In this blog post, you will fetch the latest currency exchange rates from a remote server using the Oracle APEX RESTFUL Data Source utility.
Restful Data Source Modules act as a reference to one or multiple external restful services. A module can contain one or many restful data Source Operations which are the references to a concrete external restful service.
Restful Data Source Modules enable developers to access Representational State Transfer (REST) services or generic JSON data feeds in applications and use the data in Application Express components such as interactive reports and interactive grids. Unlike existing restful Service References, a Restful Data Source Module contains metadata about the restful service which can be used by Application Express Components or PL/SQL processes to invoke the service and to process the responses.
Fetch Data from an External Restful Data Source
First, you will
learn how to integrate data from an external restful data source into your APEX application.
You will integrate the latest currency exchange rates and currency conversions
into your APEX application by using a free currency API from the amdoren.com site.
This currency API is available in JSON format and easily accessible
through a simple API request over a secure HTTPS connection. Here are the steps
to accomplish this task:
1. Go to https://www.amdoren.com/currency-api/.
2. Click the Free Sign up! button
3.
Enter your credentials including
your e-mail address on the Developer Sign-Up page and click the Sign-Up button. You'll get a message
"Your account has been created. Please
check your email for your account details."
4. Open your email client and write down the password received from hello@amdoren.com.
5. Access the website using https://www.amdoren.com/developer/ and log in to the Developer area by entering your email ID and the password you received in your email.
6. After successfully logging in to your account, you will see your API key. Write down this key as well.
7. In APEX, go to Shared Components \ Restful Data Source Modules (under Data Sources) and click the Create button.
8. On the Method screen, select the From scratch option to create the restful data source module from scratch and click Next.
9.
On the General screen, select Simple
HTTP for the restful data Source Type and
enter Currency Converter for the restful data Source Name. Enter https://www.amdoren.com/api/currency.php
for URL Endpoint, which is the base
URL for the currency API. Click Next.
10. Accepting the values on the
Remote Server screen, click Next.
The Base URL is the URL of the chosen Remote Server object. The HTTP Endpoint
URL of this restful data source module is made up of the Base URL and the service-specific
path suffix, which appears in the Service URL Path underneath. The HTTP Endpoint URL is built by
appending a service-specific URL Path to the Base URL specified in the Remote
Server object.
11. Select No for Authentication Required and click the Advanced
button on the Authentication page to add some parameters.
12. On the Parameters screen, enter values as shown in the following figure and click the Discover button. Paste the API Key value you got in step 6 in the Value box next to the api_key parameter. The Preview screen will come up displaying a value in the Amount column under the Data tab. The Data Profile tab contains columns and type definitions. Click the Create Rest Data Source button to complete this process.
13.
Create a static List of Values named CURRENCIES as shown in the following figure.
The values used in this LOV will be used in two Select Lists on the application
page created next.
14. Create a Blank page and name it Currency Converter.
15. Add a region named Parameters to this new page.
16. Add the following three items to the Parameters region.
|
Property |
Item Value |
Item Value |
Item Value |
|
Name |
P4_FROM |
P4_TO |
P4_AMOUNT |
|
Type |
Select
List |
Select
List |
Text
Field |
|
Label |
From
Currency |
To
Currency |
Amount |
|
List of Values Type |
Shared
Components |
Shared
Components |
- |
|
List of Values |
CURRENCIES |
CURRENCIES |
- |
17.
Add a Classic Report region to
the page with the following attributes:
|
Property |
Value |
|
Title |
Current
Rate |
|
Type |
Classic
Report |
|
Location |
Web
Source |
|
Module |
Currency
Converter |
18. Expand the Parameters sub-region under the Current
Rate Classic Report region. The region contains the three parameters you
defined while creating the Rest Data Source module. At this stage, the parameters
exist with the same values you defined in Step 12. In order to make the module
more flexible, you need to replace these static values with the values you select
through the three parameters created in step 16. Click the Amount parameter, set its Type
to Item, and Item to P4_AMOUNT to map
this parameter to the value of the P4_AMOUNT text field item. Similarly, change the
Type and Item attributes of From and To parameters to P4_FROM and P4_TO,
respectively.
19. Add a new button to the page
with the following attributes. After you select your desired currencies and
input a value, you hit this button to calculate the conversion amount.
|
Property |
Value |
|
Button Name |
CALCULATE |
|
Label |
Calculate |
|
Region |
Parameters |
|
Button Position |
Copy |
|
Action |
Submit
Page |
20. Save and run the page. Select
different currencies using the From and To select lists, enter some value in
the Amount text field and hit Calculate. The API specified in the Restful Data Source
module will perform real-time conversion and will display the exchange rate in the
Amount column, as shown in Figure 6.
For Visual Instruction Watch This Video
