[SOLVED] Response Code for Post request (fphttpclient)
lazarus / 38-Networking and Web Programming

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yus · 2021-07-15 19:58

Hello! I try create POST request:
Code:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
project1; uses  Classes,  SysUtils,  fphttpclient, 
opensslsockets; var  http: TFPHTTPClient;  answer: string;  str:
string; begin  http := TFPHTTPClient.Create(nil);  str :=
'[624049117,2114097675]';       answer := http.SimpleFormPost('https:/
/esi.evetech.net/latest/characters/affiliation/?datasource=tranquility
', str);  writeln(answer);  WriteLn('Error Code: ',
http.ResponseStatusCode);  answer := http.Get('https://esi.evetech.net
/latest/characters/2114097675/?datasource=tranquility'); 
writeln(answer);  WriteLn('Error Code: ', http.ResponseStatusCode); 
readln;  FreeAndNil(http);end.
Why for POST request error code always = 0?
GET request is good.

Thanks.

PS:
Lazarus 2.1.0
FPC Version: 3.3.1
SVN Revision: 65168

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Gustavo 'Gus' Carreno · 2021-07-15 21:31

Hey Yus,

These are my investigations using httpie(command line http).

First we need to create the file with the input:
Code: Bash  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i $ echo
"[624049117,2114097675]" > input.txt
Then I tested with a GET to see what happens:
Code: Bash  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i $ http
--json --verbose "https://esi.evetech.net/latest/characters/affiliatio
n/?datasource=tranquility"GET
/latest/characters/affiliation/?datasource=tranquility HTTP/1.1Accept:
application/json, */*;q=0.5Accept-Encoding: gzip, deflateConnection:
keep-aliveContent-Type: application/jsonHost: esi.evetech.netUser-
Agent: HTTPie/2.2.0   HTTP/1.1 405 Method Not AllowedAccess-Control-
Allow-Credentials: trueAccess-Control-Allow-Headers: Content-
Type,Authorization,If-None-Match,X-User-AgentAccess-Control-Allow-
Methods: POST,OPTIONSAccess-Control-Allow-Origin: *Access-Control-
Expose-Headers: Content-Type,Warning,ETag,X-Pages,X-ESI-Error-Limit-
Remain,X-ESI-Error-Limit-ResetAccess-Control-Max-Age: 600Allow:
POST,OPTIONSConnection: keep-aliveContent-Language: en-usContent-
Length: 30Content-Type: application/json; charset=utf-8Date: Thu, 15
Jul 2021 21:01:40 GMTStrict-Transport-Security: max-age=31536000Vary:
Accept-LanguageX-Esi-Error-Limit-Remain: 99X-Esi-Error-Limit-Reset:
20 {    "error": "method not allowed"}
So as you can see the GET should give you a 405 Method Not Allowed and
not an OK like you reported.

Once you do a POST with the data you provided:
Code: Bash  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i $ http
--json --verbose "https://esi.evetech.net/latest/characters/affiliatio
n/?datasource=tranquility" < in.txt POST
/latest/characters/affiliation/?datasource=tranquility HTTP/1.1Accept:
application/json, */*;q=0.5Accept-Encoding: gzip, deflateConnection:
keep-aliveContent-Length: 23Content-Type: application/jsonHost:
esi.evetech.netUser-Agent: HTTPie/2.2.0 [    624049117,   
2114097675] HTTP/1.1 200 OKAccess-Control-Allow-Credentials:
trueAccess-Control-Allow-Headers: Content-Type,Authorization,If-None-
Match,X-User-AgentAccess-Control-Allow-Methods: POST,OPTIONSAccess-
Control-Allow-Origin: *Access-Control-Expose-Headers: Content-
Type,Warning,ETag,X-Pages,X-ESI-Error-Limit-Remain,X-ESI-Error-Limit-
ResetAccess-Control-Max-Age: 600Allow: OPTIONS,POSTConnection: keep-
aliveContent-Length: 156Content-Type: application/json;
charset=UTF-8Date: Thu, 15 Jul 2021 21:02:08 GMTStrict-Transport-
Security: max-age=31536000X-Esi-Error-Limit-Remain: 100X-Esi-Error-
Limit-Reset: 52X-Esi-Request-Id:
648f51fa-e265-4765-8c5e-fd04ff48154e [    {        "alliance_id":
1354830081,        "character_id": 2114097675,       
"corporation_id": 98502318    },    {        "alliance_id": 99003581, 
      "character_id": 624049117,        "corporation_id": 98285865   
}]
The result is code 200 OK and then data is returned.

QuoteSide Note:
It's imperative that you have good debugging tools at your disposal
when you're dealing with HTTP services.
You need to FIRST be sure of what the service needs in order to THEN
do a good job in code.
httpie is a good command line tool if you like the CLI life.
There's also Postman if you're more into the GUI life.
Delphi also comes with a GUI client for this purpose, but after ~3
simple Google searches I couldn't find a link to it, sorry

As a principal rule of thumb when you're making a call to a service
that deals in JSON you should AT LEAST include the following header:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
http.AddHeader('Accept: application/json');
And if you're POSTing any JSON, then you should, also as a rule of
thumb, include the following header:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
http.AddHeader('Content-Type: application/json')
Only then can you be sure that you've made sure to adhere to the most
basics of the specs in terms of any JSON webservice.

Add those headers to your code and then tell us if anything changed.

Cheers,
Gus

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yus · 2021-07-16 06:11

Change SimpleFormPost to FormPost.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  answer :=
http.FormPost('https://esi.evetech.net/latest/characters/affiliation/?
datasource=tranquility', str);

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Gustavo 'Gus' Carreno · 2021-07-16 17:56

Hey Yus,

Quote from: yus on July 16, 2021, 08:11:20 amChange SimpleFormPost to
FormPost.

And that was enough to get you a result?

Ok, that works too

Cheers,
Gus

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yus · 2021-07-19 18:43

Quote from: Gustavo 'Gus' Carreno on July 16, 2021, 07:56:18 pmAnd
that was enough to get you a result?

Yes.

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krolikbest · 2021-07-19 19:25

Hi
 there it is an explanation (by Leledumbo) why in that way and not the
other
 https://forum.lazarus.freepascal.org/index.php/topic,37563.msg252820.
html#msg252820

Regards,