qxtwebjsonrpcservice: add a throwRPCError function to allow bailing in a slot

src/web/qxtwebjsonrpcservice.cpp

@@ -104,6 +104,7 @@ void QxtWebJsonRPCService::Private::readFinished()
 void QxtWebJsonRPCService::Private::handle(QxtWebContent *c)
 {
     QxtWebRequestEvent *event = content.take(c);
+    currentRequest = 0;
     c->ignoreRemainingContent();
 
     QString data = QString::fromUtf8(c->readAll());
@@ -143,6 +144,9 @@ void QxtWebJsonRPCService::Private::handle(QxtWebContent *c)
     }
 
     QVariant returnValue;
+    currentRequest = event;
+    currentRequestId = rid;
+    requestCanceled = false;
 
     Method method = methods.value(action.toUtf8() + QByteArray::number(args.count()));
     bool ok = false;
@@ -364,6 +368,9 @@ void QxtWebJsonRPCService::Private::handle(QxtWebContent *c)
         p->postEvent(err);
         return;
     }
+    if (requestCanceled) {
+        return;
+    }
 
     QVariantMap res;
     res.insert("result", returnValue);
@@ -390,6 +397,29 @@ QxtWebJsonRPCService::~QxtWebJsonRPCService()
     delete d;
 }
 
+/*!
+ * respond to the current request with an error.
+ *
+ * The return value of the current slot is NOT used.
+ * Instead null is returned, adhering to the jsonrpc specificaiton.
+ *
+ * Calling this function from somewhere else then a handler slot is undefined behaviour.
+ */
+
+void QxtWebJsonRPCService::throwRPCError(QVariant error)
+{
+    d->requestCanceled= true;
+    QxtWebRequestEvent *event = d->currentRequest;
+
+    QVariantMap res;
+    res.insert("result", QVariant());
+    res.insert("error", error);
+    res.insert("id", d->currentRequestId);
+    QxtWebPageEvent *err = new QxtWebPageEvent(event->sessionID, event->requestID,
+            QxtJSON::stringify(res).toUtf8() + "\r\n");
+    postEvent(err);
+}
+
 /*!
     Returns the current absolute url of this service depending on the request \a event.
  */

src/web/qxtwebjsonrpcservice.h

@@ -35,7 +35,6 @@
 #include "qxtabstractwebservice.h"
 #include <QUrl>
 
-
 class QXT_WEB_EXPORT QxtWebJsonRPCService : public QxtAbstractWebService
 {
     Q_OBJECT
@@ -44,6 +43,8 @@ public:
     virtual ~QxtWebJsonRPCService();
 
 protected:
+    void throwRPCError(QVariant error);
+
     QUrl self(QxtWebRequestEvent* event);
     virtual void pageRequestedEvent(QxtWebRequestEvent* event);
     virtual void functionInvokedEvent(QxtWebRequestEvent* event);

src/web/qxtwebjsonrpcservice_p.h

@@ -54,6 +54,10 @@ public:
     };
     QMap<QByteArray, Method> methods;
 
+    QxtWebRequestEvent *currentRequest;
+    QVariant currentRequestId;
+    bool requestCanceled;
+
 public slots:
     void readFinished();
     void handle(QxtWebContent *);