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qgsspatialitefeatureiterator.cpp
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qgsspatialitefeatureiterator.cpp
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/***************************************************************************
qgsspatialitefeatureiterator.cpp
---------------------
begin : Juli 2012
copyright : (C) 2012 by Martin Dobias
email : wonder dot sk at gmail dot 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 "qgsspatialitefeatureiterator.h"
#include "qgsspatialiteconnection.h"
#include "qgsspatialiteconnpool.h"
#include "qgsspatialiteprovider.h"
#include "qgssqliteexpressioncompiler.h"
#include "qgsgeometry.h"
#include "qgslogger.h"
#include "qgsmessagelog.h"
#include "qgsjsonutils.h"
#include "qgssettings.h"
#include "qgsexception.h"
QgsSpatiaLiteFeatureIterator::QgsSpatiaLiteFeatureIterator( QgsSpatiaLiteFeatureSource *source, bool ownSource, const QgsFeatureRequest &request )
: QgsAbstractFeatureIteratorFromSource<QgsSpatiaLiteFeatureSource>( source, ownSource, request )
{
mHandle = QgsSpatiaLiteConnPool::instance()->acquireConnection( mSource->mSqlitePath, request.timeout(), request.requestMayBeNested() );
mFetchGeometry = !mSource->mGeometryColumn.isNull() && !( mRequest.flags() & QgsFeatureRequest::NoGeometry );
mHasPrimaryKey = !mSource->mPrimaryKey.isEmpty();
mRowNumber = 0;
QStringList whereClauses;
bool useFallbackWhereClause = false;
QString fallbackWhereClause;
QString whereClause;
if ( mRequest.destinationCrs().isValid() && mRequest.destinationCrs() != mSource->mCrs )
{
mTransform = QgsCoordinateTransform( mSource->mCrs, mRequest.destinationCrs(), mRequest.transformContext() );
}
try
{
mFilterRect = filterRectToSourceCrs( mTransform );
}
catch ( QgsCsException & )
{
// can't reproject mFilterRect
close();
return;
}
//beware - limitAtProvider needs to be set to false if the request cannot be completely handled
//by the provider (e.g., utilising QGIS expression filters)
bool limitAtProvider = ( mRequest.limit() >= 0 );
if ( !mFilterRect.isNull() && !mSource->mGeometryColumn.isNull() )
{
// some kind of MBR spatial filtering is required
whereClause = whereClauseRect();
if ( ! whereClause.isEmpty() )
{
whereClauses.append( whereClause );
}
}
if ( !mSource->mSubsetString.isEmpty() )
{
whereClause = "( " + mSource->mSubsetString + ')';
if ( ! whereClause.isEmpty() )
{
whereClauses.append( whereClause );
}
}
if ( request.filterType() == QgsFeatureRequest::FilterFid )
{
whereClause = whereClauseFid();
if ( ! whereClause.isEmpty() )
{
whereClauses.append( whereClause );
}
}
else if ( request.filterType() == QgsFeatureRequest::FilterFids )
{
if ( request.filterFids().isEmpty() )
{
close();
}
else
{
whereClauses.append( whereClauseFids() );
}
}
//IMPORTANT - this MUST be the last clause added!
else if ( request.filterType() == QgsFeatureRequest::FilterExpression )
{
// ensure that all attributes required for expression filter are being fetched
if ( mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes && request.filterType() == QgsFeatureRequest::FilterExpression )
{
QgsAttributeList attrs = request.subsetOfAttributes();
//ensure that all fields required for filter expressions are prepared
QSet<int> attributeIndexes = request.filterExpression()->referencedAttributeIndexes( mSource->mFields );
attributeIndexes += attrs.toSet();
mRequest.setSubsetOfAttributes( attributeIndexes.toList() );
}
if ( request.filterExpression()->needsGeometry() )
{
mFetchGeometry = true;
}
if ( QgsSettings().value( QStringLiteral( "qgis/compileExpressions" ), true ).toBool() )
{
QgsSQLiteExpressionCompiler compiler = QgsSQLiteExpressionCompiler( source->mFields );
QgsSqlExpressionCompiler::Result result = compiler.compile( request.filterExpression() );
if ( result == QgsSqlExpressionCompiler::Complete || result == QgsSqlExpressionCompiler::Partial )
{
whereClause = compiler.result();
if ( !whereClause.isEmpty() )
{
useFallbackWhereClause = true;
fallbackWhereClause = whereClauses.join( QStringLiteral( " AND " ) );
whereClauses.append( whereClause );
//if only partial success when compiling expression, we need to double-check results using QGIS' expressions
mExpressionCompiled = ( result == QgsSqlExpressionCompiler::Complete );
mCompileStatus = ( mExpressionCompiled ? Compiled : PartiallyCompiled );
}
}
if ( result != QgsSqlExpressionCompiler::Complete )
{
//can't apply limit at provider side as we need to check all results using QGIS expressions
limitAtProvider = false;
}
}
else
{
limitAtProvider = false;
}
}
if ( !mClosed )
{
whereClause = whereClauses.join( QStringLiteral( " AND " ) );
// Setup the order by
QStringList orderByParts;
mOrderByCompiled = true;
if ( QgsSettings().value( QStringLiteral( "qgis/compileExpressions" ), true ).toBool() )
{
Q_FOREACH ( const QgsFeatureRequest::OrderByClause &clause, request.orderBy() )
{
QgsSQLiteExpressionCompiler compiler = QgsSQLiteExpressionCompiler( source->mFields );
QgsExpression expression = clause.expression();
if ( compiler.compile( &expression ) == QgsSqlExpressionCompiler::Complete )
{
QString part;
part = compiler.result();
if ( clause.nullsFirst() )
orderByParts << QStringLiteral( "%1 IS NOT NULL" ).arg( part );
else
orderByParts << QStringLiteral( "%1 IS NULL" ).arg( part );
part += clause.ascending() ? " COLLATE NOCASE ASC" : " COLLATE NOCASE DESC";
orderByParts << part;
}
else
{
// Bail out on first non-complete compilation.
// Most important clauses at the beginning of the list
// will still be sent and used to pre-sort so the local
// CPU can use its cycles for fine-tuning.
mOrderByCompiled = false;
break;
}
}
}
else
{
mOrderByCompiled = false;
}
if ( !mOrderByCompiled )
limitAtProvider = false;
// also need attributes required by order by
if ( !mOrderByCompiled && mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes && !mRequest.orderBy().isEmpty() )
{
QSet<int> attributeIndexes;
Q_FOREACH ( const QString &attr, mRequest.orderBy().usedAttributes() )
{
attributeIndexes << mSource->mFields.lookupField( attr );
}
attributeIndexes += mRequest.subsetOfAttributes().toSet();
mRequest.setSubsetOfAttributes( attributeIndexes.toList() );
}
// preparing the SQL statement
bool success = prepareStatement( whereClause, limitAtProvider ? mRequest.limit() : -1, orderByParts.join( QStringLiteral( "," ) ) );
if ( !success && useFallbackWhereClause )
{
//try with the fallback where clause, e.g., for cases when using compiled expression failed to prepare
mExpressionCompiled = false;
success = prepareStatement( fallbackWhereClause, -1, orderByParts.join( QStringLiteral( "," ) ) );
mCompileFailed = true;
}
if ( !success )
{
// some error occurred
sqliteStatement = nullptr;
close();
}
}
}
QgsSpatiaLiteFeatureIterator::~QgsSpatiaLiteFeatureIterator()
{
close();
}
bool QgsSpatiaLiteFeatureIterator::fetchFeature( QgsFeature &feature )
{
feature.setValid( false );
if ( mClosed )
return false;
if ( !sqliteStatement )
{
QgsDebugMsg( "Invalid current SQLite statement" );
close();
return false;
}
if ( !getFeature( sqliteStatement, feature ) )
{
sqlite3_finalize( sqliteStatement );
sqliteStatement = nullptr;
close();
return false;
}
feature.setValid( true );
geometryToDestinationCrs( feature, mTransform );
return true;
}
bool QgsSpatiaLiteFeatureIterator::nextFeatureFilterExpression( QgsFeature &f )
{
if ( !mExpressionCompiled )
return QgsAbstractFeatureIterator::nextFeatureFilterExpression( f );
else
return fetchFeature( f );
}
bool QgsSpatiaLiteFeatureIterator::rewind()
{
if ( mClosed )
return false;
if ( sqlite3_reset( sqliteStatement ) == SQLITE_OK )
{
mRowNumber = 0;
return true;
}
else
{
return false;
}
}
bool QgsSpatiaLiteFeatureIterator::close()
{
if ( mClosed )
return false;
iteratorClosed();
if ( !mHandle )
{
mClosed = true;
return false;
}
if ( sqliteStatement )
{
sqlite3_finalize( sqliteStatement );
sqliteStatement = nullptr;
}
QgsSpatiaLiteConnPool::instance()->releaseConnection( mHandle );
mHandle = nullptr;
mClosed = true;
return true;
}
////
bool QgsSpatiaLiteFeatureIterator::prepareStatement( const QString &whereClause, long limit, const QString &orderBy )
{
if ( !mHandle )
return false;
try
{
QString sql = QStringLiteral( "SELECT %1" ).arg( mHasPrimaryKey ? quotedPrimaryKey() : QStringLiteral( "0" ) );
int colIdx = 1; // column 0 is primary key
if ( mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes )
{
QgsAttributeList fetchAttributes = mRequest.subsetOfAttributes();
for ( QgsAttributeList::const_iterator it = fetchAttributes.constBegin(); it != fetchAttributes.constEnd(); ++it )
{
sql += ',' + fieldName( mSource->mFields.field( *it ) );
colIdx++;
}
}
else
{
// fetch all attributes
for ( int idx = 0; idx < mSource->mFields.count(); ++idx )
{
sql += ',' + fieldName( mSource->mFields.at( idx ) );
colIdx++;
}
}
if ( mFetchGeometry )
{
sql += QStringLiteral( ", AsBinary(%1)" ).arg( QgsSpatiaLiteProvider::quotedIdentifier( mSource->mGeometryColumn ) );
mGeomColIdx = colIdx;
}
sql += QStringLiteral( " FROM %1" ).arg( mSource->mQuery );
if ( !whereClause.isEmpty() )
sql += QStringLiteral( " WHERE %1" ).arg( whereClause );
if ( !orderBy.isEmpty() )
sql += QStringLiteral( " ORDER BY %1" ).arg( orderBy );
if ( limit >= 0 )
sql += QStringLiteral( " LIMIT %1" ).arg( limit );
if ( sqlite3_prepare_v2( mHandle->handle(), sql.toUtf8().constData(), -1, &sqliteStatement, nullptr ) != SQLITE_OK )
{
// some error occurred
QgsMessageLog::logMessage( QObject::tr( "SQLite error: %2\nSQL: %1" ).arg( sql, sqlite3_errmsg( mHandle->handle() ) ), QObject::tr( "SpatiaLite" ) );
return false;
}
}
catch ( QgsSpatiaLiteProvider::SLFieldNotFound )
{
rewind();
return false;
}
return true;
}
QString QgsSpatiaLiteFeatureIterator::quotedPrimaryKey()
{
return mSource->mPrimaryKey.isEmpty() ? QStringLiteral( "ROWID" ) : QgsSpatiaLiteProvider::quotedIdentifier( mSource->mPrimaryKey );
}
QString QgsSpatiaLiteFeatureIterator::whereClauseFid()
{
return QStringLiteral( "%1=%2" ).arg( quotedPrimaryKey() ).arg( mRequest.filterFid() );
}
QString QgsSpatiaLiteFeatureIterator::whereClauseFids()
{
if ( mRequest.filterFids().isEmpty() )
return QLatin1String( "" );
QString expr = QStringLiteral( "%1 IN (" ).arg( quotedPrimaryKey() ), delim;
Q_FOREACH ( const QgsFeatureId featureId, mRequest.filterFids() )
{
expr += delim + QString::number( featureId );
delim = ',';
}
expr += ')';
return expr;
}
QString QgsSpatiaLiteFeatureIterator::whereClauseRect()
{
QString whereClause;
if ( mRequest.flags() & QgsFeatureRequest::ExactIntersect )
{
// we are requested to evaluate a true INTERSECT relationship
whereClause += QStringLiteral( "Intersects(%1, BuildMbr(%2)) AND " ).arg( QgsSpatiaLiteProvider::quotedIdentifier( mSource->mGeometryColumn ), mbr( mFilterRect ) );
}
if ( mSource->mVShapeBased )
{
// handling a VirtualShape layer
whereClause += QStringLiteral( "MbrIntersects(%1, BuildMbr(%2))" ).arg( QgsSpatiaLiteProvider::quotedIdentifier( mSource->mGeometryColumn ), mbr( mFilterRect ) );
}
else if ( mFilterRect.isFinite() )
{
if ( mSource->mSpatialIndexRTree )
{
// using the RTree spatial index
QString mbrFilter = QStringLiteral( "xmin <= %1 AND " ).arg( qgsDoubleToString( mFilterRect.xMaximum() ) );
mbrFilter += QStringLiteral( "xmax >= %1 AND " ).arg( qgsDoubleToString( mFilterRect.xMinimum() ) );
mbrFilter += QStringLiteral( "ymin <= %1 AND " ).arg( qgsDoubleToString( mFilterRect.yMaximum() ) );
mbrFilter += QStringLiteral( "ymax >= %1" ).arg( qgsDoubleToString( mFilterRect.yMinimum() ) );
QString idxName = QStringLiteral( "idx_%1_%2" ).arg( mSource->mIndexTable, mSource->mIndexGeometry );
whereClause += QStringLiteral( "%1 IN (SELECT pkid FROM %2 WHERE %3)" )
.arg( quotedPrimaryKey(),
QgsSpatiaLiteProvider::quotedIdentifier( idxName ),
mbrFilter );
}
else if ( mSource->mSpatialIndexMbrCache )
{
// using the MbrCache spatial index
QString idxName = QStringLiteral( "cache_%1_%2" ).arg( mSource->mIndexTable, mSource->mIndexGeometry );
whereClause += QStringLiteral( "%1 IN (SELECT rowid FROM %2 WHERE mbr = FilterMbrIntersects(%3))" )
.arg( quotedPrimaryKey(),
QgsSpatiaLiteProvider::quotedIdentifier( idxName ),
mbr( mFilterRect ) );
}
else
{
// using simple MBR filtering
whereClause += QStringLiteral( "MbrIntersects(%1, BuildMbr(%2))" ).arg( QgsSpatiaLiteProvider::quotedIdentifier( mSource->mGeometryColumn ), mbr( mFilterRect ) );
}
}
else
{
whereClause = '1';
}
return whereClause;
}
QString QgsSpatiaLiteFeatureIterator::mbr( const QgsRectangle &rect )
{
return QStringLiteral( "%1, %2, %3, %4" )
.arg( qgsDoubleToString( rect.xMinimum() ),
qgsDoubleToString( rect.yMinimum() ),
qgsDoubleToString( rect.xMaximum() ),
qgsDoubleToString( rect.yMaximum() ) );
}
QString QgsSpatiaLiteFeatureIterator::fieldName( const QgsField &fld )
{
QString fieldname = QgsSpatiaLiteProvider::quotedIdentifier( fld.name() );
const QString type = fld.typeName().toLower();
if ( type.contains( QLatin1String( "geometry" ) ) || type.contains( QLatin1String( "point" ) ) ||
type.contains( QLatin1String( "line" ) ) || type.contains( QLatin1String( "polygon" ) ) )
{
fieldname = QStringLiteral( "AsText(%1)" ).arg( fieldname );
}
return fieldname;
}
bool QgsSpatiaLiteFeatureIterator::getFeature( sqlite3_stmt *stmt, QgsFeature &feature )
{
bool subsetAttributes = mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes;
int ret = sqlite3_step( stmt );
if ( ret == SQLITE_DONE )
{
// there are no more rows to fetch
return false;
}
if ( ret != SQLITE_ROW )
{
// some unexpected error occurred
QgsMessageLog::logMessage( QObject::tr( "SQLite error getting feature: %1" ).arg( QString::fromUtf8( sqlite3_errmsg( mHandle->handle() ) ) ), QObject::tr( "SpatiaLite" ) );
return false;
}
// one valid row has been fetched from the result set
if ( !mFetchGeometry )
{
// no geometry was required
feature.clearGeometry();
}
feature.initAttributes( mSource->mFields.count() );
feature.setFields( mSource->mFields ); // allow name-based attribute lookups
int ic;
int n_columns = sqlite3_column_count( stmt );
for ( ic = 0; ic < n_columns; ic++ )
{
if ( ic == 0 )
{
if ( mHasPrimaryKey )
{
// first column always contains the ROWID (or the primary key)
QgsFeatureId fid = sqlite3_column_int64( stmt, ic );
QgsDebugMsgLevel( QString( "fid=%1" ).arg( fid ), 3 );
feature.setId( fid );
}
else
{
// autoincrement a row number
mRowNumber++;
feature.setId( mRowNumber );
}
}
else if ( mFetchGeometry && ic == mGeomColIdx )
{
getFeatureGeometry( stmt, ic, feature );
}
else
{
if ( subsetAttributes )
{
if ( ic <= mRequest.subsetOfAttributes().size() )
{
const int attrIndex = mRequest.subsetOfAttributes().at( ic - 1 );
const QgsField field = mSource->mFields.at( attrIndex );
feature.setAttribute( attrIndex, getFeatureAttribute( stmt, ic, field.type(), field.subType() ) );
}
}
else
{
const int attrIndex = ic - 1;
const QgsField field = mSource->mFields.at( attrIndex );
feature.setAttribute( attrIndex, getFeatureAttribute( stmt, ic, field.type(), field.subType() ) );
}
}
}
return true;
}
QVariant QgsSpatiaLiteFeatureIterator::getFeatureAttribute( sqlite3_stmt *stmt, int ic, QVariant::Type type, QVariant::Type subType )
{
if ( sqlite3_column_type( stmt, ic ) == SQLITE_INTEGER )
{
if ( type == QVariant::Int )
{
// INTEGER value
return sqlite3_column_int( stmt, ic );
}
else
{
// INTEGER value
return ( qint64 ) sqlite3_column_int64( stmt, ic );
}
}
if ( sqlite3_column_type( stmt, ic ) == SQLITE_FLOAT )
{
// DOUBLE value
return sqlite3_column_double( stmt, ic );
}
if ( sqlite3_column_type( stmt, ic ) == SQLITE_TEXT )
{
// TEXT value
const QString txt = QString::fromUtf8( ( const char * ) sqlite3_column_text( stmt, ic ) );
if ( type == QVariant::List || type == QVariant::StringList )
{
// assume arrays are stored as JSON
QVariant result = QVariant( QgsJsonUtils::parseArray( txt, subType ) );
result.convert( type );
return result;
}
return txt;
}
// assuming NULL
return QVariant( type );
}
void QgsSpatiaLiteFeatureIterator::getFeatureGeometry( sqlite3_stmt *stmt, int ic, QgsFeature &feature )
{
if ( sqlite3_column_type( stmt, ic ) == SQLITE_BLOB )
{
unsigned char *featureGeom = nullptr;
int geom_size = 0;
const void *blob = sqlite3_column_blob( stmt, ic );
int blob_size = sqlite3_column_bytes( stmt, ic );
QgsSpatiaLiteProvider::convertToGeosWKB( ( const unsigned char * )blob, blob_size, &featureGeom, &geom_size );
if ( featureGeom )
{
QgsGeometry g;
g.fromWkb( featureGeom, geom_size );
feature.setGeometry( g );
}
else
feature.clearGeometry();
}
else
{
// NULL geometry
feature.clearGeometry();
}
}
bool QgsSpatiaLiteFeatureIterator::prepareOrderBy( const QList<QgsFeatureRequest::OrderByClause> &orderBys )
{
Q_UNUSED( orderBys )
// Preparation has already been done in the constructor, so we just communicate the result
return mOrderByCompiled;
}
QgsSpatiaLiteFeatureSource::QgsSpatiaLiteFeatureSource( const QgsSpatiaLiteProvider *p )
: mGeometryColumn( p->mGeometryColumn )
, mSubsetString( p->mSubsetString )
, mFields( p->mAttributeFields )
, mQuery( p->mQuery )
, mIsQuery( p->mIsQuery )
, mViewBased( p->mViewBased )
, mVShapeBased( p->mVShapeBased )
, mIndexTable( p->mIndexTable )
, mIndexGeometry( p->mIndexGeometry )
, mPrimaryKey( p->mPrimaryKey )
, mSpatialIndexRTree( p->mSpatialIndexRTree )
, mSpatialIndexMbrCache( p->mSpatialIndexMbrCache )
, mSqlitePath( p->mSqlitePath )
, mCrs( p->crs() )
{
}
QgsFeatureIterator QgsSpatiaLiteFeatureSource::getFeatures( const QgsFeatureRequest &request )
{
return QgsFeatureIterator( new QgsSpatiaLiteFeatureIterator( this, false, request ) );
}