Add non-binary file list option to make_form?

[ampu3ro]

This is more of a question than a request, as I may just be missing something...

I think it might be useful to be able to define the content-type for a non-binary element of a multipart form. Basically, I have this issue with binary & non-binary parts and I have a hunch that defining an intermediate case in make_form could do the trick:

curl_formadd(&post, &last, CURLFORM_COPYNAME, name, CURLFORM_COPYCONTENTS, body, CURLFORM_CONTENTTYPE, content_type, CURLFORM_END);

The idea is that I could pass a string with a defined content-type (similar to the second example here):

url <- "https://my_salesforce_instance/services/data/v39.0/sobjects/Document/"
header <-  httr::add_headers("my_salesforce_auth")

x <- data.frame(FolderId="a0a1300000ZG7u3",Name="test1.png")
json <- jsonlite::toJSON(unbox(x),pretty=T)
doc <- list(body=json,content_type="application/json")

tmp <- tempfile(fileext=".png")
png(tmp)
plot(mtcars)
dev.off()
body <- httr::upload_file(tmp)

httr::POST(url,header,body=list(entity_document=doc,Body=body),encode="multipart",verbose())

I couldn't get a local build of curl with this tweak to work, but I'm not at all confident writing C code. On the other hand this may not even be relevant to solve the issue. Any suggestions?

[jeroen]

Did you read the section on posting forms from the vignette? The curl::form_file function allows you to specify a content type. Perhaps you can use this?

[jeroen]

Hmm reading the SO, maybe I don't fully understand the question. Let me look into it better.

[ampu3ro]

Thanks for the quick reply. Yeah, I think what I'm describing is something between a simple character like foo, which is handled with

curl_formadd(&post, &last, CURLFORM_COPYNAME, name, CURLFORM_COPYCONTENTS, translateCharUTF8(asChar(val)), CURLFORM_END);

and a form file like logo which is handled with

curl_formadd(&post, &last, CURLFORM_COPYNAME, name, CURLFORM_FILE, path, CURLFORM_CONTENTTYPE, content_type, CURLFORM_END);

As mentioned above, I'm not even sure this will solve the problem so if you have any other ideas I'm open to them! Thanks

[jeroen]

I don't think there is a distinction between binary and non-binary data inside a multipart body. I think --data-binary simply means that you want to use multipart encoding.

Only multipart encoding supports setting a content type, from your example:

>> Content-Disposition: form-data; name="y"; filename="db_biggest_tables.csv"
>> Content-Type: application/octet-stream

If you post a x-www-form-urlencoded body, values simply get turned into a val=foo&val2=bar string so there is no way to specify a content type. Everything is just a string.

So I'm not sure what exactly it is that you want, but from your SO post it kind of looks like a bug on in the salesforge API?

[ampu3ro]

I guess, more to the point, I'm wondering if the multipart body could have a part with the header

>> Content-Disposition: form-data; name="entity_document"
>> Content-Type: application/json

This doesn't seem possible with curl because I can only get

>> Content-Disposition: form-data; name="entity_document"; filename="file1510059b5200f"
>> Content-Type: application/json

if I use form_file (technically httr::upload_file) or

>> Content-Disposition: form-data; name="entity_document"

if I POST the json/character directly.

It's certainly possible that Salesforce API has a bug, it just seems unlikely to me given how many organizations use it and how this operation is documented.

[jeroen]

OK I get it now. You want to set a Content-Type but not a filename for a given field?

[ampu3ro]

Yep! Sorry that wasn't very clear before. Do you think that might solve the issue? It's the only obvious mismatch I can see between Salesforce's example and mine. I can also imagine that functionality would be useful more generally, but I don't know enough about Curl to have a good sense.

[jeroen]

OK I have added a new function form_data which allows you to post a string or raw vector with a custom content type. Can you give this a try? To install the dev version of curl in a clean R session:

install.packages("https://github.com/jeroenooms/curl/archive/master.tar.gz", repos = NULL)

And then look at ?form_data

[ampu3ro]

Beautiful! Worked like a charm. I really appreciate the help and speed in execution

[ampu3ro]

Just closing the loop, httr::body_config will need updating in order work with this enhancement. Happy to post an issue on that repo tomorrow. Thanks again!