Add field name in layers from postgis relation with multiple spatial fields

NOTE: only works with browser, not with "Add PostGIS Layer" dialog

Author: Sandro Santilli

src/providers/postgres/qgspostgresconn.cpp

@@ -270,30 +270,39 @@ void QgsPostgresConn::disconnect()
   deleteLater();
 }
 
-QStringList QgsPostgresConn::pkCandidates( QString schemaName, QString viewName )
+/* private */
+void QgsPostgresConn::addColumnInfo( QgsPostgresLayerProperty& layerProperty, const QString& schemaName, const QString& viewName, bool fetchPkCandidates )
 {
-  QStringList cols;
-
-  QString sql = QString( "SELECT attname FROM pg_attribute JOIN pg_type ON atttypid=pg_type.oid WHERE attrelid=regclass('%1.%2')" )
-                .arg( quotedIdentifier( schemaName ) )
-                .arg( quotedIdentifier( viewName ) );
+  // TODO: optimize this query when pk candidates aren't needed
+  //       could use array_agg() and count()
+  //       array output would look like this: "{One,tWo}"
+  QString sql = QString( "SELECT attname, CASE WHEN typname = ANY(ARRAY['geometry','geography','topogeometry']) THEN 1 ELSE null END AS isSpatial FROM pg_attribute JOIN pg_type ON atttypid=pg_type.oid WHERE attrelid=regclass('%1.%2')" )
+              .arg( quotedIdentifier( schemaName ) )
+              .arg( quotedIdentifier( viewName ) );
   QgsDebugMsg( sql );
   QgsPostgresResult colRes = PQexec( sql );
 
+  layerProperty.nSpCols = 0;
+
   if ( colRes.PQresultStatus() == PGRES_TUPLES_OK )
   {
     for ( int i = 0; i < colRes.PQntuples(); i++ )
     {
-      QgsDebugMsg( colRes.PQgetvalue( i, 0 ) );
-      cols << colRes.PQgetvalue( i, 0 );
+      if ( fetchPkCandidates ) {
+        QgsDebugMsg( colRes.PQgetvalue( i, 0 ) );
+        layerProperty.pkCols << colRes.PQgetvalue( i, 0 );
+      }
+
+      if ( colRes.PQgetisnull( i, 1 ) == 0 ) {
+        ++layerProperty.nSpCols;
+      }
     }
   }
   else
   {
     QgsMessageLog::logMessage( tr( "SQL:%1\nresult:%2\nerror:%3\n" ).arg( sql ).arg( colRes.PQresultStatus() ).arg( colRes.PQresultErrorMessage() ), tr( "PostGIS" ) );
   }
 
-  return cols;
 }
 
 bool QgsPostgresConn::getTableInfo( bool searchGeometryColumnsOnly, bool searchPublicOnly, bool allowGeometrylessTables )
@@ -404,15 +413,12 @@ bool QgsPostgresConn::getTableInfo( bool searchGeometryColumnsOnly, bool searchP
       layerProperty.types = QList<QGis::WkbType>() << ( QgsPostgresConn::wkbTypeFromPostgis( type ) );
       layerProperty.srids = QList<int>() << srid;
       layerProperty.sql = "";
+      addColumnInfo( layerProperty, schemaName, tableName, relkind == "v" );
 
-      if ( relkind == "v" )
+      if ( relkind == "v" && layerProperty.pkCols.empty() )
       {
-        layerProperty.pkCols = pkCandidates( schemaName, tableName );
-        if ( layerProperty.pkCols.isEmpty() )
-        {
-          QgsDebugMsg( "no key columns found." );
-          continue;
-        }
+        QgsDebugMsg( "no key columns found." );
+        continue;
       }
 
       mLayersSupported << layerProperty;
@@ -522,14 +528,11 @@ bool QgsPostgresConn::getTableInfo( bool searchGeometryColumnsOnly, bool searchP
         Q_ASSERT( !"Unknown geometry type" );
       }
 
-      if ( relkind == "v" )
+      addColumnInfo( layerProperty, schemaName, tableName, relkind == "v" );
+      if ( relkind == "v" && layerProperty.pkCols.empty() )
       {
-        layerProperty.pkCols = pkCandidates( schemaName, tableName );
-        if ( layerProperty.pkCols.isEmpty() )
-        {
-          QgsDebugMsg( "no key columns found." );
-          continue;
-        }
+        QgsDebugMsg( "no key columns found." );
+        continue;
       }
 
       layerProperty.sql = "";
@@ -583,7 +586,7 @@ bool QgsPostgresConn::getTableInfo( bool searchGeometryColumnsOnly, bool searchP
       layerProperty.tableName = table;
       layerProperty.geometryColName = QString::null;
       layerProperty.geometryColType = sctNone;
-      layerProperty.pkCols = relkind == "v" ? pkCandidates( schema, table ) : QStringList();
+      addColumnInfo( layerProperty, schema, table, relkind == "v" );
       layerProperty.sql = "";
 
       mLayersSupported << layerProperty;

src/providers/postgres/qgspostgresconn.h

@@ -53,10 +53,19 @@ struct QgsPostgresLayerProperty
   QgsPostgresGeometryColumnType geometryColType;
   QStringList                   pkCols;
   QList<int>                    srids;
+  unsigned int                  nSpCols;
   QString                       sql;
 
+
+  // TODO: rename this !
   int size() const { Q_ASSERT( types.size() == srids.size() ); return types.size(); }
 
+  QString   defaultName() const {
+    QString n = tableName;
+    if ( nSpCols > 1 ) n += "." + geometryColName;
+    return n;
+  }
+
   QgsPostgresLayerProperty at( int i ) const
   {
     QgsPostgresLayerProperty property;
@@ -70,6 +79,7 @@ struct QgsPostgresLayerProperty
     property.geometryColName = geometryColName;
     property.geometryColType = geometryColType;
     property.pkCols          = pkCols;
+    property.nSpCols         = nSpCols;
     property.sql             = sql;
 
     return property;
@@ -93,14 +103,15 @@ struct QgsPostgresLayerProperty
       sridString += QString::number( srid );
     }
 
-    return QString( "%1.%2.%3 type=%4 srid=%5 pkCols=%6 sql=%7" )
+    return QString( "%1.%2.%3 type=%4 srid=%5 pkCols=%6 sql=%7 nSpCols=%8" )
            .arg( schemaName )
            .arg( tableName )
            .arg( geometryColName )
            .arg( typeString )
            .arg( sridString )
            .arg( pkCols.join( "|" ) )
-           .arg( sql );
+           .arg( sql )
+           .arg( nSpCols );
   }
 #endif
 };
@@ -215,9 +226,6 @@ class QgsPostgresConn : public QObject
     /** Gets information about the spatial tables */
     bool getTableInfo( bool searchGeometryColumnsOnly, bool searchPublicOnly, bool allowGeometrylessTables );
 
-    /** get primary key candidates (all int4 columns) */
-    QStringList pkCandidates( QString schemaName, QString viewName );
-
     qint64 getBinaryInt( QgsPostgresResult &queryResult, int row, int col );
 
     QString fieldExpression( const QgsField &fld );
@@ -292,6 +300,9 @@ class QgsPostgresConn : public QObject
     static QMap<QString, QgsPostgresConn *> sConnectionsRW;
     static QMap<QString, QgsPostgresConn *> sConnectionsRO;
 
+    /** count number of spatial columns in a given relation */
+    void addColumnInfo( QgsPostgresLayerProperty& layerProperty, const QString& schemaName, const QString& viewName, bool fetchPkCandidates );
+
     //! List of the supported layers
     QVector<QgsPostgresLayerProperty> mLayersSupported;
 

src/providers/postgres/qgspostgresdataitems.cpp

@@ -375,7 +375,7 @@ void QgsPGSchemaItem::addLayer( QgsPostgresLayerProperty layerProperty )
       tip = tr( "as geometryless table" );
   }
 
-  QgsPGLayerItem *layerItem = new QgsPGLayerItem( this, layerProperty.tableName, mPath + "/" + layerProperty.tableName, layerType, layerProperty );
+  QgsPGLayerItem *layerItem = new QgsPGLayerItem( this, layerProperty.defaultName(), mPath + "/" + layerProperty.tableName, layerType, layerProperty );
   layerItem->setToolTip( tip );
   addChild( layerItem );
 }