QSqlTableModel::setData()/setRecord(): fix incorrect row

For OnFieldChange and OnRowChange, before submitting new changes,
setData() and setRecord() attempt to submit pending changes and
revert them upon failure. However, they fail to consider that
reverting pending insertions removes rows from the model. As a
result, the new change can be applied to a row higher than intended.

One possible solution would be to adjust the targetted index for the
removed rows, so that the intended row is affected by the new change.
But this still causes the strange editing experience as rows jump
up just as they are being edited.

It does not seem right in the first place for the model to initiate
reverting changes. It should be up to the application to decide what
to do when data cannot be committed. In particular, setData() and
setRecord() should not have the side effect of reverting already
pending changes.

The chosen solution is simply to refuse new changes that don't make
sense for the edit strategy. For OnFieldChange, flag() will
indicate read-only when editing is blocked by a pending change.

Since setData() and setRecord() submit data immediately for
OnFieldChange, it no longer makes sense to resubmit changes
automatically before a new change.

For OnRowChange, setData() keeps the behavior of automatically
submitting a pending row before starting on a new row. This is
historical behavior and is probably motivated by the fact that
QTableView does not automatically call submit() when editing leaves a
row. The obvious shortcoming of this is that the last row to be edited
will not be submitted automatically. It also prevents us from flagging
rows other than the pending row as read-only.

For OnRowChange, setRecord(), being row-oriented by nature, should
submit the change immediately rather than waiting for the next call
to setRecord(). This makes setRecord() consistent with insertRecord().

Change-Id: Icb4019d8b7c53a7ee48f8121a7a525e8bc35d523
Reviewed-by: Honglei Zhang <honglei.zhang@nokia.com>

1 files changed, 38 insertions, 25 deletions

diff --git a/src/sql/models/qsqltablemodel.cpp b/src/sql/models/qsqltablemodel.cpp
index 30e01b06e7..a001b262de 100644
--- a/src/sql/models/qsqltablemodel.cpp
+++ b/src/sql/models/qsqltablemodel.cpp
@@ -511,8 +511,19 @@ bool QSqlTableModel::isDirty(const QModelIndex &index) const
 
 /*!
     Sets the data for the item \a index for the role \a role to \a
-    value. Depending on the edit strategy, the value might be applied
-    to the database at once or cached in the model.
+    value.
+
+    For edit strategy OnFieldChange, an index may receive a change
+    only if no other index has a cached change. Changes are
+    submitted immediately. However, rows that have not yet been
+    inserted in the database may be freely changed and and are not
+    submitted automatically.
+
+    For OnRowChange, the first change to a row will cause cached
+    operations on other rows to be submitted. If submitting fails,
+    the new change is rejected.
+
+    Submitted changes are not reverted upon failure.
 
     Returns true if the value could be set or false on error, for
     example if \a index is out of bounds.
@@ -534,11 +545,16 @@ bool QSqlTableModel::setData(const QModelIndex &index, const QVariant &value, in
     if (d->cache.value(index.row()).op() == QSqlTableModelPrivate::Delete)
         return false;
 
-    if (d->strategy == OnFieldChange && d->cache.value(index.row()).op() != QSqlTableModelPrivate::Insert) {
-        revertAll();
-    } else if (d->strategy == OnRowChange && !d->cache.isEmpty() && !d->cache.contains(index.row())) {
-        submit();
-        revertAll();
+    if (d->strategy == OnFieldChange) {
+        if (d->cache.value(index.row()).op() != QSqlTableModelPrivate::Insert
+            && !isDirty(index) && isDirty())
+            return false;
+    }
+    else if (d->strategy == OnRowChange) {
+        if (d->cache.value(index.row()).submitted()) {
+            if (!submit())
+                return false;
+        }
     }
 
     QSqlTableModelPrivate::ModifiedRow &row = d->cache[index.row()];
@@ -1132,25 +1148,20 @@ bool QSqlTableModel::insertRows(int row, int count, const QModelIndex &parent)
     Returns true if the record could be inserted, otherwise false.
 
     Changes are submitted immediately for OnFieldChange and
-    OnRowChange. Note the contrast with setRecord() in respect to
-    OnRowChange.
+    OnRowChange. Failure does not leave a new row in the model.
 
     \sa insertRows(), removeRows(), setRecord()
 */
 bool QSqlTableModel::insertRecord(int row, const QSqlRecord &record)
 {
-    Q_D(QSqlTableModel);
     if (row < 0)
         row = rowCount();
     if (!insertRow(row, QModelIndex()))
         return false;
     if (!setRecord(row, record)) {
-        if (d->strategy == OnManualSubmit)
-            revertRow(row);
+        revertRow(row);
         return false;
     }
-    if (d->strategy == OnFieldChange || d->strategy == OnRowChange)
-        return submit();
     return true;
 }
 
@@ -1240,6 +1251,11 @@ Qt::ItemFlags QSqlTableModel::flags(const QModelIndex &index) const
         return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
     if (d->cache.value(index.row()).op() == QSqlTableModelPrivate::Delete)
         return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
+    if (d->strategy == OnFieldChange
+        && d->cache.value(index.row()).op() != QSqlTableModelPrivate::Insert
+        && !isDirty(index) && isDirty())
+        return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
+
     return Qt::ItemIsSelectable | Qt::ItemIsEnabled | Qt::ItemIsEditable;
 }
 
@@ -1247,15 +1263,14 @@ Qt::ItemFlags QSqlTableModel::flags(const QModelIndex &index) const
     Sets the values at the specified \a row to the values of \a
     record for fields where generated flag is true.
 
+    For edit strategies OnFieldChange and OnRowChange, a row may
+    receive a change only if no other row has a cached change.
+    Changes are submitted immediately. Submitted changes are not
+    reverted upon failure.
+
     Returns true if all the values could be set; otherwise returns
     false.
 
-    The edit strategy affects automatic submitting.
-    With OnFieldChange, setRecord() commits its changed row.
-    With OnRowChange, setRecord() does not commit its changed row,
-    but making a change to another row causes previous changes to
-    be submitted.
-
     \sa record(), editStrategy()
 */
 bool QSqlTableModel::setRecord(int row, const QSqlRecord &values)
@@ -1271,10 +1286,8 @@ bool QSqlTableModel::setRecord(int row, const QSqlRecord &values)
     if (d->cache.value(row).op() == QSqlTableModelPrivate::Delete)
         return false;
 
-    if (d->strategy == OnFieldChange && d->cache.value(row).op() != QSqlTableModelPrivate::Insert)
-        revertAll();
-    else if (d->strategy == OnRowChange && !d->cache.isEmpty() && !d->cache.contains(row))
-        submit();
+    if (d->strategy != OnManualSubmit && d->cache.value(row).submitted() && isDirty())
+        return false;
 
     // Check field names and remember mapping
     typedef QMap<int, int> Map;
@@ -1301,7 +1314,7 @@ bool QSqlTableModel::setRecord(int row, const QSqlRecord &values)
     if (columnCount())
         emit dataChanged(createIndex(row, 0), createIndex(row, columnCount() - 1));
 
-    if (d->strategy == OnFieldChange)
+    if (d->strategy != OnManualSubmit)
         return submit();
 
     return true;