injectJoinedSchemas(objectSchema *storepb.ObjectSchema, joins []joinedSchema) *storepb.ObjectSchema {
	if objectSchema == nil || len(joins) == 0 {
		return objectSchema
	}
	structKind := objectSchema.GetStructKind()
	if structKind == nil {
		return objectSchema
	}

	// Clone properties map so we don't mutate the cached schema.
	props := make(map[string]*storepb.ObjectSchema, len(structKind.Properties)+len(joins))
	maps.Copy(props, structKind.Properties)
	for _, j := range joins {
		if j.schema == nil {
			continue
		}
		props[j.asField] = &storepb.ObjectSchema{
			Type: storepb.ObjectSchema_ARRAY,
			Kind: &storepb.ObjectSchema_ArrayKind_{
				ArrayKind: &storepb.ObjectSchema_ArrayKind{
					Kind: j.schema,
				},
			},
		}
	}
	return &storepb.ObjectSchema{
		Type: storepb.ObjectSchema_OBJECT,
		Kind: &storepb.ObjectSchema_StructKind_{
			StructKind: &storepb.ObjectSchema_StructKind{
				Properties: props,
			},
		},
	}
}

// joinedSchema pairs an as-field name with its resolved ObjectSchema.
type joinedSchema struct {