Type Alias CmcdTransformRequest<C>

The media request handed to a report transform, as a read-only view.

The request is context only. A transform reads it to decide what to do with the report and must not mutate it: it belongs to the caller, which may still be using it. Every member is readonly, and customData is readonly at every depth, so nested values cannot be written either.

By default customData values are unknown rather than any, because the library cannot know the player's shape. Narrow with a cast or bracket access to read player-specific fields:

transform: (data, request) =>
	request?.customData?.['requestType'] === 'segment' ? data : null
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Supply C to describe the player's own customData instead and those reads become typed dot access. Annotating one transform is enough: the reporter infers C for every other transform in the same configuration.

type PlayerData = { requestType: string; };

const segmentsOnly: CmcdEventReportTransform<PlayerData> = (data, request) =>
	request?.customData?.requestType === 'segment' ? data : null
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C is applied through DeepReadonly, so describing a nested shape does not trade the no-mutation guarantee for typed reads.

Two limits are worth knowing. A mutable body such as FormData or URLSearchParams has mutating methods of its own that no type can block, and JavaScript callers get no enforcement at all. Mutating the request through either route is unsupported, and the outgoing report may reflect it.