Error Handling

Error Handling

A failed request throws an exception. Which one depends on what went wrong:

Exception	When
OjsValidationException	OJS rejected the values you sent: a 400 with per-field messages, or a 422 (invitations).
OjsApiException	Any other non-success status, such as 401, 403, 404 or 500.
HttpRequestException / TaskCanceledException	The network failed, or the request timed out.

OjsApiException has these properties:

Property	Content
StatusCode	The HTTP status code.
Error	The OJS error key, e.g. api.404.resourceNotFound.
ErrorMessage	The translated message.
ResponseBody	The raw body.
RequestMethod, RequestUri	Which request failed.

OjsValidationException inherits from it and adds Errors, a map from field name to messages. Multilingual fields are flattened, e.g. title.en.

Try
    Await ojs.Submissions.SubmitAsync(12, confirmCopyright:=True)
Catch ex As OjsValidationException
    For Each field In ex.Errors
        Console.WriteLine($"{field.Key}: {String.Join(" ", field.Value)}")
    Next
Catch ex As OjsApiException When ex.StatusCode = Net.HttpStatusCode.NotFound
    Console.WriteLine("No such submission.")
Catch ex As OjsApiException
    Console.WriteLine($"{CInt(ex.StatusCode)} {ex.Error}: {ex.ErrorMessage}")
End Try

try
{
    await ojs.Submissions.SubmitAsync(12, confirmCopyright: true);
}
catch (OjsValidationException ex)
{
    foreach (var field in ex.Errors)
        Console.WriteLine($"{field.Key}: {string.Join(" ", field.Value)}");
}
catch (OjsApiException ex) when (ex.StatusCode == System.Net.HttpStatusCode.NotFound)
{
    Console.WriteLine("No such submission.");
}
catch (OjsApiException ex)
{
    Console.WriteLine($"{(int)ex.StatusCode} {ex.Error}: {ex.ErrorMessage}");
}

try
    let! _ = ojs.Submissions.SubmitAsync(12, confirmCopyright = true)
    ()
with
| :? OjsValidationException as ex ->
    for field in ex.Errors do
        printfn "%s: %s" field.Key (String.Join(" ", field.Value))
| :? OjsApiException as ex when ex.StatusCode = Net.HttpStatusCode.NotFound ->
    printfn "No such submission."
| :? OjsApiException as ex ->
    printfn "%d %s: %s" (int ex.StatusCode) ex.Error ex.ErrorMessage

Status codes you will meet

Status	Typical Error	Meaning
401	user.authorization.roleBasedAccessDenied	The token is valid, but the user's role may not do this. OJS uses 401 here, not 403.
401	user.authorization.noContext, user.authorization.contextRequired	The endpoint needs a journal, but the client points at the site (_), or the journal path is wrong.
403	api.submissions.403.* and similar	The user may use the endpoint, but not on this object.
404	api.404.resourceNotFound	The object does not exist, or the user cannot see it.
400	doi.authorization.enabledRequired	DOIs are switched off in the journal.
400 / 422	field messages	Validation failed; you get an OjsValidationException.

Validate before you submit

SubmitAsync can run the checks without submitting:

Try
    Await ojs.Submissions.SubmitAsync(12, confirmCopyright:=True, validateOnly:=True)
    Console.WriteLine("Ready to submit.")
Catch ex As OjsValidationException
    Console.WriteLine(String.Join(Environment.NewLine, ex.Errors.Keys))
End Try

Cancellation and timeouts

Using cts As New Threading.CancellationTokenSource(TimeSpan.FromSeconds(10))
    Dim issue = Await ojs.Issues.GetCurrentAsync(cts.Token)
End Using

using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
var issue = await ojs.Issues.GetCurrentAsync(cts.Token);