Rework mssql driver to support the new iterator model

src/providers/CMakeLists.txt

@@ -9,7 +9,7 @@ ADD_SUBDIRECTORY(delimitedtext)
 ADD_SUBDIRECTORY(osm)
 #ADD_SUBDIRECTORY(sqlanywhere)   # TODO: enable when migrated to new api
 ADD_SUBDIRECTORY(gdal)
-#ADD_SUBDIRECTORY(mssql)         # TODO: enable when migrated to new api
+ADD_SUBDIRECTORY(mssql)
 ADD_SUBDIRECTORY(ows)
 ADD_SUBDIRECTORY(wcs)
 ADD_SUBDIRECTORY(gpx)

src/providers/mssql/CMakeLists.txt

@@ -1,7 +1,7 @@
+
+SET (MSSQL_SRCS qgsmssqlprovider.cpp qgsmssqlgeometryparser.cpp qgsmssqlsourceselect.cpp qgsmssqltablemodel.cpp qgsmssqlnewconnection.cpp qgsmssqldataitems.cpp qgsmssqlfeatureiterator.cpp)
 
-SET (MSSQL_SRCS qgsmssqlprovider.cpp qgsmssqlgeometryparser.cpp qgsmssqlsourceselect.cpp qgsmssqltablemodel.cpp qgsmssqlnewconnection.cpp qgsmssqldataitems.cpp)
-
-SET (MSSQL_MOC_HDRS qgsmssqlprovider.h qgsmssqlsourceselect.h qgsmssqltablemodel.h qgsmssqlnewconnection.h qgsmssqldataitems.h)
+SET (MSSQL_MOC_HDRS qgsmssqlprovider.h qgsmssqlsourceselect.h qgsmssqltablemodel.h qgsmssqlnewconnection.h qgsmssqldataitems.h qgsmssqlfeatureiterator.h)
 
 ########################################################
 # Build

src/providers/mssql/qgsmssqlfeatureiterator.cpp

@@ -0,0 +1,276 @@
+/***************************************************************************
+                    qgsmssqlfeatureiterator.cpp  -  description
+                             -------------------
+    begin                : 2011-10-08
+    copyright            : (C) 2011 by Tamas Szekeres
+    email                : szekerest at gmail.com
+ ***************************************************************************/
+
+/***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgsmssqlfeatureiterator.h"
+#include "qgsmssqlprovider.h"
+#include "qgslogger.h"
+
+#include <QObject>
+#include <QTextStream>
+
+
+QgsMssqlFeatureIterator::QgsMssqlFeatureIterator( QgsMssqlProvider* provider, const QgsFeatureRequest& request)
+    : QgsAbstractFeatureIterator( request ), mProvider( provider )
+{
+  mIsOpen = false;
+  BuildStatement( request );
+
+  mQuery = NULL;
+
+  if ( mProvider->mQuery.isActive() )
+  {
+    mUseProviderQuery = false;
+    // create a separate database connection if the default query is active
+    QgsDebugMsg( "Creating a separate database connection" );
+    QString id;
+    // QString::sprintf adds 0x prefix
+    id.sprintf("%08p", this);
+    mDatabase = mProvider->mDatabase.cloneDatabase(mProvider->mDatabase, id);
+    if (!mDatabase.open())
+    {
+      QgsDebugMsg( "Failed to open database" );
+      QString msg = mDatabase.lastError().text();
+      QgsDebugMsg( msg );
+      return;
+    }
+    // create sql query
+    mQuery = new QSqlQuery( mDatabase );
+  }
+  else
+  {
+    mUseProviderQuery = true;
+    mQuery = &mProvider->mQuery;   
+  }
+  // start selection
+  rewind();
+}
+
+
+QgsMssqlFeatureIterator::~QgsMssqlFeatureIterator()
+{
+  if (!mUseProviderQuery)
+  {
+    if (mQuery)
+      delete mQuery;
+    mDatabase.close();
+  }
+  else if (mIsOpen)
+      close();
+}
+
+void QgsMssqlFeatureIterator::BuildStatement( const QgsFeatureRequest& request )
+{
+  // build sql statement
+  mStatement = QString( "select " );
+  int fieldCount = 0;
+  mFidCol = -1;
+  mGeometryCol = -1;
+
+  if (!request.subsetOfAttributes().empty())
+  {
+    // subset of attributes has been specified
+    for ( QgsAttributeList::const_iterator it = request.subsetOfAttributes().begin(); it != request.subsetOfAttributes().end(); ++it )
+    {
+      if ( fieldCount != 0 )
+        mStatement += ",";
+      mStatement += "[" + mProvider->mAttributeFields[*it].name() + "]";
+
+      if ( !mProvider->mFidColName.isEmpty() && mProvider->mFidColName == mProvider->mAttributeFields[*it].name() )
+          mFidCol = fieldCount;
+
+      ++fieldCount;
+      mAttributesToFetch.append(*it);
+    }
+  }
+  else
+  {
+    // get all attributes
+    for (int i = 0; i < mProvider->mAttributeFields.count(); i++)
+    {
+      if ( fieldCount != 0 )
+        mStatement += ",";
+      mStatement += "[" + mProvider->mAttributeFields[i].name() + "]";
+
+      if ( !mProvider->mFidColName.isEmpty() && mProvider->mFidColName == mProvider->mAttributeFields[i].name() )
+          mFidCol = fieldCount;
+
+      ++fieldCount;
+      mAttributesToFetch.append(i);
+    }
+  }
+  // get fid col if not yet required
+  if ( mFidCol == -1 && !mProvider->mFidColName.isEmpty() )
+  {
+    if ( fieldCount != 0 )
+      mStatement += ",";
+    mStatement += "[" + mProvider->mFidColName + "]";
+    mFidCol = fieldCount;
+    ++fieldCount;
+  }
+  // get geometry col
+  if ( request.flags() != QgsFeatureRequest::NoGeometry && !mProvider->mGeometryColName.isEmpty() )
+  {
+    if ( fieldCount != 0 )
+      mStatement += ",";
+    mStatement += "[" + mProvider->mGeometryColName + "]";
+    mGeometryCol = fieldCount;
+    ++fieldCount;
+  }
+
+  mStatement += " from ";
+  if ( !mProvider->mSchemaName.isEmpty() )
+    mStatement += "[" + mProvider->mSchemaName + "].";
+
+  mStatement += "[" + mProvider->mTableName + "]";
+
+  bool filterAdded = false;
+  // set spatial filter
+  if ( request.filterType() & QgsFeatureRequest::FilterRect)
+  {
+    // polygons should be CCW for SqlGeography
+    QString r;
+    QTextStream foo( &r );
+
+    foo.setRealNumberPrecision( 8 );
+    foo.setRealNumberNotation( QTextStream::FixedNotation );
+    foo <<  request.filterRect().xMinimum() << " " <<  request.filterRect().yMinimum() << ", "
+    <<  request.filterRect().xMaximum() << " " <<  request.filterRect().yMinimum() << ", "
+    <<  request.filterRect().xMaximum() << " " <<  request.filterRect().yMaximum() << ", "
+    <<  request.filterRect().xMinimum() << " " <<  request.filterRect().yMaximum() << ", "
+    <<  request.filterRect().xMinimum() << " " <<  request.filterRect().yMinimum();
+
+    mStatement += QString( " where [%1].STIntersects([%2]::STGeomFromText('POLYGON((%3))',%4)) = 1" ).arg(
+                    mProvider->mGeometryColName, mProvider->mGeometryColType, r, QString::number( mProvider->mSRId ) );
+    filterAdded = true;
+  }
+
+  // set fid filter
+  if ( (request.filterType() & QgsFeatureRequest::FilterFid) && !mProvider->mFidColName.isEmpty() )
+  {
+    // set attribute filter
+    if ( !filterAdded )
+      mStatement += QString( " where [%1] = %2" ).arg( mProvider->mFidColName, QString::number( request.filterFid() ) );
+    else
+      mStatement +=QString( " and [%1] = %2" ).arg( mProvider->mFidColName, QString::number( request.filterFid() ) );
+    filterAdded = true;
+  }
+
+  if ( !mProvider->mSqlWhereClause.isEmpty() )
+  {
+    if ( !filterAdded )
+      mStatement += " where (" + mProvider->mSqlWhereClause + ")";
+    else
+      mStatement += " and (" + mProvider->mSqlWhereClause + ")";
+    filterAdded = true;
+  }
+
+  if ( fieldCount == 0 )
+  {
+    QgsDebugMsg( "QgsMssqlProvider::select no fields have been requested" );
+    mStatement.clear();
+  }
+}
+
+
+bool QgsMssqlFeatureIterator::nextFeature( QgsFeature& feature )
+{
+  feature.setValid( false );
+
+  if (!mQuery)
+    return false;
+
+  if ( !mQuery->isActive() )
+  {
+    QgsDebugMsg( "Read attempt on inactive query" );
+    return false;
+  }
+
+  if ( mQuery->next() )
+  {
+    feature.initAttributes( mProvider->mAttributeFields.count() );
+    feature.setFields( &mProvider->mAttributeFields ); // allow name-based attribute lookups
+
+    for (int i = 0; i < mAttributesToFetch.count(); i++)
+    {
+      QVariant v = mQuery->value( i );
+      feature.setAttribute( mAttributesToFetch[i], mQuery->value( i ) );
+    }
+
+    if ( mFidCol >= 0 )
+    {
+      feature.setFeatureId( mQuery->value( mFidCol ).toLongLong() );
+    }
+
+    if ( mGeometryCol >= 0 )
+    {
+      QByteArray ar = mQuery->value( mGeometryCol ).toByteArray();
+      unsigned char* wkb = mProvider->parser.ParseSqlGeometry(( unsigned char* )ar.data(), ar.size() );
+      if ( wkb )
+      {
+        feature.setGeometryAndOwnership( wkb, mProvider->parser.GetWkbLen() );
+      }
+    }
+
+    feature.setValid( true );
+    return true;
+  }
+  return false;
+}
+
+
+bool QgsMssqlFeatureIterator::rewind()
+{
+  if ( mStatement.isEmpty() )
+  {
+    QgsDebugMsg( "QgsMssqlFeatureIterator::rewind on empty statement" );
+    return false;
+  }
+
+  if (!mQuery)
+    return false;
+
+  mQuery->clear();
+  mQuery->setForwardOnly( true );
+  if ( !mQuery->exec( mStatement ) )
+  {
+    QString msg = mQuery->lastError().text();
+    QgsDebugMsg( msg );
+  }
+  else
+      mIsOpen = true;
+
+  return true;
+}
+
+bool QgsMssqlFeatureIterator::close()
+{
+  mIsOpen = false;
+  if (!mQuery)
+    return false;
+
+  if ( !mQuery->isActive() )
+  {
+    QgsDebugMsg( "QgsMssqlFeatureIterator::close on inactive query" );
+    return false;
+  }
+
+  mQuery->finish();
+  return true;
+}
+
+///////////////
+

src/providers/mssql/qgsmssqlfeatureiterator.h

@@ -0,0 +1,76 @@
+/***************************************************************************
+                         qgsmssqlfeatureiterator.h  -  description
+                         -------------------
+    begin                : 2011-10-08
+    copyright            : (C) 2011 by Tamas Szekeres
+    email                : szekerest at gmail.com
+ ***************************************************************************/
+
+/***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSMSSQLFEATUREITERATOR_H
+#define QGSMSSQLFEATUREITERATOR_H
+
+#include "qgsmssqlprovider.h"
+#include "qgsfeatureiterator.h"
+#include <QtSql/QSqlDatabase>
+#include <QtSql/QSqlQuery>
+#include <QtSql/QSqlError>
+
+class QgsMssqlProvider;
+
+class QgsMssqlFeatureIterator : public QgsAbstractFeatureIterator
+{
+  public:
+    QgsMssqlFeatureIterator( QgsMssqlProvider* provider, const QgsFeatureRequest& request);
+
+    ~QgsMssqlFeatureIterator();
+
+    //! fetch next feature, return true on success
+    virtual bool nextFeature( QgsFeature& feature );
+
+    //! reset the iterator to the starting position
+    virtual bool rewind();
+
+    //! end of iterating: free the resources / lock
+    virtual bool close();
+
+  protected:
+    QgsMssqlProvider* mProvider;
+
+    void BuildStatement( const QgsFeatureRequest& request );
+
+  private:
+    // The current database
+    QSqlDatabase mDatabase;
+
+    // The current sql query
+    QSqlQuery* mQuery;
+
+    // Use query on provider (no new connection added)
+    bool mUseProviderQuery;
+
+    // The current sql statement
+    QString mStatement;
+
+    // Open connection flag
+    bool mIsOpen;
+
+    // Field index of FID column
+    long mFidCol;
+
+    // Field index of geometry column
+    long mGeometryCol; 
+
+    // List of attribute indices to fetch with nextFeature calls
+    QgsAttributeList mAttributesToFetch;
+};
+
+#endif // QGSMSSQLFEATUREITERATOR_H