Handling the -F option of Curl

[WyoMurf]

Are you requesting support for a new curl flag? If so, what is the flag and the equivalent Go code?

# (curl –X POST https://ssomesite.com/convert \
-F “media[file_data]=@/tmp/Example.wav;type=audio/x-wav” \
-F “account_did=5555555555” \
-F “api_key=a28f48da8da33402daef356abc567abfedc” \
-F “media[external_id]=123456789” \
-F “media[sender_id]=444-555-6666” \
-F “media[sender_name]=Mark Smith” \
-F “media[receiver_id]=333-555-1212” \
-F “media[receiver_name]=James Jones” \
-F “media[external_id]=4aef5432” \
-F “media[external_data]=Free-form text relative to your use case.”

// (no idea

I am looking at trying to make a complex request (like the above), and with the curl request (see above), code it up using the Go's net/http package.

Now, my main concern is that I am relatively new to the net/http package. It looks and feels pretty powerful, so I suspect this could be done. Your little curl-to-go program, and the example code have fired the imagination. I think I might be able to supply a -F option to code, but I need a nudge in the right direction.

If you were to code up (in go) the conversion, how would you (from a high-level perspective) do it? A little point in the right direction can get me started pretty quickly.

The curl above results in this sequence: (trace from curl):
== Info: About to connect() to eps-4voice.nuancemobility.net port 443 (#0)
== Info: Trying 8.39.192.14... == Info: connected
== Info: Connected to eps-4voice.nuancemobility.net (8.39.192.14) port 443 (#0)
== Info: Initializing NSS with certpath: sql:/etc/pki/nssdb
== Info: warning: ignoring value of ssl.verifyhost
== Info: skipping SSL peer certificate verification
== Info: NSS: client certificate not found (nickname not specified)
== Info: SSL connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
== Info: Server certificate:
== Info: subject: CN=*.nuancemobility.net,OU=BOS,O=Nuance Communications Inc.,L=Burlington,ST=Massachusetts,C=US
== Info: start date: Jul 10 00:00:00 2020 GMT
== Info: expire date: Jul 11 12:00:00 2022 GMT
== Info: common name: *.nuancemobility.net
== Info: issuer: CN=DigiCert Global CA G2,O=DigiCert Inc,C=US
=> Send header, 344 bytes (0x158)
0000: POST /conversions/4voice-us-voicemail HTTP/1.1
0030: User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7
0070: NSS/3.44 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
00a0: Host: eps-4voice.nuancemobility.net
00c5: Accept: /
00d2: Content-Length: 202234
00ea: Expect: 100-continue
0100: Content-Type: multipart/form-data; boundary=--------------------
0140: --------744dab5b632c
0156:
<= Recv header, 23 bytes (0x17)
0000: HTTP/1.1 100 Continue
=> Send data, 187 bytes (0xbb)
0000: ------------------------------744dab5b632c
002c: Content-Disposition: form-data; name="media[file_data]"; filenam
006c: e="Example.wav"
009e: Content-Type: audio/x-wav
00b9:
=> Send data, 16383 bytes (0x3fff)
0000: RIFF$...WAVEfmt ........@....>......data.............. .........
0040: ............. .......(.........................................
0080: ................................................................
00c0: ................................................................
0100: ......0............. ............. .......0.....................
... (15 16k blocks of info snipped out...)
1080: ....D...............T...................t.............$.........
10c0: ............|$|.|,|&..............D.....D.<.............D...D.d.
1100: ..............<.......$.4...............
=> Send data, 1043 bytes (0x413)
0000:
0002: ------------------------------744dab5b632c
002e: Content-Disposition: form-data; name="account_did"
0062:
0064: 5555555555
0070: ------------------------------744dab5b632c
009c: Content-Disposition: form-data; name="api_key"
00cc:
00ce: a28f48da8da33402daef356abc567abfedc
00f8: ------------------------------744dab5b632c
0124: Content-Disposition: form-data; name="media[sender_id]"
015d:
015f: 444-555-6666
0164: ------------------------------744dab5b632c
0190: Content-Disposition: form-data; name="media[sender_name]"
01cb:
01cd: Mark Smith
01dc: ------------------------------744dab5b632c
0208: Content-Disposition: form-data; name="media[receiver_id]"
0243:
0245: 333-555-1212
025b: ------------------------------744dab5b632c
0287: Content-Disposition: form-data; name="media[receiver_name]"
02c4:
02c6: James Jones
02d9: ------------------------------744dab5b632c
0305: Content-Disposition: form-data; name="media[external_id]"
0340:
0342: 4aef5432
0362: ------------------------------744dab5b632c
038e: Content-Disposition: form-data; name="media[external_data]"
03cb:
03cd: Free-form text relative to your use case.
03e5: ------------------------------744dab5b632c--

Got any words of wisdom?

[mholt]

Here are the docs for curl -F: https://curl.haxx.se/docs/manpage.html#-F

This is not a simple one. :) However, it's ok to partially implement a flag as long as we make it clear what features or forms/syntaxes are supported.

What we need to do is make a POST request with multipart/form-data body in Go; here's a good starting point: https://www.google.com/search?q=golang+http+post+multipart%2Fform-data

You'll probably want to become familiar with how multipart uploads work, if you aren't already, and then there's a great package in the standard library that makes it pretty easy: https://golang.org/pkg/mime/multipart/

Here's a really simple example from the search results that shows the most basic use, I think: https://gist.github.com/andrewmilson/19185aab2347f6ad29f5

Hopefully that is helpful in giving you a good starting point!