openAPI client

[rnervi]

some1 can help with a simple, clear and easy snippet of code to deal with info supplied by  openAPI.com services ?
ty

[Thaddy]

Do you mean OpenAPI.it or OpenAI.com? A bit confusing. And then there is OpenApis.org...

[rnervi]

.com (and for me it opens the .it - same site with nationally interesting API)
it supplies some API services
and despite the .it or .com the interfacing way should be the same

[cdbc]

Hi
Cannot understand a word of it, api is in Italian?!?
Sorry, a waste of my time!
Regards Benny

[Zvoni]

acc. to https://swagger.io/specification/
it's JSON

[rnervi]

sure, it's json but didnt understood how to write dowb simple code to call and use answers. They supply some code snippet for many langs BUT object pascal.
meanwhile I asked them if any tutorial or code snippet natively.
then I change - simpyfing  - question:
is there a basic delphi code to call an api service and get answer (to be post processed) ?

[paweld]

Example of get data from endpoint IT-legalforms of company module. You need to generate a token in their panels or using the API.

Code: Pascal  [Select][+][-]

1. uses  fphttpclient, opensslsockets, fpjson;
2.  
3. const
4.   api_url = 'https://test.company.openapi.com/'; // for COMPANY module: <-- sandbox | production --> 'https://company.openapi.com/'
5.   YOUR_OpenAPI_Token = 'sample-OpenAPI-fake-token';  //paste your token
6.  
7. procedure TForm1.Button1Click(Sender: TObject);
8. var
9.   hc: TFPHttpClient;
10.   errmsg: String;
11.   jsonstream: TStringStream;
12.   jo: TJsonObject;
13. begin
14.   errmsg := '';
15.   hc := TFPHttpClient.Create(nil);
16.   hc.AllowRedirect := True;
17.   hc.RequestHeaders.Insert(0, 'Authorization: Bearer ' + YOUR_OpenAPI_Token);
18.   hc.RequestHeaders.Add('Content-Type: application/json');
19.   jsonstream := TStringStream.Create;
20.   hc.HTTPMethod('GET', api_url + 'IT-legalforms', jsonstream, [200, 202, 400, 401, 402, 403]); //sample endpoint
21.   if hc.ResponseStatusCode div 100 = 2 then //if response OK
22.     Memo1.Lines.Add(jsonstream.DataString)  //here I add response to TMemo, but you can process and get the information you need, just as I did below
23.   else
24.   begin
25.     if jsonstream.DataString <> '' then
26.     begin
27.       jo := TJsonObject(GetJson(jsonstream.DataString));
28.       if jo.Find('message') <> nil then
29.         errmsg := jo.Find('message').AsString;
30.       jo.Free;
31.     end;
32.     ShowMessage(Format('Error: [%d] %s' + #13#10 + 'OpenAPI Error Message: %s', [hc.ResponseStatusCode, hc.ResponseStatusText, errmsg]));
33.   end;
34.   jsonstream.Free;
35.   hc.Free;
36. end;                      

[rnervi]

oh ! many thanks
will analyze and test it
yes I know for the token from cpanel
ty

[rnervi]

for the correctness
must copy libeay32.dll and ssleay32.dll inside the dir for exe file, to avoid "cannot initialize ssl library"
and .. it works !
ty a lot (spent last 2 days in figure howto!)

[gidesa]

There is this library, for FPC and Delphi:

https://github.com/landgraf-dev/openai-delphi

[rnervi]

@paweld: worked like a charm ! now it's clear. ty again !

[Thaddy]

There is this library, for FPC and Delphi:

https://github.com/landgraf-dev/openai-delphi

That is quite, he uses my code I published one day after the API was officially released as beta. Christmas 2022.. Anyway, that is free to use without restrictions.
It originates from FreePascal for that reason.....(proof is on this forum)
There is a nice little anecdote: you need a developer key to use GPT and mine expired a couple of months later. Nice thing is I explained, showed what I did, proved my age (pensionado), and... got a new key... which does not seem to expire!. Thank you, OpenAI and Microsoft!!

[abouchez]

I was not please with the Wagner code, clearly not really FPC friendly, and was not able to find Thaddy's original code.

So I made my own OpenAPI client generator:
https://blog.synopse.info/?post/2024/09/06/Swagger/OpenAPI-Client-Generator-for-Delphi-and-FPC
 

Here are some features of our OpenAPI code generator for Delphi and FPC:
- Use high-level pascal records and dynamic arrays for "object" DTOs
- Use high-level pascal enumerations and sets for "enum" values
- Translate HTTP status error codes into high-level pascal Exceptions
- Recognize similar "properties" or "enum" to reuse the same pascal type
- Support of nested "$ref" for objects, parameters or types
- Support "allOf" attribute, with proper properties inheritance/overloading
- Support "oneOf" attribute, for strings or alternate record types
- Support of "in":"header" and "in":"cookie" parameter attributes
- Fallback to variant pascal type for "oneOf" or "anyOf" JSON values
- Generated source code units are very small and easy to use, read and debug
- Can generate very detailed comment documentation in the unit source code
- Tunable engine, with plenty of generation options (e.g. about verbosity)
- Leverage the mORMot RTTI and JSON kernel for its internal plumbing
- Compatible with FPC and oldest Delphi (7-2009)
- Tested with several Swagger 2 and OpenAPI 3 reference content
But still not fully compliant to all existing files: feedback is welcome!

The source code of the generator is a single unit:
https://github.com/synopse/mORMot2/blob/master/src/net/mormot.net.openapi.pas

And you will find several generated sample code units in the blog article, to make yourself your idea about the level of this little unit.

Feedback is welcome!