Working with multipart form data from HTTP trigger

[stuartmccoll]

Hi,

I'm trying to create a Power Automate flow which takes a file from multipart form data received via an HTTP trigger and then creates this file within OneDrive or SharePoint.

I've found a few older tutorials online which have enabled me to get to the stage where I can access the multipart form data and convert the base64 encoded version of the file into binary. If I run my Power Automate flow with only these steps, then it runs successfully. However, as soon as I add an extra block to the flow to do anything, I get back an InvalidRequestContext error from the flow.

Here's the version of the flow which works:

Working version of Power Automate flow

The first Compose section has an expression of 'triggerMultipartBody(0)'. The second Compose section has an expression of '

base64ToBinary(triggerMultipartBody(0)['$content'])'.

 

At this point, I add a step to create a file in OneDrive using a dummy file name and the output of the second Compose section.

 

Screenshot of non-working Power Automate flow

The error I receive from this is:

{

"error": {

"code": "InvalidRequestContent",

"message": "The input body for trigger 'manual' of type 'Request' must be of type JSON, but was of type 'multipart/form-data; boundary=--------------------------190915140118851309356544'."

}

}

I receive this same error message even if I try to create a static file without accessing the output of the second Compose section.

I've got a dummy JSON schema in the HTTP request, but the flow generates the same errors with or without this. In terms of the request, I'm sending it from Postman with a 'form-data' body which contains a single PNG file, and haven't changed anything else in Postman other than pasting in the HTTP trigger URL and selecting 'POST' as the HTTP method.

Would anybody know what's happening here?

[robertpagano]

Hey there!

Just curious if you ever got this to work. I am running into a similar issue.

Thanks!

[eliz_talent]

Hi!

I had the same problem.

What is more - if I delete the creation of file step - flow run with success.

The solution for me was to call child flow (thru HTTP request) with step to create file.

The main reason for the error you get is that trigger "When a HTTP request is received" cannot receive any type but application/json. So in trigger leave JSON Schema empty.

The child flow:

[winternvrland]

I'm having the same issue. Can you export the flow? I'm not quit understanding where to put the child flow?

[eliz_talent]

The main flow which I trigger from the button is very simple:

The last step is to send a request to child flow.

In URI you should specify the URI from the trigger of the child flow.

The Body:

{
"content": "@{triggerMultipartBody(0)['$content']}"
}

[winternvrland]

Update: Eliz you're a genius! It worked , all the kudos to you!

[kmin]

Hi I can't get this to work. Can you please look over to help?

I am getting a mismatch type error for string and object. This is how my http call to child looks.

Child flow:

[kmin]

Can you look over the issue that i am still having with this?  I feel like i have tried to duplicate but still getting a type mismatch error from the child flow. 

[eliz_talent]

Hi @kmin !

It looks like you forgot to add curly brackets in the body when calling a child flow :

{

"content":"..."

}

[kmin]

Hi, I did forget the brackets but added it in but gets the same error message below. I am triggering this from postman using an .jpg file in the body. The JSON schema in the child i copied from this post. If i change the 'object' to 'string' there, i get over this error but fails in 1st in the child.

"The input body for trigger 'manual' of type 'Request' did not match its schema definition. Error details: 'Invalid type. Expected String but got Object.'. "

[SteepM]

I have the same issue! With empty JSON Schema, I am getting "

The input body for trigger 'manual' of type 'Request' must be of type JSON, but was of type 'multipart/form-data;", I am trying exactly as shown https://www.youtube.com/watch?v=wJj0E1C4z0c&ab_channel=Dave%27sTechTips

With .pdf file