Missing Content-Type for BusBoy using Azure Function v4

[crizzs]

Hello Azure,

I am faced with this issue (missing Content-Type) while using the latest version of busboy on Azure Function v4 to process form data.

Noticed azure function field name is content-type instead of Content-Type. I have no such issue on azure function v3

[ejizba]

Hi @crizzs can you please provide more detailed sample code? In general request headers are supposed to be case-insensitive and I think busboy will handle both casings, so I suspect something else might be causing the problem

[crizzs]

Hello ejizba,

This issue is well-publicised under another repository, @anzp/azure-function-multipart (Used them for azure functions v3). BusBoy has an if-statement that is case sensitive. This is designed due to an underlying assumption that all headers automatically lowercases all incoming headers to make them easily accessible.
https://github.com/mscdex/busboy/blob/master/lib/index.js#L52

Issue flagged out by community as well:
anzharip/azure-function-multipart#637

Anyways I found a workaround to get through it by turning the headers back to an object for reprocessing. This will prevent busboy from flagging out the missing Content-Type.

Object.fromEntries(req.headers)

[ejizba]

Right so I don't think the problem is the casing of content-type, but just the fact that our request.query property is now of type URLSearchParams which doesn't have the headers directly on the object. In other words, request.query['content-type'] doesn't work but request.query.get('content-type') does.

Since busboy expects the headers to be directly on the object, I feel like your workaround Object.fromEntries(req.headers) is the correct/best way to do this.

Btw, if you haven't already, you could try doing request.formData() directly. It's less configurable than busboy, but for simple forms it'll get the job done.

[microsoft-github-policy-service]

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