Allow any number of changes to the table schema in one alterTable call

In the Edit Table dialog we used to call our alterTable function (which
works around SQLite's missing full ALTER TABLE support by - besided
other things - copying all the data of the table) for pretty much every
change immediately. This was taking a lot of time for larger tables.

Our alterTable function allowed any number of changes if they affect
only one field of the table at once. So we could have reduced the number
of calls a lot by just using that capability. Instead however, this
commit improves the alterTable function to make possible transforming a
table completely in just one call. It does so by taking the new table
schema and using that without further modification. It also takes a new
parameter to keep track of what column in the old table becomes what
column in the new table, so the data can be preserved.

This commit obviously also changes the Edit Table dialog to make proper
use of the new features. This means that whatever changes you make to a
table, you will only have to wait once until for the alterTable call,
and that's when clicking the OK button.

See issue #1444.

src/EditTableDialog.cpp

@@ -37,6 +37,10 @@ EditTableDialog::EditTableDialog(DBBrowserDB& db, const sqlb::ObjectIdentifier&
         m_table = *(pdb.getObjectByName<sqlb::Table>(curTable));
         ui->labelEditWarning->setVisible(!m_table.fullyParsed());
 
+        // Initialise the list of tracked columns for table layout changes
+        for(const auto& field : m_table.fields)
+            trackColumns[field.name()] = field.name();
+
         // Set without rowid checkbox and schema dropdown. No need to trigger any events here as we're only loading a table exactly as it is stored by SQLite, so no need
         // for error checking etc.
         ui->checkWithoutRowid->blockSignals(true);
@@ -57,9 +61,6 @@ EditTableDialog::EditTableDialog(DBBrowserDB& db, const sqlb::ObjectIdentifier&
     // And create a savepoint
     pdb.setSavepoint(m_sRestorePointName);
 
-    // Check now if foreign keys are enabled so we don't have to query this later again and again
-    m_bForeignKeysEnabled = (pdb.getPragma("foreign_keys") == "1");
-
     // Update UI
     ui->editTableName->setText(curTable.name());
     updateColumnWidth();
@@ -170,14 +171,11 @@ void EditTableDialog::accept()
     } else {
         // Editing of old table
 
-        // Rename table if necessary
-        if(ui->editTableName->text() != curTable.name())
+        // Apply all changes to the actual table in the database
+        if(!pdb.alterTable(curTable, m_table, trackColumns, ui->comboSchema->currentText()))
         {
-            if(!pdb.renameTable(ui->comboSchema->currentText(), curTable.name(), ui->editTableName->text()))
-            {
-                QMessageBox::warning(this, QApplication::applicationName(), pdb.lastError());
-                return;
-            }
+            QMessageBox::warning(this, QApplication::applicationName(), pdb.lastError());
+            return;
         }
     }
 
@@ -214,13 +212,8 @@ void EditTableDialog::checkInput()
         const auto& fields = m_table.fields;
         for(const sqlb::Field& f : fields) {
             auto fk = std::dynamic_pointer_cast<sqlb::ForeignKeyClause>(m_table.constraint({f.name()}, sqlb::Constraint::ForeignKeyConstraintType));
-            if(fk) {
-                if (oldTableName == fk->table()) {
-                    fk->setTable(normTableName);
-                    if(!m_bForeignKeysEnabled)
-                        pdb.alterTable(curTable, m_table, f.name(), &f, 0);
-                }
-            }
+            if(fk && oldTableName == fk->table())
+                fk->setTable(normTableName);
         }
 
         populateFields();
@@ -238,16 +231,15 @@ void EditTableDialog::updateTypes(QObject *object)
         QString type = typeBox->currentText();
         QString column = typeBox->property("column").toString();
 
-        size_t index;
-        for(index=0; index < m_table.fields.size(); ++index)
+        for(size_t index=0; index < m_table.fields.size(); ++index)
         {
             if(m_table.fields.at(index).name() == column)
+            {
+                m_table.fields.at(index).setType(type);
                 break;
+            }
         }
 
-        m_table.fields.at(index).setType(type);
-        if(!m_bNewTable)
-            pdb.alterTable(curTable, m_table, column, &m_table.fields[index]);
         checkInput();
     }
 }
@@ -272,7 +264,6 @@ void EditTableDialog::itemChanged(QTreeWidgetItem *item, int column)
     if(index < static_cast<int>(m_table.fields.size()))
     {
         sqlb::Field& field = m_table.fields.at(index);
-        bool callRenameColumn = false;
         QString oldFieldName = field.name();
 
         switch(column)
@@ -328,8 +319,16 @@ void EditTableDialog::itemChanged(QTreeWidgetItem *item, int column)
             field.setName(item->text(column));
             m_table.renameKeyInAllConstraints(oldFieldName, item->text(column));
             qobject_cast<QComboBox*>(ui->treeWidget->itemWidget(item, kType))->setProperty("column", item->text(column));
+
+            // Update the field name in the map of old column names to new column names
             if(!m_bNewTable)
-                callRenameColumn = true;
+            {
+                for(const auto& key : trackColumns)
+                {
+                    if(trackColumns[key] == oldFieldName)
+                        trackColumns[key] = field.name();
+                }
+            }
             } break;
         case kType:
             // see updateTypes() SLOT
@@ -362,8 +361,6 @@ void EditTableDialog::itemChanged(QTreeWidgetItem *item, int column)
             } else {
                 item->setCheckState(kAutoIncrement, Qt::Unchecked);
             }
-            if(!m_bNewTable)
-                callRenameColumn = true;
         }
         break;
         case kNotNull:
@@ -395,8 +392,6 @@ void EditTableDialog::itemChanged(QTreeWidgetItem *item, int column)
                 }
             }
             field.setNotNull(item->checkState(column) == Qt::Checked);
-            if(!m_bNewTable)
-                callRenameColumn = true;
         }
         break;
         case kAutoIncrement:
@@ -446,9 +441,6 @@ void EditTableDialog::itemChanged(QTreeWidgetItem *item, int column)
                 }
             }
             field.setAutoIncrement(ischecked);
-
-            if(!m_bNewTable)
-                callRenameColumn = true;
         }
         break;
         case kUnique:
@@ -484,9 +476,6 @@ void EditTableDialog::itemChanged(QTreeWidgetItem *item, int column)
                 }
             }
             field.setUnique(item->checkState(column) == Qt::Checked);
-
-            if(!m_bNewTable)
-                callRenameColumn = true;
         }
         break;
         case kDefault:
@@ -517,28 +506,15 @@ void EditTableDialog::itemChanged(QTreeWidgetItem *item, int column)
                 }
             }
             field.setDefaultValue(new_value);
-            if(!m_bNewTable)
-                callRenameColumn = true;
         }
         break;
         case kCheck:
             field.setCheck(item->text(column));
-            if(!m_bNewTable)
-                callRenameColumn = true;
             break;
         case kForeignKey:
             // handled in delegate
-
-            if(!m_bNewTable)
-                callRenameColumn = true;
             break;
         }
-
-        if(callRenameColumn)
-        {
-            if(!pdb.alterTable(curTable, m_table, oldFieldName, &field))
-                QMessageBox::warning(this, qApp->applicationName(), tr("Modifying this column failed. Error returned from database:\n%1").arg(pdb.lastError()));
-        }
     }
 
     checkInput();
@@ -590,9 +566,9 @@ void EditTableDialog::addField()
     // add field to table object
     m_table.fields.emplace_back(tbitem->text(kName), typeBox->currentText());
 
-    // Actually add the new column to the table if we're editing an existing table
+    // Add the new column to the list of tracked columns to indicate it has been added
     if(!m_bNewTable)
-        pdb.addColumn(curTable, m_table.fields.back());
+        trackColumns.insert(QString(), tbitem->text(kName));
 
     checkInput();
 }
@@ -603,33 +579,27 @@ void EditTableDialog::removeField()
     if(!ui->treeWidget->currentItem())
         return;
 
-    // Are we creating a new table or editing an old one?
-    if(m_bNewTable)
+    // If we are editing an existing table, ask the user for confirmation
+    if(!m_bNewTable)
     {
-        // Creating a new one
-
-        // Just delete that item. At this point there is no DB table to edit or data to be lost anyway
-        m_table.fields.erase(m_table.fields.begin() + ui->treeWidget->indexOfTopLevelItem(ui->treeWidget->currentItem()));
-        m_table.removeKeyFromAllConstraints(ui->treeWidget->currentItem()->text(kName));
-        delete ui->treeWidget->currentItem();
-    } else {
-        // Editing an old one
-
-        // Ask user whether he really wants to delete that column
         QString msg = tr("Are you sure you want to delete the field '%1'?\nAll data currently stored in this field will be lost.").arg(ui->treeWidget->currentItem()->text(0));
-        if(QMessageBox::warning(this, QApplication::applicationName(), msg, QMessageBox::Yes | QMessageBox::No, QMessageBox::No) == QMessageBox::Yes)
+        if(QMessageBox::warning(this, QApplication::applicationName(), msg, QMessageBox::Yes | QMessageBox::No, QMessageBox::No) == QMessageBox::No)
+            return;
+
+        // Update the map of tracked columns to indicate the column is deleted
+        QString name = ui->treeWidget->currentItem()->text(0);
+        for(const auto& key : trackColumns)
         {
-            if(!pdb.alterTable(curTable, m_table, ui->treeWidget->currentItem()->text(0), nullptr))
-            {
-                QMessageBox::warning(nullptr, QApplication::applicationName(), pdb.lastError());
-            } else {
-                //relayout
-                m_table = *(pdb.getObjectByName<sqlb::Table>(curTable));
-                populateFields();
-            }
+            if(trackColumns[key] == name)
+                trackColumns[key] = QString();
         }
     }
 
+    // Just delete that item. At this point there is no DB table to edit or data to be lost anyway
+    m_table.fields.erase(m_table.fields.begin() + ui->treeWidget->indexOfTopLevelItem(ui->treeWidget->currentItem()));
+    m_table.removeKeyFromAllConstraints(ui->treeWidget->currentItem()->text(kName));
+    delete ui->treeWidget->currentItem();
+
     checkInput();
 }
 
@@ -665,54 +635,27 @@ void EditTableDialog::moveCurrentField(bool down)
     int currentRow = ui->treeWidget->currentIndex().row();
     int newRow = currentRow + (down ? 1 : -1);
 
-    // Are we creating a new table or editing an old one?
-    if(m_bNewTable)
-    {
-        // Creating a new one
+    // Save the combobox first by making a copy
+    QComboBox* oldCombo = qobject_cast<QComboBox*>(ui->treeWidget->itemWidget(ui->treeWidget->topLevelItem(currentRow), kType));
+    QComboBox* newCombo = new QComboBox(ui->treeWidget);
+    newCombo->setProperty("column", oldCombo->property("column"));
+    newCombo->installEventFilter(this);
+    connect(newCombo, SIGNAL(currentIndexChanged(int)), this, SLOT(updateTypes()));
+    newCombo->setEditable(true);
+    for(int i=0; i < oldCombo->count(); ++i)
+        newCombo->addItem(oldCombo->itemText(i));
+    newCombo->setCurrentIndex(oldCombo->currentIndex());
 
-        // Save the combobox first by making a copy
-        QComboBox* oldCombo = qobject_cast<QComboBox*>(ui->treeWidget->itemWidget(ui->treeWidget->topLevelItem(currentRow), kType));
-        QComboBox* newCombo = new QComboBox(ui->treeWidget);
-        newCombo->setProperty("column", oldCombo->property("column"));
-        newCombo->installEventFilter(this);
-        connect(newCombo, SIGNAL(currentIndexChanged(int)), this, SLOT(updateTypes()));
-        newCombo->setEditable(true);
-        for(int i=0; i < oldCombo->count(); ++i)
-            newCombo->addItem(oldCombo->itemText(i));
-        newCombo->setCurrentIndex(oldCombo->currentIndex());
+    // Now, just remove the item and insert it at it's new position, then restore the combobox
+    QTreeWidgetItem* item = ui->treeWidget->takeTopLevelItem(currentRow);
+    ui->treeWidget->insertTopLevelItem(newRow, item);
+    ui->treeWidget->setItemWidget(item, kType, newCombo);
 
-        // Now, just remove the item and insert it at it's new position, then restore the combobox
-        QTreeWidgetItem* item = ui->treeWidget->takeTopLevelItem(currentRow);
-        ui->treeWidget->insertTopLevelItem(newRow, item);
-        ui->treeWidget->setItemWidget(item, kType, newCombo);
+    // Select the old item at its new position
+    ui->treeWidget->setCurrentIndex(ui->treeWidget->currentIndex().sibling(newRow, 0));
 
-        // Select the old item at its new position
-        ui->treeWidget->setCurrentIndex(ui->treeWidget->currentIndex().sibling(newRow, 0));
-
-        // Finally update the table SQL
-        std::swap(m_table.fields[newRow], m_table.fields[currentRow]);
-    } else {
-        // Editing an old one
-
-        // Move the actual column
-        if(!pdb.alterTable(
-                    curTable,
-                    m_table,
-                    ui->treeWidget->currentItem()->text(0),
-                    &m_table.fields[ui->treeWidget->indexOfTopLevelItem(ui->treeWidget->currentItem())],
-                    (down ? 1 : -1)
-                ))
-        {
-            QMessageBox::warning(nullptr, QApplication::applicationName(), pdb.lastError());
-        } else {
-            // Reload table SQL
-            m_table = *(pdb.getObjectByName<sqlb::Table>(curTable));
-            populateFields();
-
-            // Select old item at new position
-            ui->treeWidget->setCurrentIndex(ui->treeWidget->indexAt(QPoint(1, 1)).sibling(newRow, 0));
-        }
-    }
+    // Finally update the table SQL
+    std::swap(m_table.fields[newRow], m_table.fields[currentRow]);
 
     // Update the SQL preview
     updateSqlText();
@@ -748,33 +691,10 @@ void EditTableDialog::setWithoutRowid(bool without_rowid)
 
     // Update the SQL preview
     updateSqlText();
-
-    // Update table if we're editing an existing table
-    if(!m_bNewTable)
-    {
-        if(!pdb.alterTable(curTable, m_table, QString(), nullptr, 0))
-        {
-            QMessageBox::warning(this, QApplication::applicationName(),
-                                 tr("Setting the rowid column for the table failed. Error message:\n%1").arg(pdb.lastError()));
-        }
-    }
 }
 
-void EditTableDialog::changeSchema(const QString& schema)
+void EditTableDialog::changeSchema(const QString& /*schema*/)
 {
     // Update the SQL preview
     updateSqlText();
-
-    // Update table if we're editing an existing table
-    if(!m_bNewTable)
-    {
-        if(pdb.alterTable(curTable, m_table, QString(), nullptr, 0, schema))
-        {
-            // Save the new schema name to use it from now on
-            curTable.setSchema(schema);
-        } else {
-            QMessageBox::warning(this, QApplication::applicationName(), tr("Changing the table schema failed. Error message:\n%1").arg(pdb.lastError()));
-            ui->comboSchema->setCurrentText(curTable.schema()); // Set it back to the original schema
-        }
-    }
 }