QSql*Model: add SQL syntax helper
authorMark Brand <mabrand@mabrand.nl>
Wed, 14 Mar 2012 09:22:50 +0000 (10:22 +0100)
committerQt by Nokia <qt-info@nokia.com>
Thu, 22 Mar 2012 15:13:21 +0000 (16:13 +0100)
Change-Id: Ia53e30d7a2f2bb5b4f76c32fcf0fe526d1e4ab51
Reviewed-by: Honglei Zhang <honglei.zhang@nokia.com>
src/sql/models/qsqlquerymodel_p.h
src/sql/models/qsqlrelationaltablemodel.cpp
src/sql/models/qsqltablemodel.cpp
src/sql/models/qsqltablemodel_p.h

index b5eb60c..6e0349f 100644 (file)
@@ -82,6 +82,45 @@ public:
     QVarLengthArray<int, 56> colOffsets; // used to calculate indexInQuery of columns
 };
 
+// helpers for building SQL expressions
+class QSqlQueryModelSql
+{
+public:
+    // SQL keywords
+    inline const static QLatin1String as() { return QLatin1String("AS"); }
+    inline const static QLatin1String asc() { return QLatin1String("ASC"); }
+    inline const static QLatin1String comma() { return QLatin1String(","); }
+    inline const static QLatin1String desc() { return QLatin1String("DESC"); }
+    inline const static QLatin1String eq() { return QLatin1String("="); }
+    // "and" is a C++ keyword
+    inline const static QLatin1String et() { return QLatin1String("AND"); }
+    inline const static QLatin1String from() { return QLatin1String("FROM"); }
+    inline const static QLatin1String leftJoin() { return QLatin1String("LEFT JOIN"); }
+    inline const static QLatin1String on() { return QLatin1String("ON"); }
+    inline const static QLatin1String orderBy() { return QLatin1String("ORDER BY"); }
+    inline const static QLatin1String parenClose() { return QLatin1String(")"); }
+    inline const static QLatin1String parenOpen() { return QLatin1String("("); }
+    inline const static QLatin1String select() { return QLatin1String("SELECT"); }
+    inline const static QLatin1String sp() { return QLatin1String(" "); }
+    inline const static QLatin1String where() { return QLatin1String("WHERE"); }
+
+    // Build expressions based on key words
+    inline const static QString as(const QString &a, const QString &b) { return b.isEmpty() ? a : concat(concat(a, as()), b); }
+    inline const static QString asc(const QString &s) { return concat(s, asc()); }
+    inline const static QString comma(const QString &a, const QString &b) { return a.isEmpty() ? b : b.isEmpty() ? a : QString(a).append(comma()).append(b); }
+    inline const static QString concat(const QString &a, const QString &b) { return a.isEmpty() ? b : b.isEmpty() ? a : QString(a).append(sp()).append(b); }
+    inline const static QString desc(const QString &s) { return concat(s, desc()); }
+    inline const static QString eq(const QString &a, const QString &b) { return QString(a).append(eq()).append(b); }
+    inline const static QString et(const QString &a, const QString &b) { return a.isEmpty() ? b : b.isEmpty() ? a : concat(concat(a, et()), b); }
+    inline const static QString from(const QString &s) { return concat(from(), s); }
+    inline const static QString leftJoin(const QString &s) { return concat(leftJoin(), s); }
+    inline const static QString on(const QString &s) { return concat(on(), s); }
+    inline const static QString orderBy(const QString &s) { return s.isEmpty() ? s : concat(orderBy(), s); }
+    inline const static QString paren(const QString &s) { return s.isEmpty() ? s : parenOpen() + s + parenClose(); }
+    inline const static QString select(const QString &s) { return concat(select(), s); }
+    inline const static QString where(const QString &s) { return s.isEmpty() ? s : concat(where(), s); }
+};
+
 QT_END_NAMESPACE
 
 #endif // QSQLQUERYMODEL_P_H
index b5d98d5..0387e56 100644 (file)
 
 QT_BEGIN_NAMESPACE
 
+class QSqlRelationalTableModelSql: public QSqlTableModelSql
+{
+public:
+    inline const static QString relTablePrefix(int i) { return QString::number(i).prepend(QLatin1String("relTblAl_")); }
+};
+
+typedef QSqlRelationalTableModelSql Sql;
+
 /*!
     \class QSqlRelation
     \brief The QSqlRelation class stores information about an SQL foreign key.
@@ -272,18 +280,6 @@ public:
     QSqlRelationalTableModel::JoinMode joinMode;
 };
 
-static void qAppendWhereClause(QString &query, const QString &clause1, const QString &clause2)
-{
-    if (clause1.isEmpty() && clause2.isEmpty())
-        return;
-    if (clause1.isEmpty() || clause2.isEmpty())
-        query.append(QLatin1String(" WHERE (")).append(clause1).append(clause2);
-    else
-        query.append(QLatin1String(" WHERE (")).append(clause1).append(
-                        QLatin1String(") AND (")).append(clause2);
-    query.append(QLatin1String(") "));
-}
-
 void QSqlRelationalTableModelPrivate::clearChanges()
 {
     for (int i = 0; i < relations.count(); ++i) {
@@ -571,12 +567,12 @@ QString QSqlRelationalTableModel::selectStatement() const
 
     QString fList;
     QString conditions;
-    QString from = tableName();
+    QString from = Sql::from(tableName());
     for (int i = 0; i < d->baseRec.count(); ++i) {
         QSqlRelation relation = d->relations.value(i).rel;
         const QString tableField = d->fullyQualifiedFieldName(tableName(), d->db.driver()->escapeIdentifier(d->baseRec.fieldName(i), QSqlDriver::FieldName));
         if (relation.isValid()) {
-            const QString relTableAlias = QString::fromLatin1("relTblAl_%1").arg(i);
+            const QString relTableAlias = Sql::relTablePrefix(i);
             QString displayTableField = d->fullyQualifiedFieldName(relTableAlias, relation.displayColumn());
 
             // Duplicate field names must be aliased
@@ -587,55 +583,37 @@ QString QSqlRelationalTableModel::selectStatement() const
                 QString displayColumn = relation.displayColumn();
                 if (d->db.driver()->isIdentifierEscaped(displayColumn, QSqlDriver::FieldName))
                     displayColumn = d->db.driver()->stripDelimiters(displayColumn, QSqlDriver::FieldName);
-                displayTableField.append(QString::fromLatin1(" AS %1_%2_%3").arg(relTableName).arg(displayColumn).arg(fieldNames.value(fieldList[i])));
+                const QString alias = QString::fromLatin1("%1_%2_%3").arg(relTableName).arg(displayColumn).arg(fieldNames.value(fieldList[i]));
+                displayTableField = Sql::as(displayTableField, alias);
                 --fieldNames[fieldList[i]];
             }
 
-            if (!fList.isEmpty())
-                fList.append(QLatin1String(", "));
-            fList.append(displayTableField);
+            fList = Sql::comma(fList, displayTableField);
 
             // Join related table
-            const QString tblexpr = relation.tableName().append(QLatin1Char(' ')).append(relTableAlias);
+            const QString tblexpr = Sql::concat(relation.tableName(), relTableAlias);
             const QString relTableField = d->fullyQualifiedFieldName(relTableAlias, relation.indexColumn());
-            const QString cond = tableField + QLatin1String(" = ") + relTableField;
+            const QString cond = Sql::eq(tableField, relTableField);
             if (d->joinMode == QSqlRelationalTableModel::InnerJoin) {
                 // FIXME: InnerJoin code is known to be broken.
                 // Use LeftJoin mode if you want correct behavior.
-                from.append(QLatin1String(", ")).append(tblexpr);
-                if (!conditions.isEmpty())
-                    conditions.append(QLatin1String(" AND "));
-                conditions.append(cond);
+                from = Sql::comma(from, tblexpr);
+                conditions = Sql::et(conditions, cond);
             } else {
-                from.append(QLatin1String(" LEFT JOIN ")).append(tblexpr);
-                from.append(QLatin1String(" ON ")).append(cond);
+                from = Sql::concat(from, Sql::leftJoin(tblexpr));
+                from = Sql::concat(from, Sql::on(cond));
             }
         } else {
-            if (!fList.isEmpty())
-                fList.append(QLatin1String(", "));
-            fList.append(tableField);
+            fList = Sql::comma(fList, tableField);
         }
     }
 
     if (fList.isEmpty())
         return QString();
 
-    QString query = query.append(QLatin1String("SELECT "));
-    query.append(fList).append(QLatin1String(" FROM ")).append(from);
-
-    if (d->joinMode == QSqlRelationalTableModel::InnerJoin) {
-        qAppendWhereClause(query, conditions, filter());
-    } else if (!filter().isEmpty()) {
-        query.append(QLatin1String(" WHERE ("));
-        query.append(filter());
-        query.append(QLatin1String(")"));
-    }
-
-    QString orderBy = orderByClause();
-    if (!orderBy.isEmpty())
-        query.append(QLatin1Char(' ')).append(orderBy);
-
-    return query;
+    const QString stmt = Sql::concat(Sql::select(fList), from);
+    const QString where = Sql::where(Sql::et(Sql::paren(conditions), Sql::paren(filter())));
+    return Sql::concat(Sql::concat(stmt, where), orderByClause());
 }
 
 /*!
@@ -777,11 +755,9 @@ QString QSqlRelationalTableModel::orderByClause() const
     if (!rel.isValid())
         return QSqlTableModel::orderByClause();
 
-    QString s = QLatin1String("ORDER BY ");
-    s.append(d->fullyQualifiedFieldName(QLatin1String("relTblAl_") + QString::number(d->sortColumn),
-                                        rel.displayColumn()));
-    s += d->sortOrder == Qt::AscendingOrder ? QLatin1String(" ASC") : QLatin1String(" DESC");
-    return s;
+    QString f = d->fullyQualifiedFieldName(Sql::relTablePrefix(d->sortColumn), rel.displayColumn());
+    f = d->sortOrder == Qt::AscendingOrder ? Sql::asc(f) : Sql::desc(f);
+    return Sql::orderBy(f);
 }
 
 /*!
index 0e5eba1..20d2be3 100644 (file)
@@ -55,6 +55,8 @@
 
 QT_BEGIN_NAMESPACE
 
+typedef QSqlTableModelSql Sql;
+
 /*! \internal
     Populates our record with values.
 */
@@ -411,8 +413,9 @@ bool QSqlTableModel::selectRow(int row)
                                               d->tableName,
                                               d->primaryValues(row),
                                               false);
-    if (d->filter.startsWith(QLatin1String("WHERE "), Qt::CaseInsensitive))
-        d->filter.remove(0, 6);
+    static const QString wh = Sql::where() + Sql::sp();
+    if (d->filter.startsWith(wh, Qt::CaseInsensitive))
+        d->filter.remove(0, wh.length());
     const QString stmt = selectStatement();
     d->sortColumn = table_sort_col;
     d->filter = table_filter;
@@ -589,8 +592,8 @@ bool QSqlTableModel::updateRowInTable(int row, const QSqlRecord &values)
 
     const QSqlRecord whereValues = d->primaryValues(row);
     const bool prepStatement = d->db.driver()->hasFeature(QSqlDriver::PreparedQueries);
-    QString stmt = d->db.driver()->sqlStatement(QSqlDriver::UpdateStatement, d->tableName,
-                                                rec, prepStatement);
+    const QString stmt = d->db.driver()->sqlStatement(QSqlDriver::UpdateStatement, d->tableName,
+                                                     rec, prepStatement);
     const QString where = d->db.driver()->sqlStatement(QSqlDriver::WhereStatement, d->tableName,
                                                        whereValues, prepStatement);
 
@@ -599,9 +602,8 @@ bool QSqlTableModel::updateRowInTable(int row, const QSqlRecord &values)
                                  QSqlError::StatementError);
         return false;
     }
-    stmt.append(QLatin1Char(' ')).append(where);
 
-    return d->exec(stmt, prepStatement, rec, whereValues);
+    return d->exec(Sql::concat(stmt, where), prepStatement, rec, whereValues);
 }
 
 
@@ -656,10 +658,10 @@ bool QSqlTableModel::deleteRowFromTable(int row)
 
     const QSqlRecord whereValues = d->primaryValues(row);
     const bool prepStatement = d->db.driver()->hasFeature(QSqlDriver::PreparedQueries);
-    QString stmt = d->db.driver()->sqlStatement(QSqlDriver::DeleteStatement,
-                                                d->tableName,
-                                                QSqlRecord(),
-                                                prepStatement);
+    const QString stmt = d->db.driver()->sqlStatement(QSqlDriver::DeleteStatement,
+                                                      d->tableName,
+                                                      QSqlRecord(),
+                                                      prepStatement);
     const QString where = d->db.driver()->sqlStatement(QSqlDriver::WhereStatement,
                                                        d->tableName,
                                                        whereValues,
@@ -670,9 +672,8 @@ bool QSqlTableModel::deleteRowFromTable(int row)
                              QSqlError::StatementError);
         return false;
     }
-    stmt.append(QLatin1Char(' ')).append(where);
 
-    return d->exec(stmt, prepStatement, QSqlRecord() /* no new values */, whereValues);
+    return d->exec(Sql::concat(stmt, where), prepStatement, QSqlRecord() /* no new values */, whereValues);
 }
 
 /*!
@@ -923,19 +924,16 @@ void QSqlTableModel::setSort(int column, Qt::SortOrder order)
 QString QSqlTableModel::orderByClause() const
 {
     Q_D(const QSqlTableModel);
-    QString s;
     QSqlField f = d->rec.field(d->sortColumn);
     if (!f.isValid())
-        return s;
-        
-    QString table = d->tableName;
+        return QString();
+
     //we can safely escape the field because it would have been obtained from the database
     //and have the correct case
     QString field = d->db.driver()->escapeIdentifier(f.name(), QSqlDriver::FieldName);
-    s.append(QLatin1String("ORDER BY ")).append(table).append(QLatin1Char('.')).append(field);
-    s += d->sortOrder == Qt::AscendingOrder ? QLatin1String(" ASC") : QLatin1String(" DESC");
-
-    return s;
+    field.prepend(QLatin1Char('.')).prepend(d->tableName);
+    field = d->sortOrder == Qt::AscendingOrder ? Sql::asc(field) : Sql::desc(field);
+    return Sql::orderBy(field);
 }
 
 /*!
@@ -958,34 +956,27 @@ int QSqlTableModel::fieldIndex(const QString &fieldName) const
 QString QSqlTableModel::selectStatement() const
 {
     Q_D(const QSqlTableModel);
-    QString query;
     if (d->tableName.isEmpty()) {
         d->error = QSqlError(QLatin1String("No table name given"), QString(),
                              QSqlError::StatementError);
-        return query;
+        return QString();
     }
     if (d->rec.isEmpty()) {
         d->error = QSqlError(QLatin1String("Unable to find table ") + d->tableName, QString(),
                              QSqlError::StatementError);
-        return query;
+        return QString();
     }
 
-    query = d->db.driver()->sqlStatement(QSqlDriver::SelectStatement,
-                                         d->tableName,
-                                         d->rec,
-                                         false);
-    if (query.isEmpty()) {
+    const QString stmt = d->db.driver()->sqlStatement(QSqlDriver::SelectStatement,
+                                                      d->tableName,
+                                                      d->rec,
+                                                      false);
+    if (stmt.isEmpty()) {
         d->error = QSqlError(QLatin1String("Unable to select fields from table ") + d->tableName,
                              QString(), QSqlError::StatementError);
-        return query;
+        return stmt;
     }
-    if (!d->filter.isEmpty())
-        query.append(QLatin1String(" WHERE ")).append(d->filter);
-    QString orderBy(orderByClause());
-    if (!orderBy.isEmpty())
-        query.append(QLatin1Char(' ')).append(orderBy);
-
-    return query;
+    return Sql::concat(Sql::concat(stmt, Sql::where(d->filter)), orderByClause());
 }
 
 /*!
index 20ca63a..2bbb4e1 100644 (file)
@@ -191,6 +191,11 @@ public:
     CacheMap cache;
 };
 
+class QSqlTableModelSql: public QSqlQueryModelSql
+{
+public:
+};
+
 QT_END_NAMESPACE
 
 #endif // QSQLTABLEMODEL_P_H