Errors

Exception and Throwable exceptions thrown during processing such as SQL driver errors, operation errors etc. will be converted into OData errors (opens new window).

OData errors have a suitable HTTP response code and a standard JSON object format to present information about the error.

An example OData error object:

{
  "error": {
    "code": "no_handler",
    "message": "No route handler was able to process this request",
    "target": null,
    "details": [],
    "innererror": {}
  }
}

Streaming responses

Lodata implements Streaming JSON by default. This is very efficient, but it can encounter a situation where a fatal error occurs part way through sending a response, and after sending a successful HTTP code to the client.

When this happens Lodata will leave the response as incomplete JSON, but will append the header OData-Error as a trailing header (opens new window) if supported by the transport protocol (eg HTTP/1.1 with chunked transfer encoding, or HTTP/2).

Calling clients can disable the streaming behaviour by setting the Accept header with a parameter that includes streaming=false.

For example: Accept: application/json;streaming=false. This will buffer the response server-side, and return only error information and correct status codes.

Alternatively, you can globally disable the streaming behaviour by setting streaming to false in the lodata.php config file. Clients that want the streaming behaviour in this case can still set the Accept header with a parameter of streaming=true.

Any calling client in streaming mode must be aware of this in order to deal with JSON responses that cannot be decoded, and in this event should check the trailing header to get the JSON error object.

Exceptions

To retrieve the original exception that caused the Lodata error, the getOriginalException() method can be used.

try {
  // XXX
} catch (ProtocolException $protocolException) {
  /** @var Throwable $originalException */
  $originalException = $protocolException->getOriginalException();
}

Or, if you have captured a Response object the exception can be obtained with:

$originalException = $response->exception->getOriginalException();