[WFS provider] Improve tooltip of SQL statement field when joins are possible, and a warning when specifying a geometry field of another layer in the selected columns

Author: rouault

src/gui/qgssqlcomposerdialog.cpp

@@ -158,14 +158,18 @@ void QgsSQLComposerDialog::accept()
 {
   if ( mSQLValidatorCallback )
   {
-    QString errorMsg;
-    if ( !mSQLValidatorCallback->isValid( sql(), errorMsg ) )
+    QString errorMsg, warningMsg;
+    if ( !mSQLValidatorCallback->isValid( sql(), errorMsg, warningMsg ) )
     {
       if ( errorMsg.isEmpty() )
         errorMsg = tr( "An error occurred during evaluation of the SQL statement" );
       QMessageBox::critical( this, tr( "SQL error" ), errorMsg );
       return;
     }
+    if ( !warningMsg.isEmpty() )
+    {
+      QMessageBox::warning( this, tr( "SQL warning" ), warningMsg );
+    }
   }
   QDialog::accept();
 }
@@ -710,11 +714,18 @@ void QgsSQLComposerDialog::addApis( const QStringList& list )
   mQueryEdit->lexer()->setAPIs( apis );
 }
 
-void QgsSQLComposerDialog::setSupportMultipleTables( bool on )
+void QgsSQLComposerDialog::setSupportMultipleTables( bool on, QString mainTypename )
 {
   mJoinsLabels->setVisible( on );
   mTableJoins->setVisible( on );
   mAddJoinButton->setVisible( on );
   mRemoveJoinButton->setVisible( on );
   mTablesCombo->setVisible( on );
+
+  QString mainTypenameFormatted;
+  if ( !mainTypename.isEmpty() )
+    mainTypenameFormatted = " (" + mainTypename + ")";
+  mQueryEdit->setToolTip( tr( "This is the SQL query editor. The SQL statement can select data from several tables, \n"
+                              "but it must compulsory include the main typename%1 in the selected tables, \n"
+                              "and only the geometry column of the main typename can be used as the geometry column of the resulting layer." ).arg( mainTypenameFormatted ) );
 }

src/gui/qgssqlcomposerdialog.h

@@ -62,7 +62,7 @@ class GUI_EXPORT QgsSQLComposerDialog : public QDialog, private Ui::QgsSQLCompos
       public:
         virtual ~SQLValidatorCallback();
         //! method should return true if the SQL is valid. Otherwise return false and set the errorReason
-        virtual bool isValid( const QString& sql, QString& errorReason ) = 0;
+        virtual bool isValid( const QString& sql, QString& errorReason, QString& warningMsg ) = 0;
     };
 
     //! argument of a function
@@ -131,7 +131,7 @@ class GUI_EXPORT QgsSQLComposerDialog : public QDialog, private Ui::QgsSQLCompos
     void addApis( const QStringList& list );
 
     //! set if multiple tables/joins are supported. Default is false
-    void setSupportMultipleTables( bool );
+    void setSupportMultipleTables( bool bMultipleTables, QString mainTypename = QString() );
 
     /** Set a callback that will be called when a new table is selected, so
         that new column names can be added typically.

src/providers/wfs/qgswfsprovider.cpp

@@ -86,7 +86,7 @@ QgsWFSProvider::QgsWFSProvider( const QString& uri, const QgsWFSCapabilities::Ca
 
   if ( !mShared->mURI.sql().isEmpty() )
   {
-    if ( !processSQL( mShared->mURI.sql(), mProcessSQLErrorMsg ) )
+    if ( !processSQL( mShared->mURI.sql(), mProcessSQLErrorMsg, mProcessSQLWarningMsg ) )
     {
       QgsMessageLog::logMessage( mProcessSQLErrorMsg, tr( "WFS" ) );
       mValid = false;
@@ -270,10 +270,11 @@ void QgsWFSProviderSQLColumnRefValidator::visit( const QgsSQLStatement::NodeColu
 }
 
 
-bool QgsWFSProvider::processSQL( const QString& sqlString, QString& errorMsg )
+bool QgsWFSProvider::processSQL( const QString& sqlString, QString& errorMsg, QString& warningMsg )
 {
   QgsDebugMsg( QString( "Processing SQL: %1" ).arg( sqlString ) );
   errorMsg.clear();
+  warningMsg.clear();
   QgsSQLStatement sql( sqlString );
   if ( sql.hasParserError() )
   {
@@ -557,8 +558,17 @@ bool QgsWFSProvider::processSQL( const QString& sqlString, QString& errorMsg )
         }
       }
     }
+    // Geometry field
+    else if ( mapTypenameToGeometryAttribute[columnTableTypename] == columnRef->name() )
+    {
+      if ( columnTableTypename != mShared->mURI.typeName() )
+      {
+        warningMsg = tr( "The geometry field of a typename that is not the main typename is ignored in the selected fields" );
+        QgsDebugMsg( warningMsg );
+      }
+    }
     // Regular field
-    else if ( mapTypenameToGeometryAttribute[columnTableTypename] != columnRef->name() )
+    else
     {
       const QgsFields tableFields = mapTypenameToFields[columnTableTypename];
       int idx = tableFields.fieldNameIndex( columnRef->name() );
@@ -633,8 +643,8 @@ bool QgsWFSProvider::setSubsetString( const QString& theSQL, bool updateFeatureC
   mShared->mDistinctSelect = false;
   if ( theSQL.startsWith( "SELECT ", Qt::CaseInsensitive ) )
   {
-    QString errorMsg;
-    if ( !processSQL( theSQL, errorMsg ) )
+    QString errorMsg, warningMsg;
+    if ( !processSQL( theSQL, errorMsg, warningMsg ) )
     {
       QgsMessageLog::logMessage( errorMsg, tr( "WFS" ) );
       return false;

src/providers/wfs/qgswfsprovider.h

@@ -101,6 +101,8 @@ class QgsWFSProvider : public QgsVectorDataProvider
 
     const QString processSQLErrorMsg() const { return mProcessSQLErrorMsg; }
 
+    const QString processSQLWarningMsg() const { return mProcessSQLWarningMsg; }
+
     //Editing operations
     /**
      * Adds a list of features
@@ -165,6 +167,7 @@ class QgsWFSProvider : public QgsVectorDataProvider
     QgsFields mThisTypenameFields;
 
     QString mProcessSQLErrorMsg;
+    QString mProcessSQLWarningMsg;
 
     /** Collects information about the field types. Is called internally from QgsWFSProvider ctor.
        The method gives back the name of
@@ -202,7 +205,7 @@ class QgsWFSProvider : public QgsVectorDataProvider
     /** Convert the value to its appropriate XML representation */
     QString convertToXML( const QVariant& value );
 
-    bool processSQL( const QString& sqlString, QString& errorMsg );
+    bool processSQL( const QString& sqlString, QString& errorMsg, QString& warningMsg );
 };
 
 #endif /* QGSWFSPROVIDER_H */

src/providers/wfs/qgswfssourceselect.cpp

@@ -409,7 +409,7 @@ class QgsWFSValidatorCallback: public QObject, public QgsSQLComposerDialog::SQLV
     QgsWFSValidatorCallback( QObject* parent,
                              const QgsWFSDataSourceURI& uri, const QString& allSql,
                              const QgsWFSCapabilities::Capabilities& caps );
-    bool isValid( const QString& sql, QString& errorReason ) override;
+    bool isValid( const QString& sql, QString& errorReason, QString& warningMsg ) override;
   private:
     QgsWFSDataSourceURI mURI;
     QString mAllSql;
@@ -427,7 +427,7 @@ QgsWFSValidatorCallback::QgsWFSValidatorCallback( QObject* parent,
 {
 }
 
-bool QgsWFSValidatorCallback::isValid( const QString& sqlStr, QString& errorReason )
+bool QgsWFSValidatorCallback::isValid( const QString& sqlStr, QString& errorReason, QString& warningMsg )
 {
   errorReason.clear();
   if ( sqlStr.isEmpty() || sqlStr == mAllSql )
@@ -441,6 +441,7 @@ bool QgsWFSValidatorCallback::isValid( const QString& sqlStr, QString& errorReas
     errorReason = p.processSQLErrorMsg();
     return false;
   }
+  warningMsg = p.processSQLWarningMsg();
 
   return true;
 }
@@ -546,7 +547,7 @@ void QgsWFSSourceSelect::buildQuery( const QModelIndex& index )
   d->setTableSelectedCallback( tableSelectedCbk );
 
   const bool bSupportJoins = mCaps.featureTypes.size() > 1 && mCaps.supportsJoins;
-  d->setSupportMultipleTables( bSupportJoins );
+  d->setSupportMultipleTables( bSupportJoins, QgsSQLStatement::quotedIdentifierIfNeeded( displayedTypeName ) );
 
   QMap< QString, QString > mapTypenameToTitle;
   Q_FOREACH ( const QgsWFSCapabilities::FeatureType f, mCaps.featureTypes )