Add option to postgres provider to drop length constraints on character fields

Author: nyalldawson

src/providers/postgres/qgspostgresprovider.cpp

@@ -2767,9 +2767,17 @@ bool QgsPostgresProvider::getGeometryDetails()
   return mValid;
 }
 
-bool QgsPostgresProvider::convertField( QgsField &field )
+bool QgsPostgresProvider::convertField( QgsField &field , const QMap<QString, QVariant>* options )
 {
-  QString fieldType = "varchar"; //default to string
+  //determine field type to use for strings
+  QString stringFieldType = "varchar";
+  if ( options->contains( "dropStringConstraints" ) && options->value( "dropStringConstraints" ).toBool() )
+  {
+    //drop string length constraints by using PostgreSQL text type for strings
+    stringFieldType = "text";
+  }
+
+  QString fieldType = stringFieldType; //default to string
   int fieldSize = field.length();
   int fieldPrec = field.precision();
   switch ( field.type() )
@@ -2788,7 +2796,7 @@ bool QgsPostgresProvider::convertField( QgsField &field )
       break;
 
     case QVariant::String:
-      fieldType = "varchar";
+      fieldType = stringFieldType;
       fieldPrec = -1;
       break;
 
@@ -2900,7 +2908,7 @@ QgsVectorLayerImport::ImportError QgsPostgresProvider::createEmptyLayer(
       {
         // found, get the field type
         QgsField fld = fields[fldIdx];
-        if ( convertField( fld ) )
+        if ( convertField( fld, options ) )
         {
           primaryKeyType = fld.typeName();
         }
@@ -3050,7 +3058,7 @@ QgsVectorLayerImport::ImportError QgsPostgresProvider::createEmptyLayer(
         fld.setName( fld.name().toLower() );
       }
 
-      if ( !convertField( fld ) )
+      if ( !convertField( fld, options ) )
       {
         if ( errorMessage )
           *errorMessage = QObject::tr( "Unsupported type for field %1" ).arg( fld.name() );

src/providers/postgres/qgspostgresprovider.h

@@ -47,7 +47,12 @@ class QgsPostgresProvider : public QgsVectorDataProvider
 
   public:
 
-    /** Import a vector layer into the database */
+    /** Import a vector layer into the database
+     * @param options options for provider, specified via a map of option name
+     * to value. Valid options are lowercaseFieldNames (set to true to convert
+     * field names to lowercase), dropStringConstraints (set to true to remove
+     * length constraints on character fields).
+    */
     static QgsVectorLayerImport::ImportError createEmptyLayer(
       const QString& uri,
       const QgsFields &fields,
@@ -324,7 +329,7 @@ class QgsPostgresProvider : public QgsVectorDataProvider
     bool loadFields();
 
     /** convert a QgsField to work with PG */
-    static bool convertField( QgsField &field );
+    static bool convertField( QgsField &field, const QMap<QString, QVariant> *options = 0 );
 
     /**Parses the enum_range of an attribute and inserts the possible values into a stringlist
     @param enumValues the stringlist where the values are appended