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Graph/pre-signed-upload-client-server-semantic-mismatch

AntiPattern

Multipart/Pre-signed Upload Semantics

pre-signed-upload-client-server-semantic-mismatch

Pre-signed URL uploads fail to behave as expected because client and server treat metadata, form parsing, and progress callbacks differently—so file parts can’t be inspected or parsed, metadata headers aren’t applied, and completion signals arrive without usable state.

Node Details

Public graph metadata

Updated6/28/2026

Connections

30 linked nodes

MATCHESSolution

the issue was that I was passing in the Data URI as well with the encoding of the file. Outcome: make sure that the string of the file that you're sending doesn't contain this value: `data:@file/png;base64,`.

MATCHESSolution

Use upload(`content/temp/${file.name}`, file, { handleUploadUrl, clientPayload }) and return the pathname settings from onBeforeGenerateToken()

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Create a POST request to generate a signedUrl on the server — Send that URL to the client and POST the upload form with image to the S3 bucket. Tension: bypassing the server. Outcome: With that url you can POST directly to S3.

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Store uploads in the serverless writable temp directory (os.tmpdir()) during the request and then persist the files externally (e.g., upload to object storage like S3) or stream them directly; update the Multer storage destination to use os.tmpdir() and avoid serving from a project-local uploads folder.

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In Postman, select form-data and type as File and upload the audio file. — POST /transcribe?song_name=wait&singer=hadar HTTP/1.1. Tension: Check the request body to make sure that it is in the correct format and none of the required fields are missed. Outcome: upload the audio file.

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Use a `preParsing` hook to adjust parsing behavior (e.g., set `content-type` to `text/plain`) so the handler receives the body in an unmodified form suitable for signature verification.

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Use a clean percent-encoded presigned URL and allow access via pre-signed URLs in the S3 bucket policy

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Those values require encoding per RFC 2047 — Using `x-amz-meta-filename` suggests that the user-provided meta-data is transferred via HTTP request headers. Tension: This does not work with AWS. Outcome: One Idea was to use the Base64 encoding and do the wrapping/quoting/envelope with string concatenation.

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adding a class that extends `OutputStream` and creates a multi-part upload when the buffer reaches the set limit — AWS minimum is 5MB. Tension: end size of the zip can be tens of GB. Outcome: I set it to 10MB.

MATCHESSolution

Adding `x-amz-meta-author` to the headers for the PUT request allowed the data to be available in the `HeadObjectCommand` — fetch(signedURL, { method: 'PUT', headers: {. Tension: `x-amz-meta-author` is nowhere to be found. Outcome: Metadata: { author: 'John Doe' }.

MATCHESSolution

I needed to use the MultipartCopy class found in the S3 SDK. Tension: Over 4.5 GB - Use MultipartCopy. Outcome: This is now working...

MATCHESSolution

when calling fetch — you created a pre-signed URL that includes a Content-Type header. Tension: you didn't indicate that header later when you used the URL.

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var md5Based64 = Convert.ToBase64Str — Upload using RestSharp: (failed - Bad Digest). Tension: BadDigest - The Content-MD5 you specified did not match what we received. Outcome: both have the same inputs.

MATCHESSolution

Include the Tagging value when creating the PutObjectCommand and ensure the presigner signs the x-amz-tagging header by passing `unhoistableHeaders: new Set(['x-amz-tagging'])`. Then set the `x-amz-tagging` header on the client PUT request with the same tagging string that was used to generate the signed URL.

MATCHESSolution

I needed to do the following instead: — s3.createPresignedPost(params, (err, data) => {. Tension: which DID return the key back in the fields. Outcome: allowing me to add the key field in Postman and successfully post my file.

MATCHESSolution

Use the `.presignURL` extension on the `GetObjectInput` and `PutObjectInput` structs — for downloading & uploading S3 objects. Tension: generate pre-signed URLs for downloading & uploading S3 objects. Outcome: Here is a fully working example I wrote:.

MATCHESSolution

For multipart + pre-signed uploads from expo react-native with express backend is as follows: — upload a large video file the fastest on RN Expo.

MATCHESSolution

Just changing the order of the form data in the frontend code worked for me. — uploading the file from Browser. Tension: Aws error message was misleading. Outcome: I just interchanged the position of `x-amz-signature` and `x-amz-security-token`.

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Use a collection with upload: true, submit a FormData POST to /api/media with file, then update the document with the returned file id

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after submitting. Tension: This is likely not what you intended. Outcome: startTransition(() => { formAction(newFormData); });.

MATCHESSolution

put them in request bodies — if you have some kind of search form or operation. Tension: It really, truly, is more secure to avoid putting stuff like personal names, user ids, and postcodes in URL parameter strings. Outcome: use POST.

MATCHESSolution

Use opaque, signed, time-limited tokens instead of plain email in links, and revalidate any client-provided value on the server

MATCHESSolution

If you want to have e.g. functionality such as signed (and/or encrypted) email then you'd use a higher level protocol such as PKCS#7 — If you want to have e.g. functionality such as signed (and/or encrypted) email. Tension: CMS supports both encryption (enveloped data) and signatures. Outcome: you can simply base64 encode it.

MATCHESSolution

Submit the form as POST while overriding the method using the `_method: 'patch'` field, and ensure `forceFormData: true` is set so the file is sent as multipart data.

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select the multipart data radio button — Postman typically handles the specifics of the multipart request. Tension: Did you manually specify a Content-Type header of multipart/form-data? Outcome: Postman would be more complex like this, for example:.

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And multipart file locationCreateFile = fileUpload. Tension: the API consistently picks up the old file instead of the modified version. Outcome: Then status 200.

MATCHESSolution

Form data should be read using `@RequestParam`, not with `@RequestBody` — if you really need JSON. Tension: you’ll have to split it into two separate calls. Outcome: one for the file (form-data) and another for the JSON payload.

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Failed to encode MIC. Tension: I want to sign the MDN based on the AS2 request. Outcome: Data must be specified.

MATCHESSolution

you need to hash the prepared PDF (with signature dictionary containing the placeholder) — If you want any decent PDF signature validator to positively validate your signature. Tension: not something else. Outcome: validators expect that the signed byte ranges encompass exactly everything except the placeholder itself.

MATCHESSolution

Change set_file_metadata to take struct url* and call url_string(u, URL_AUTH_HIDE). Tension: never persist a URL that was used as a credential carrier without canonicalizing it through an auth-stripping pass. Outcome: This is what upstream did in wget 1.20.1.

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