Fetching same endpoint with different keys

[LuisBrime]

Hi! I'm currently working with NextJS and SWR. I created an Next API endpoint (/api/files/[fileId]) that fetches a File from an external API and I'm trying to integrate it on a view that downloads 2 different files at the same time.

My issue is that both fetches are returning the same output even though I'm using different keys for each one; the code looks something like this:

• /api/files/[fileId].ts

// ...
export default async (req: NextApiRequest, res: NextApiResponse) => {
    if (req.method === 'GET') {
        const { fileId } = req.query
        const downloadedFile = await api.file.get(fileId)
        res.status(200)
        downloadedFile.pipe(res)
    }
}

I defined a reusable hook:

• lib/api/hooks.ts

import axios from 'axios'
import useSWR from 'swr'

export const useFile = (fileId: string | null) => {
    const { data, error } = useSWR(
        fileId,
        async () => (
            await axios.get(`/api/files/${fileId}`, {
                responseType: 'blob',
            })
        ).data,
    )

    return { error, file: data, isLoading: !error && !data }
}

Using the hook on the page, each File ID comes from a different fetch done elsewhere:

• pages/user.tsx

import { useFile } from 'lib/api/hooks'
// ...
const Page: NextPage = () => {
    // ...

    const { file: firstFile, isLoading: firstLoading } = useFile(firstFileId)
    const { file: secondFile, isLoading: secondLoading } = useFile(secondFileId)

    // ...
}
// ...

If I comment out one of the useFile calls, the other fetches correctly and uses its corresponding data, i.e: Each fetch works fine individually. The issue comes when I'm trying to do both at the same time, because both have the same data.

I'm not sure if I'm missing something, but hopefully someone could clear my mind a bit.

If any more info is needed to solve my question, I'll gladly share anything. Thanks a lot!

[LuisBrime]

Solved.

This was an issue with the library used to fetch the file, nothing to do with Next nor SWR, my bad!