topic Re: Passing parameters using PROC HTTP POST method in SAS Procedures

Passing parameters using PROC HTTP POST method

KAZ — Tue, 12 Dec 2017 16:39:20 GMT

I am attempting to retrieve a json response from an API. I am able to get a valid response using curl, but am unable to get PROC HTTP to work.

The curl statement requires a -d argument: -d '{"cpId": 1}'

I presume the IN= option in the PROC HTTP statement is the way to go but I receive a Bad Request error:

proc http webusername="&_user" webpassword="&_pwd"
    url="&_url"
    in='payload={"cpId": 1}'
    method="POST"
    out=_cpr
    headerout=_cprh;
    headers 'Content-Type' = 'application/json';
run;

I am running 9.4M4. Any suggestions?

Re: Passing parameters using PROC HTTP POST method

ChrisHemedinger — Tue, 12 Dec 2017 20:27:19 GMT

With the -d option, I think the server might be expecting the input to be URL encoded, right?

Can you try:

%let pl = %sysfunc(urlencode(payload={"cpId": 1}));
proc http webusername="&_user" webpassword="&_pwd"
    url="&_url"
    in="&pl."
    method="POST"
    out=_cpr
    headerout=_cprh;
    headers 'Content-Type' = 'application/json';
run;

Other stabs in the dark:

You didn't mention whether this was for a mutipart form, but in case it is, you might get something from this thread.
And this one about REDCap might also be similar.

Re: Passing parameters using PROC HTTP POST method

KAZ — Tue, 12 Dec 2017 21:11:34 GMT

I am still getting a 400 Bad Request error even after url encoding the IN string.

Re: Passing parameters using PROC HTTP POST method

ChrisHemedinger — Tue, 12 Dec 2017 21:17:21 GMT

I just noticed that your curl example does not have the keyword "payload". Is that correct?

If so, can you refine the attempt to:

%let pl = %sysfunc(urlencode({"cpId": 1}));
proc http webusername="&_user" webpassword="&_pwd"
    url="&_url"
    in="&pl."
    method="POST"
    out=_cpr
    headerout=_cprh;
    headers 'Content-Type' = 'application/json';
run;

If you can share what API you're trying to access (if it's publicly documented), we might be able to find the right approach.

Re: Passing parameters using PROC HTTP POST method

KAZ — Tue, 12 Dec 2017 21:32:13 GMT

I am attempting to hit the OpenSpecimen -> Get Registrations API. The documentation is here, but not very helpful.

The working curl code, with just the user and url removed is:

curl -H "Content-Type: application/json" -X POST -d '{"cpId": 1}'

Re: Passing parameters using PROC HTTP POST method

ChrisHemedinger — Tue, 12 Dec 2017 21:39:24 GMT

I can't get to that link -- hidden behind an Atlassian login. But have you tried once without the "payload=" and not a urlendoded version of the IN=?

Re: Passing parameters using PROC HTTP POST method

KAZ — Tue, 12 Dec 2017 21:48:02 GMT

Thank You! For posterity, here is the working code:

proc http webusername="&_user" webpassword="&_pwd"
    url="&_url"
    in='{"cpId": 1}'
    method="POST"
    out=_cpr
    headerout=_cprh;
    headers 'Content-Type' = 'application/json';
run;