[19.1.x][FlightReply] Don't drop FormData entries in decodeReplyFromBusboy#36567
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May 28, 2026
| webpackServerMap = WebpackMock.webpackServerMap; | ||
| ReactServerDOMServer = require('react-server-dom-webpack/server.node'); | ||
| jest.resetModules(); | ||
| ReactServerDOMClient = require('react-server-dom-webpack/client.edge'); |
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Different from the original PR. The Node.js Client didn't have encodeReply before #33474
…Busboy` Fixes a regression from facebook#36425 where referenced `FormData` entries can be dropped by `decodeReplyFromBusboy` when files are interleaved with text fields in the payload. `decodeReplyFromBusboy` queues text fields that arrive while a file is being streamed and flushes them after the last file's `'end'`, working around busboy emitting `'end'` deferred relative to subsequent `'field'` events. With multiple files interleaved with text, this loses the relative order of the affected text entries. The reorder was a long-standing but invisible issue — entries came back in the wrong order but were all present — until facebook#36425 tightened how referenced FormData entries are collected from the backing store to rely on them being contiguous. With that assumption violated, referenced FormDatas can now come back with some entries dropped. The pattern is most easily surfaced through `useActionState` actions that return the submitted `FormData` as part of their state. This replaces the tail-flush with a linked list of pending files. Text fields that arrive while a file is in flight are queued on the tail file's `queuedFields`; fields that arrive when the list is empty resolve immediately. `flush()` walks from the head, resolving each completed file followed by its queued fields, and stops at the first file that hasn't ended yet. The backing FormData now matches the payload's order, restoring the contiguity assumption (and fixing the long-standing reorder as a side effect). The same change is applied to all five copies in `react-server-dom-{webpack,turbopack,parcel,esm,unbundled}`. Two new tests cover the multi-file interleave.
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| if (typeof File === 'undefined') { | ||
| // Older Node.js versions do have support for Files in FormData but don't expose | ||
| // the constructor globally. | ||
| const formData = new FormData(); | ||
| formData.append('a', new Blob(['a'], {type: 'text/plain'}), 'a.txt'); | ||
| const arbitraryFile = formData.get('a'); | ||
| globalThis.File = arbitraryFile.constructor; | ||
| } |
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Also new to accomodate older Node.js versions. Only needed for assertions.
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May 29, 2026
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Backports #36468 to 19.1.x