Wouldn’t it be nice to have real-time and historical currency information for your business and be able to instantly retrieve up-to-date exchange rate data for more than 168 world currencies? The currencylayer API is capable of delivering accurate exchange rates with data updates ranging from every 60 minutes down to stunning 60 seconds.
In this article we will see how fast and easy it is to use RAD Studio and Delphi to create a Firemonkey multidevice application using the LowCode Wizard in addition to a REST client library to take advantage of currencylayer API API and retrieve a JSON format response for currency exchange rates in real-time.
Our RAD Studio and Delphi applications will be able to call the API and request information based on the name of parameters you provide.
How do I set up the Currencylayer API?
Make sure you refer to Currencylayer API website (https://Currencylayer.com/) and sign up for the free Plan providing only your email and some basic information (no credit card required). Once you are in the website will redirect you to a Quickstart guide dashboard and your API Access Key will be provided. The Access Key unique, personal and is required to authenticate with the API. Keep it safe!
How do I call Currencylayer API endpoints?
Now all we need to do is to call the API base URL (http://api.currencylayer.com/) via a HTTP POST method with no JSON request body needed and some few requested parameters added to the URL address depending on the endpoint we choose to call. One can do that using REST Client libraries available on several programming languages.
Currencylayer offers five API endpoints to choose from
- live endpoint: request the most recent exchange rate data
- historical endpoint: request historical rates for a specific day
- convert endpoint: convert any amount from one currency to another using real-time exchange rates
- timeframe endpoint: request exchange rates for a specific period of time
- change endpoint: request any currency’s change parameters (margin and percentage), optionally between two specified dates
Our demo will focus on the Live Endpoint but all the others follow similar logic but with different parameters passed. For a complete and detailed list of endpoints and its parameters make sure you refer to Currencylayer Quickstart guide (https://currencylayer.com/quickstart)
? access_key = YOUR_ACCESS_KEY
& source = GBP
& currencies = USD,AUD,CAD,PLN,MXN
& format = 1
// more parameters available please refer to the API Documentation (<a href="https://currencylayer.com/documentation">https://currencylayer.com/documentation</a>)
What does the Currencylayer API endpoint return?
After the call the main results will be as shown below. The currencylayer API’s live endpoint is used to get the latest rates for all available or a specific set of currencies.
How do I connect my Delphi applications to Currencylayer API?
Once you have followed basic steps to set up the Currencylayer API we need to make sure we are able to connect and communicate with it before we start writing some code.
RAD Studio Delphi and C++Builder make it very easy to connect to APIs as you can you REST Debugger to automatically create the REST components and paste them into your app.
In Delphi all the job is done using 3 components tot make the API call. They are the TRESTClient, TRESTRequest, and TRESTResponse. Once you connect the REST Debugger successfully, copy and past the components you will notice that the API URL is set on the BaseURL of TRESTClient. On the TRESTRequest component you will see that the request type is set to rmPOST, the ContentType is set to ctAPPLICATION_JSON, and that it contains one request body for the POST.
How do I use the RAD Studio REST debugger to easily create and send REST requests to the API?
Run your RAD Studio Delphi and on the main menu click on Tools > REST Debugger. Configure the REST Debugger as follows marking the content-type as application/json, and adding the POST url, the JSON request body and the API key you created. Once you click the Send Request button you should see the JSON response, just like we demonstrated below.
How do I build a FireMonkey Multidevice (Windows/MacOS desktop or Android/iOS mobile) application using the Currencylayer API?
Low code app development is increasingly popular today, and for good reason: it speaks to the demand for software paired with the difficulty of creating it. In many ways, Delphi led the low code revolution: RAD, where you build software by connecting components in a visual designer, is low code. The key with many low code solutions is extensibility: low code which cannot be extended to a traditionally coded app has a hard upper limit of functionality. If you’re a technology adviser, you do not want to recommend something which will limit your client or company. The best development solutions that target low code provide an avenue to grow and extend. In this too, Delphi excels.
Until recently in Delphi you still had to create a new project and create the forms or screens yourself – no matter how little code you may have to write to get powerful functionality when you did. This is something we’ve now addressed with an addon to 10.4.2. Run your RAD Studio Delphi and on the main menu click on Tools > GetIt Package Manager. In GetIt for 10.4.2 and later search for “Low Code App Wizard for FireMonkey”, our technology for cross-platform applications. You can also look at the GetItNow web page here.
What type of low code app template should I use?
Now that you have installed Low Code App Wizard for FireMonkey and that you were able to sucessfully configure and test your API calls on the REST Debbuger, go back to the REST Debbuger and click the Copy Components button. Open RAD Studio Delphi and on the main menu click File > New> Multi-Device Application Delphi, select the Firemonkey Template App as shown below and follow some simples Wizard steps to create your Low Code application.
The result will be a fully functional cross-platform application, which already contains basic functionality that every mobile app will need — you can run and use the app as is — and hooks to build more, plus demonstrates application development best practices with a very clean extensible design to add more screens with low code, plus a set of tests to ensure your app remains high quality as you customise it.
What sort of screens can I automatically create with the RAD Studio FireMonkey Low Code App Wizard?
The app that Delphi builds for you is configurable through the wizard and you can choose any set of the following:
- User accounts: sign up, sign in, and a profile screen, with hooks for your own authentication
- Settings screen (where you can change the app theme (light or dark), plus some example settings you can reuse or extend)
- Contacts screen
- A database layer: using Interbase, store data in your app
- An example new screen you can use as a template or example for adding new functionality
As you can see the Wizard saves you a lot of time as it creates a complete project with many forms ready for you to implement the code. Open the recently created NewFormFrame and hit Ctrl+V in order to paste the components you copied from REST Debbuger. This acction will result in three components added to the the form RESTClient1, RESTRequest1 and RESTResponse1.
Now we will simply add very simple code to a TButton OnClick event to make sure every thing is configured correctly and voila! In five minutes we have made our very first call to Currencylayer API and we are able to receive JSON response for whatever parameter we want.
procedure TNewFormFrame.Button1Click(Sender: TObject);
memo1.Lines.text := '';
RESTClient1.Accept := 'application/json, text/plain; q=0.9, text/html;q=0.8,';
RESTClient1.AcceptCharset := 'UTF-8, *;q=0.8';
RESTClient1.BaseURL := 'http://api.currencylayer.com/live';
RESTClient1.HandleRedirects := True;
RESTClient1.RaiseExceptionOn500 := False;
//here is were we pass the access_key and additional parameters
RESTRequest1.Resource := Format('?access_key=%s¤cies=%s', [edit1.Text, edit2.Text]);
RESTRequest1.Client := RESTClient1;
RESTRequest1.Response := RESTResponse1;
RESTRequest1.SynchronizedEvents := False;
RESTResponse1.ContentType := 'application/json';
memo1.Lines.text := RESTResponse1.Content;
What does the example app look like when it is running?
The sample application features a TEdit as a place to paste in the access key and additional TEdit for each parameter, a TMemo to display the JSON results of the REST API call. Now you have every thing you need in order to interate with the response data and make your application process the information and present it visually in the way it better suits your needs!
In this blog post we’ve seen how to sign up for the Currencylayer API in order to get instant access to currency exchange rates data. We’ve seen how to use the RAD Studio REST Debugger to connect to the endpoint and copy that code into a real application. And finally we’ve seen how easy and fast it is to use RAD Studio Delphi and the Low Code App Wizard for FireMonkey to create a real Multidevice (Windows/MacOS desktop or Android/iOS mobile) application which connects to the API and retrieves the data ready for you to iterate!
Are there any more examples of the RAD Studio Low Code Wizard?
You can read more blog articles about the powerful and superbly time-saving Low Code Wizard by clicking here: https://blogs.embarcadero.com/?s=low+code
Where can I download the example app’s source code?
You can download the full example source code from here: https://github.com/checkdigits/CurrencyRatesApp_example
Turn your ideas into applications users will love – download a free trial of RAD Studio Delphi today.