如何识别 JavaScript 客户端上的 SignalR 核心集线器错误？

Question

我们正在尝试在 JavaScript 客户端的 SignalR Core 调用方法上设置错误处理，该客户端需要识别错误的类型并采取相应的操作（例如，如果是授权错误，则应提示用户登录等）。我们确定从集线器返回的错误包含一条消息和一个堆栈属性，并构建了以下内容，根据消息属性中包含的文本设置错误代码：错误文本是否总是以英文返回（因此可以用于识别错误）？或者有更好的方法来实现这一目标吗？我们正在使用 .Net Core 3.1 和 @microsoft/signalr 3.1.10。

Answer 1

根据GitHub上的aspnetcore/SignalR服务器端代码，看来调用错误确实是通过字符串值传递的。

负责发送错误的方法定义如下：

private async Task SendInvocationError(string invocationId, HubConnectionContext connection, string errorMessage)

{

    if (string.IsNullOrEmpty(invocationId))

    {

        return;

    }

    await connection.WriteAsync(CompletionMessage.WithError(invocationId, errorMessage));

}

以及一些关于如何调用它的示例：

if (!await IsHubMethodAuthorized(scope.ServiceProvider, connection, descriptor, hubMethodInvocationMessage.Arguments, hub))

{

    Log.HubMethodNotAuthorized(_logger, hubMethodInvocationMessage.Target);

    await SendInvocationError(hubMethodInvocationMessage.InvocationId, connection,

        $"Failed to invoke '{hubMethodInvocationMessage.Target}' because user is unauthorized");

    return;

}

var errorMessage = ErrorMessageHelper.BuildErrorMessage($"Failed to invoke '{bindingFailureMessage.Target}' due to an error on the server.",

    bindingFailureMessage.BindingFailure.SourceException, _enableDetailedErrors);

return SendInvocationError(bindingFailureMessage.InvocationId, connection, errorMessage);

有关错误的唯一信息是 的字符串参数errorMessage。

另一方面，客户端 javascript 库源代码：

HubConnection.prototype.connectionClosed = function (error) {

    this.logger.log(_ILogger__WEBPACK_IMPORTED_MODULE_2__["LogLevel"].Debug, "HubConnection.connectionClosed(" + error + ") called while in state " + this.connectionState + ".");

    // Triggering this.handshakeRejecter is insufficient because it could already be resolved without the continuation having run yet.

    this.stopDuringStartError = this.stopDuringStartError || error || new Error("The underlying connection was closed before the hub handshake could complete.");

    // If the handshake is in progress, start will be waiting for the handshake promise, so we complete it.

    // If it has already completed, this should just noop.

    if (this.handshakeResolver) {

        this.handshakeResolver();

    }

    this.cancelCallbacksWithError(error || new Error("Invocation canceled due to the underlying connection being closed."));

    

    ...

};

这表明这"Invocation canceled due to the underlying connection being closed."是服务器未提供任何信息时的默认错误消息。

因此，我相信如果SignalR团队没有改变错误消息发送机制，你的string.includes做法是合理的。