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Get data from and send data to an external REST service
The following example combines all the different HTTP classes and functions to retrieve data from an external service. The external service returns a JSON document with user information. You can use the jsonplaceholder.typicode.com website to test REST services. Additionally, you can request, add, and edit data from that website because it is a free space for you to practice.
procedure GetUserInformation(UserNumber: Integer)
var
Client: HttpClient;
ResponseMessage: HttpResponseMessage;
ResponseString: Text;
begin
if not Client.Get(StrSubstNo('https://jsonplaceholder.typicode.com/users/%1',
UserNumber), ResponseMessage) then
Error('The call to the web service failed.');
if not ResponseMessage.IsSuccessStatusCode() then
Error('The web service returned an error message:\\' +
'Status code: ' + Format(ResponseMessage.HttpStatusCode()) +
'Description: ' + ResponseMessage.ReasonPhrase());
ResponseMessage.Content().ReadAs(ResponseString);
end;
The ResponseString variable will contain the JSON document as a string. You can use the built-in JSON classes to parse the string and work with the content. You can also use the HttpClient class to upload data to a REST service. The subsequent code example sends data and an image to an external service. This service can, for example, perform image processing. In this example, the first picture from a certain item is retrieved. The Picture field in Items is a MediaSet field; therefore, it can contain multiple images. Those images are stored in the Tenant Media table.
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