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Overview

Both Generic OAuth2.0 and Callout Authenticator API policies contain a Response Handler field where you can specify how the response to the request is handled. The field has a default response that you can configure. You can use anything in the response received from the callout to your URL.

Default Expression

The Response Handler field does not display the default expression. When you configure the expression, you can copy and paste this expression in the empty field:

Default Response Handler Expression

match response

{
       { statusCode: 200..<300, entity } => Result.ok(entity),
       { statusCode: 401|404 } => Result.ignore(),
       { status } => Result.err(status),
       _ => Result.err('Invalid response: ' + response.toString())

}

Configuration

Inside of this Response Handler field are two expression objects available:

The "response" object, which contains the response from the callout to your URL.
The "Result" object, which contains functions to control how you want the response to be handled.

You can modify the default Response Handler expression according to your own response handling logic, using the functions inside the Result object defined in the following table:

Result Functions	Description
`{` `ok: entity => { variant: 'OK', value: entity }` `continue: entity => { variant: 'CONTINUE', value: entity }` `ignore: () => { variant: 'IGNORE' },` `err: reason => { variant: 'ERROR', reason: reason }}`	You call the `OK` function when you want the response to be accepted.
	You call the Continue function to perform multiple callouts on a single request in sequence using the response of the first call out in a subsequent callout for further validation.
	You call the `Ignore` function when you want the response to be ignored.
	You call the `Error` function when you want the response to result in an error.

The Continue function does not accept the request (differentiating it from the OK function); rather, it just saves the value in the target path for further callouts.

Troubleshooting

The response handler enables you to specify why a request failed. In certain scenarios when the client makes the HTTP call to the authorization/authentication server, you might see in the returned response that the error response handler returned the correct error in the “Failure” field of the response body, but that the server response is a 500 HTTP error.

This combination of errors is possible when the Policy executes correctly, but the response from the authentication endpoints results in an error that is not a 401/403 HTTP status code. If the authorization endpoint returns a 401/403 HTTP status code, then the Policy ignores the 401/403 HTTP status code and moves on to the next policy to try and authorize the request.

For example, an Org admin sets up the Callout Authenticator Policy to authenticate APIs based on a bearer token. In this policy, the following expression is configured for the Response Handler field:

Match response
{

  { statuCode: 200..<300, entity } => Result.continue(entity),

  { statusCode:400|401|404 } => Result.err(“bad request from testuser”),

  { status } => Result.err(status),

  _ => Result.err(‘Invalid response: ‘ + response.toString() )

}

However, when the Org admin tests an API, the response to the call displays a 500 HTTP error in the header of the test API call. The 500 HTTP error is the correct message that the client should see in the header of the returned response because the API call was never completed. The root cause might be due to a misconfigured policy downstream, a networking issue, or even mistyped user input.

SnapLogic Documentation

Response Handler Configuration

Overview

Default Expression

Configuration

Troubleshooting

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