FetchNext

FetchNext

FetchNext is a generic term in software development describing a function, method, or command that retrieves the next unit of data from a source. It is commonly used in three contexts: iteration, pagination, and streaming.

In iteration, FetchNext advances the internal cursor of an iterator and returns the next item, signaling end of data when there is none. In pagination, FetchNext requests the next page of results from a data source, often using a continuation token or cursor. In streaming, FetchNext pulls the next data chunk from a live feed or buffer, coordinating with backpressure mechanisms.

Usage: In many languages, FetchNext is invoked in a loop until a completion condition is reached. In asynchronous or non-blocking APIs, the call may return a promise or future that resolves to the next item or a null/empty value when finished. The exact return type depends on the design: Item, Page, or Chunk.

Implementation notes: FetchNext can be implemented as part of an iterator interface, a streaming API, or a pagination client. Designers should document end-of-data behavior, error handling, and whether calls block, suspend, or throw on lack of data. Handling empty sources and repeated calls at the end should be defined to avoid ambiguous results.

See also: Next, GetNext, Iterator protocol, Pagination, Cursor, Backpressure.