anthropic.BetaFileUploadParams doesn't provide a way to set content-types

[WeiyuanSong]

When I tried to upload a PDF file using
resp, err := c.client.Beta.Files.Upload(ctx, anthropic.BetaFileUploadParams{ File: file, Betas: []string{"files-api-2025-04-14"}, }, option.WithHeader("Content-Type","application/pdf"))
It returns {"type":"error","error":{"type":"invalid_request_error","message":"file: Field required"}.
But when I don't specify the content-type, the content-type will default to application/octet-stream, which cannot be specified in Message API because it will complain it doesn't support application/octet-stream.

[Mathiasme]

Please share more about your file variable definition as I understand it should be of type anthropic.file.

I use this func : https://pkg.go.dev/github.com/anthropics/anthropic-sdk-go@v1.12.0#File

[WeiyuanSong]

My file variable is like this
file, err := os.Open(filePath) if err != nil { return "", fmt.Errorf("failed to open file: %w", err) } defer file.Close()
where filePath is "my_pdf_file.pdf".
The File field is just anything that implements io.Reader, right?

[WeiyuanSong]

Using anthropic.file worked. Docs on this should be more clear tho.