catch error 400

[Nicole]

Here is a nice site, which gives me free news.
It is not nice any more, if I key in anything, which is not found.
Then there pops up 2 times "error 400".
This is rather annoying to click away and I would prefer it return a silent "nothing found" instead.
I am not familiar where I hop on an catch those replies and where exactly to hook in.
Can you give me a hint please?
The function reads (the last line is formatting it):

Code: Pascal  [Select][+][-]

1. // sucht zu einem Ticker die Nachrichten
2. function TNews.Suche_NewsZu(Ticker: string; abDatum, bisDatum: TDate): string;
3. var URL, Response: string;
4.     HttpClient: TFPHTTPClient;
5.     JsonResponse: TJSONData;
6.     ts_ab, ts_bis: Int64;
7.     s_from, s_to: string;
8. begin
9.   Result := '';
10.  
11.   ts_ab := DateTimeToUnix(abDatum);
12.   ts_bis := DateTimeToUnix(bisDatum + 1);  // period2 ist exklusiv!
13.  
14.   s_from := IntToStr(ts_ab);
15.   s_to := IntToStr(ts_bis);  // brauche ich offenbar nicht, kam von Yahoo-Vorlage
16.  
17.   URL := 'https://newsapi.org/v2/everything?q=' + Ticker +
18.   '&from=' + s_from + '&sortBy=publishedAt&apiKey='+ APIKEY_News;
19.  
20.   HttpClient := TFPHTTPClient.Create(nil);
21.   HttpClient.AddHeader('User-Agent', 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36');
22.   try
23.     Response := HttpClient.Get(URL);
24.     JsonResponse := GetJSON(Response);
25.     Ersetze.JsonWirdDatei(JsonResponse, 'myNews_json');  // ich speichere es einmal ab
26.     result:=JsonResponse.FormatJSON([]);
27.  
28.     result:=VerarbeiteArtikel(result); //VerarbeiteAntwort(result);
29.   finally
30.     HttpClient.Free;
31.   end;
32. end;        

[paweld]

Use try..except block.

Code: Pascal  [Select][+][-]

1. // sucht zu einem Ticker die Nachrichten
2. function TNews.Suche_NewsZu(Ticker: string; abDatum, bisDatum: TDate): string;
3. var URL, Response: string;
4.     HttpClient: TFPHTTPClient;
5.     JsonResponse: TJSONData;
6.     ts_ab, ts_bis: Int64;
7.     s_from, s_to: string;
8. begin
9.   Result := '';
10.  
11.   ts_ab := DateTimeToUnix(abDatum);
12.   ts_bis := DateTimeToUnix(bisDatum + 1);  // period2 ist exklusiv!
13.  
14.   s_from := IntToStr(ts_ab);
15.   s_to := IntToStr(ts_bis);  // brauche ich offenbar nicht, kam von Yahoo-Vorlage
16.  
17.   URL := 'https://newsapi.org/v2/everything?q=' + Ticker +
18.   '&from=' + s_from + '&sortBy=publishedAt&apiKey='+ APIKEY_News;
19.  
20.   HttpClient := TFPHTTPClient.Create(nil);
21.   HttpClient.AddHeader('User-Agent', 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36');
22.   try
23.     try
24.       Response := HttpClient.Get(URL);
25.     except
26.       on E: EHttpClient do
27.       begin
28.         case HttpClient.ResponseStatusCode of
29.           401: Caption := 'Unauthorised';
30.           404: Caption := 'Not found';
31.           else
32.             Caption := Format('error: %d', [HttpClient.ResponseStatusCode]);
33.         end;
34.       end;
35.     end;
36.     JsonResponse := GetJSON(Response);
37.     Ersetze.JsonWirdDatei(JsonResponse, 'myNews_json');  // ich speichere es einmal ab
38.     result:=JsonResponse.FormatJSON([]);
39.  
40.     result:=VerarbeiteArtikel(result); //VerarbeiteAntwort(result);
41.   finally
42.     HttpClient.Free;
43.   end;
44. end;  
45.  

[Nicole]

Thank you, looks good, but does not work yet.
I read
"u_news.pas(218,16) Error: Identifier not found "Caption""

at

Code: Pascal  [Select][+][-]

1.  case HttpClient.ResponseStatusCode of
2.           401: Caption := 'Unauthorised';  

If I change caption to result, the error message comes back

Code: Text  [Select][+][-]

1. [Window Title]
2. Fehler
3.  
4. [Content]
5. Projekt project_Tiger hat Exception-Klasse »External: ACCESS VIOLATION« ausgelöst mit der Meldung:
6. Access violation reading from address $0000000000000000.
7.  
8.  Bei Adresse 10011AEC3
9.  
10. [Ok]

followed by an access-thing because it is not json any more.

[paweld]

You only showed one function, so I thought TNews was a Form and I wanted to display message on its title.
If it is a class then instead of to Caption you can assign this message as a function result or to some property storing the last error etc.