REST errors
When trying to view a customer and their details or create a new customer in the app, the app can fail to retrieve or create the required data, and various errors are returned. In this example, we add error handling to the REST endpoint function to cater for the following errors:
- 401 Unauthorized
- 403 Forbidden
- Unexpected error
An error section is added to the REST endpoint functions for creating customers (POST), viewing customers (GET), and updating customers (PUT). In this section, the when property is configured with an expression that returns the response status from the endpoint, for example, =@ctx.response.status = 403. There are multiple when properties configured to catch a 401 and 403 error; all other response statuses are caught in the Unexpected error. Each when property has a title, icon, and description, which provides a user-friendly explanation of the error. Errors are written to the customers_error table, and the data written to the table is configured in the transform property. The table, in conjunction with the commandQueue is used to troubleshoot the error and create s that allows you to retry the REST call or delete the error from the commandQueue. See REST error handling for more information.
REST | Detail |
---|---|
URL | https://[your_rest_service]/api/customers |
Operation/Method | POST,GET,PUT |
In each of the REST function files (GET, POST, PUT), add an error section and configure the YAML to cater for a 401 and 403 error, and a section to cater for all other response errors.
Add a file under the datasource folder to configure the local data provider with the data returned from the customers_error table. This data is used to provide detail of the error in a and to configure actions allowing the item to be retried or deleted.
There are a number of options available to process items that are in an error state.
- Use the commandQueue. Items that return an error from the REST endpoint will remain on the commandQueue and are not automatically processed by the queue. You must configure an action to either retry the item or delete the item from the queue. The retry executes the REST call again.
- Use the customer_error table configured in the function. Use the data from the table in a to allow app users to resolve the error or delete the item in error.
Create two s to work with the items in the commandQueue. This is helpful for the solution owner or administrator to take action and delete errors in the queue or possibly retry the REST call to process the items in the queue that are in an error state. Configure a list containing all items in the commandQueue, add a left swipeable action to cater for the delete and retry actions, also add an onPress event to go to view the payload details of the item in error.
Create a list to list the records in the customers_error table. Provide detail of the error in the title and subtitle properties.
For performance and offline support the data is synced from the REST service as soon as the app is opened or receives focus. This is achieved by calling the global action in the onFocus events. The action.sync-entities action will delete any items from the local data provider that were deleted from the commandQueue.