Reconnect to database after network failure

It's more difficult than I thought. It seems you need a failed query until
libpq notices that the connection is lost. Implement reconnect at the
very bottom of the slide time to get it back as soon as possible.

I have no idea though what it does to cloned connections. Also, if no
slide show is running, it'll never reconnect.

It works when I down the database, maybe create a Helper function for
this...

1 files changed, 8 insertions, 5 deletions

diff --git a/picfilesmodel.cpp b/picfilesmodel.cpp
index 8ea4442..f0d02dc 100644
--- a/picfilesmodel.cpp
+++ b/picfilesmodel.cpp
@@ -172,9 +172,6 @@ SmTreeItem *PicFilesModel::mappingTreeFromFile(int fileId){
         return 0;
     }
     SmTreeItem *retval = new SmTreeItem(2);
-    if(!mDb.isOpen()){
-        mDb.open();
-    }
     QSqlQuery mpq(mDb);
     mpq.prepare("SELECT imapping_parents_id, iparent_id, tdescription_name, mapping_parents.idescription_id FROM mapping_parents, mapping_description WHERE imapping_parents_id = :id AND mapping_parents.idescription_id = mapping_description.idescription_id");
     foreach(int pId, parentIds){
@@ -295,8 +292,14 @@ QList<int> PicFilesModel::mappingPIdsFromFiles(QList<int> fileIds){
     foreach(int id, fileIds){
         idList << QString::number(id);
     }
-    QString query = mMappingsQS.arg(idList.join(","));
-    QSqlQuery q(query, mDb);
+    QString qTempl = QString(mMappingsQS.arg(idList.join(",")));
+    QSqlQuery q(mDb);
+    q.prepare(qTempl);
+    if(!q.exec()){
+        mDb.close();
+        mDb.open();
+        return QList<int>();
+    }
     QList<int> retval;
     while(q.next()){
         retval << q.value(0).toInt();