Get data from and send data to an external REST se...

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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.

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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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Get data from and send data to an external REST service

Get data from and send data to an external REST service