Use case: Exception Handler in financial transactions
Context
Imagine that a company's finance department needs to confirm whether each transaction processed by the payment system was successfully completed.
To do this, they rely on the following tools: the bank's API (REST module), the database, and Skyone Studio.
Unexpected issues may arise in any operation, such as payment authorization failures or inconsistent information. However, the finance department must verify each transaction, ensuring that payments are processed correctly and that the team is notified in case of errors. This facilitates monitoring and optimizes operational management.
In this documentation, we will explain how to use the "Exception Handler" feature to handle scenarios where the integration flow needs to continue even if some items encounter errors. Additionally, we will cover how to properly notify errors that occur throughout the flow execution.
Business Rule
When the REST module returns status code 422, it means the information is inconsistent.
When the REST module returns status code 400, the execution is expected to be terminated.
Technical Dictionary
HTTP Status code 422: Unprocessable Entity
HTTP Status code 400: Bad Request
Scenario without Exception Handler
Even if the status code indicates an error, by default, the platform does not consider it as such in REST cases. As a result, the transaction is inserted into the completed payments database, creating an inconsistency with the actual information.
Scenario with Exception Handler
With the "Exception Handler" functionality, any HTTP error will be captured and handled. By creating two independent Exception Handlers, we can differentiate the treatment: in the case of a 422 error, the system simply skips to the next transaction in the list, while in the case of a 400 error, the flow is interrupted.
Configuring the Exception Handler in Practice
After contextualizing our case, it's time to set up our flow.
Notice in the image below that we have a flow consisting of:
Webhook Trigger: The starting point and entry for the list of transactions to be processed by our flow.
Loop For: A tool module that facilitates the processing of lists of information.
REST Module: Validates the bank transaction, which will come as an element of the Loop For.
PostgreSQL: Records the completed payments.
When clicking on "Exception Handlers", we should click on "Add Exception Handler". The following screen will be displayed:
Based on the business rules mentioned above, we will add two Exception Handlers:
Status code 422: Unprocessable Entity
In "Handler General Settings", fill in the necessary details:
Handler Name: Unprocessable Entity
Handler Availability: Flow
Next, we will create a rule. To do this, click on "Add Rule" and fill in the following fields:
Rule Name: Status code 422
Attempts: 0
Waiting Time: 0
Regex code:
"status": 422Rule notifications: Local and Email
Message: Transaction not processed
Send parameters in the message? Yes
Final action: Continue loop
We finish the configuration by clicking "Save".
Status code 400: Bad Request
In "Handler General Settings", fill in the necessary details:
Handler Name: Transaction Bad Request
Handler Availability: Flow
Next, we will create a rule. To do this, click on "Add Rule" and fill in the following fields:
Rule Name: Status code 400
Attempts: 1
Waiting Time: 1s
Regex Code:
"status": 400Rule Notifications: Local and Email
Message: An error occurred during the transaction process.
Send parameters in the message? Yes
Final Action: Stop
We finish the configuration by clicking "Save".
When selecting the "Email" option in the "Rule Notifications" section, ensure that your email is set as the "Channel" to receive notifications and that the "Flows" option is enabled in the "Element Notifications" settings. For more information, see the "Notifications" article.
Additionally, make sure to add the email in the "Alerts" tab in the flow configuration. Read more here.
Adding Exception Handler to the Component
After the Exception Handlers are created, it's time to activate them in the component. In this example, we will activate the Exception Handlers in the "Validate Financial Transaction" module. To do this, simply click "edit" on this component.
Next, on the left-hand side, you will see that the previously created rules appear in the "Exception Handlers" section.
For our use case, we will activate the newly created "Exception Handlers" and organize them in the following order:
Unprocessable Entity
Transaction Bad Request
Execution Result
After everything is set up, we run our flow. In "Logs", we can check the execution result.
Unprocessable Entity
Transaction Bad Request
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