CODEWITHSUNDEEP
azureasp.net-coreazure-functions
Dan Friedman
Dan Friedman

Reputation: 5218

Upload an image to Azure Functions using HttpRequest from Postman

I'm having a hard time getting an image uploaded to Azure Functions using HttpRequest. I'm specifically using HttpRequest because that's what the VS templates use. I've simplified the problem to a simple test case with Postman.

Function:

[FunctionName("Function1")]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post")]HttpRequest req)
{
    return new CreatedResult("", req.Form.Files[0].OpenReadStream());
}

Postman:

Method: POST
URL: [Function URL]
Headers:
    Content-Type: multipart/form-data
Body: binary with image selected

So what should happen is that I select a file to upload, I click "Send" to upload it to the Azure Function, which should automatically return the stream and display the picture in the Postman response.

But when I call it from Postman, an exception is thrown when it tries to read the stream:

"System.IO.InvalidDataException: Missing content-type boundary.\r\n at Microsoft.AspNetCore.Http.Features.FormFeature.GetBoundary(MediaTypeHeaderValue contentType, Int32 lengthLimit)\r\n at Microsoft.AspNetCore.Http.Features.FormFeature.InnerReadFormAsync(CancellationToken cancellationToken)\r\n at Microsoft.AspNetCore.Http.Features.FormFeature.ReadForm()\r\n at Microsoft.AspNetCore.Http.Internal.DefaultHttpRequest.get_Form()\r\n at [My code]"

Now if I were to switch this to use HttpRequestMessage like the old Azure Function templates and use req.Content.ReadAsStreamAsync(), it works like a charm.

But since the new templates use HttpRequest, this question is focused on the use of HttpRequest and its correct use. So how can I use HttpRequest to get this to work?

Upvotes: 1

Views: 2072

Answers (1)

Jerry Liu
Jerry Liu

Reputation: 17790

Postman provides a way to upload form-data, choose type as File and upload the image.(No need to set headers)

enter image description here

See this request header in Fiddler, Postman sets boundary automatically.

content-type: multipart/form-data; boundary=--------------------------970956809380964389175281

If we upload binary with content type header, the header is Content-Type: multipart/form-data, so that we got error of missing boundary.

Upvotes: 2

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