Would you like to enhance your application with Real-Time & Historical World Weather Data information? Wouldn’t it be nice to have a API to retrieve instant, accurate weather information for any location in the world in lightweight JSON format? More importantly, do you want to do all that with the smallest possible amount of code and yet keep it easy to understand and completely maintainable? Follow along for all this and more!
The Low Code way to write apps
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 RAD Studio LowCode Wizard in addition to a REST client library to take advantage of WeatherStack API and retrieve a JSON format response for Current Weather, Historical Weather, Time-Series and Forecast API Endpoints.
The WeatherStack API is easy to use with RAD Studio
WeatherStack API offers instant access to current weather data for millions of global locations, powered by rock-solid data sources and refreshed in real-time. This is possible to be done for free (up to first 250 calls/month; no credit card required) and much more is available at very affordable prices and scalable to the use you make with no upfront commitments. The data comes from some of the largest weather stations and weather data providers in the world, all of which are closely monitored for consistency and data accuracy around the clock.
Our RAD Studio and Delphi applications will be able to call the API and request information based on the name of the city you provide.
How do I set up the WeatherStack API?
Make sure you refer to WeatherStack API website (https://weatherstack.com/) and 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 WeatherStack API endpoints?
Now all we need to do is to call the API base URL (http://api.weatherstack.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 ednpoint we choose to call. One can do that using REST Client libraries available on several programming languages.
WeatherStack offers several API endpoints to choose from:
- Current Weather: Get current weather data.
- Historical Weather: Get historical weather data.
- Historical Time-Series: Get historical time-series weather data.
- Weather Forecast: Get weather forecast for up to 14 days.
- Location Lookup: Look up one or multiple locations.
Our demo will focus on the Current Weather 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 WeatherStack Quickstart guide (https://weatherstack.com/quickstart)
// Current Weather API Endpoint
? access_key = YOUR_ACCESS_KEY
& query = New York
// optional parameters:
& units = m
& language = en
& callback = MY_CALLBACK
What does the WeatherStack API endpoint return?
After the call the main results will be a very complete list with all sort of information you may need for your app to present the current weather to your user like temperature, wind, pressure, humidity, visibility and even the link for an icon representing the textual weather description.
"query":"New York, United States of America",
"country":"United States of America",
How do I connect my applications to the WeatherStack API?
Once you have followed basic steps to set up the WeatherStack 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.
Running the REST Debugger – an invaluable tool for working with APIs
Run your RAD Studio Delphi and on the main menu click on Tools > REST Debbuger. 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 shown below. In the image below as parameters I used the access key i copied from the WeatherStack API dashboard and query the current weather for my city Salvador-Bahia-Brasil.
How do I build an app which runs on Windows, macOS, Android and iOS and works with the WeatherStack 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 find the Low Code App Wizard directly via this link: https://getitnow.embarcadero.com/firemonkey-app-low-code-wizard/
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 customize it.
The app that Delphi builds for you is configurable through the wizard
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.
The final steps to making our weather app
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 WeatherStack API and we are able to receive JSON response for whatever city 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.weatherstack.com/current';
RESTClient1.HandleRedirects := True;
RESTClient1.RaiseExceptionOn500 := False;
//here is were we pass the access_key and city as parameters
RESTRequest1.Resource := Format('?access_key=%s&query=%s', [edit1.Text, edit2.Text]);
RESTRequest1.Client := RESTClient1;
RESTRequest1.Response := RESTResponse1;
RESTRequest1.SynchronizedEvents := False;
RESTResponse1.ContentType := 'application/json';
memo1.Lines.text := RESTResponse1.Content;
The sample application features a TEdit as a place to paste in the access key and another TEdit for the City 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 the image below as parameters I used the access key i copied from the WeatherStack API dashboard and query the current weather for my city Salvador-Bahia-Brasil and the result in our app is the same we got in REST Debugger.
In this blog post we’ve seen how to sign up for the WeatherStack API in order to get instant access to current weather 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 retrives the data ready for you to iterate!
Head over and download the full source code for this demo application from here: https://github.com/checkdigits/WeatherApp_WeatherStackAPI
RAD Studio Delphi allows you to easily and rapidly build applications which connect to powerful SDKs and APIs with very little or no code. Why not download a trial today?