error-flow.md

Handling Errors with an Error Flow

The error flow is triggered when certain severe errors occur while processing the flow, or when the error action is invoked. It is typically used to produce custom error messages or headers, or set the HTTP status. Another example is augmenting the access log with custom log fields.

In your swagger.yaml, point the top-level property x-flat-error to a flow file:

…
x-flat-error:
  flow: error.xml       # ⬅ error flow
…

In this example, we use error.xml to format a custom error message:

<flow>
  <template>
    {
      "CustomError":  {
        "Message": {{ $error/message }},
        "Info": {{ $error/info }}
      }
    }
  </template>
  <set-response-headers>
    {
      "Status": {{ $error/status }},
      "Error-Code": {{ $error/code }}
    }
  </set-response-headers>
</flow>

This will ensure that all errors that trigger the error flow will produce a consistent status, error message and headers.

Triggers

Error triggers are

• schema violations,
• security violations (JWT),
• request errors,
• or the error action

See also

• Error Flow
• $error