根據(jù)GitHub上的aspnetcore/SignalR服務(wù)器端代碼，看來調(diào)用錯誤確實是通過字符串值傳遞的。
負責(zé)發(fā)送錯誤的方法定義如下：
private async Task SendInvocationError(string invocationId, HubConnectionContext connection, string errorMessage)
{
if (string.IsNullOrEmpty(invocationId))
{
return;
}
await connection.WriteAsync(CompletionMessage.WithError(invocationId, errorMessage));
}
以及一些關(guān)于如何調(diào)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);
有關(guān)錯誤的唯一信息是 的字符串參數(shù)errorMessage。
另一方面，客戶端 javascript 庫源代碼：
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."));
...
};
這表明這"Invocation canceled due to the underlying connection being closed."是服務(wù)器未提供任何信息時的默認錯誤消息。
因此，我相信如果SignalR團隊沒有改變錯誤消息發(fā)送機制，你的string.includes做法是合理的。
