Allow setting list of attributes to exclude from json exports

python/core/qgsjsonutils.sip

@@ -55,15 +55,36 @@ class QgsJSONExporter
      * @param attributes list of attribute indexes, or an empty list to include all
      * attributes
      * @see attributes()
+     * @see setExcludedAttributes()
+     * @note Attributes excluded via setExcludedAttributes() take precedence over
+     * attributes specified by this method.
      */
     void setAttributes( const QgsAttributeList& attributes );
 
     /** Returns the list of attributes which will be included in the JSON exports, or
      * an empty list if all attributes will be included.
      * @see setAttributes()
+     * @see excludedAttributes()
+     * @note Attributes excluded via excludedAttributes() take precedence over
+     * attributes returned by this method.
      */
     QgsAttributeList attributes() const;
 
+    /** Sets a list of attributes to specifically exclude from the JSON exports. Excluded attributes
+     * take precedence over attributes included via setAttributes().
+     * @param attributes list of attribute indexes to exclude
+     * @see excludedAttributes()
+     * @see setAttributes()
+     */
+    void setExcludedAttributes( const QgsAttributeList& attributes );
+
+    /** Returns a list of attributes which will be specifically excluded from the JSON exports. Excluded attributes
+     * take precedence over attributes included via attributes().
+     * @see setExcludedAttributes()
+     * @see attributes()
+     */
+    QgsAttributeList excludedAttributes() const;
+
     /** Returns a GeoJSON string representation of a feature.
      * @param feature feature to convert
      * @param extraProperties map of extra attributes to include in feature's properties

src/core/qgsjsonutils.cpp

@@ -29,56 +29,29 @@ QgsJSONExporter::QgsJSONExporter( int precision, bool includeGeometry, bool incl
 QString QgsJSONExporter::exportFeature( const QgsFeature& feature, const QVariantMap& extraProperties,
                                         const QVariant& id ) const
 {
-  QString s = "{\n   \"type\":\"Feature\",\n";
-
-  // ID
-  s += QString( "   \"id\":%1" ).arg( !id.isValid() ? QString::number( feature.id() ) : QgsJSONUtils::encodeValue( id ) );
-
-  if ( mIncludeAttributes || mIncludeGeometry || !extraProperties.isEmpty() )
-    s += ",\n";
-  else
-    s += '\n';
-
-  const QgsGeometry* geom = feature.constGeometry();
-  if ( geom && !geom->isEmpty() && mIncludeGeometry )
-  {
-    QgsRectangle box = geom->boundingBox();
-
-    if ( QgsWKBTypes::flatType( geom->geometry()->wkbType() ) != QgsWKBTypes::Point )
-    {
-      s += QString( "   \"bbox\":[%1, %2, %3, %4],\n" ).arg( qgsDoubleToString( box.xMinimum(), mPrecision ),
-           qgsDoubleToString( box.yMinimum(), mPrecision ),
-           qgsDoubleToString( box.xMaximum(), mPrecision ),
-           qgsDoubleToString( box.yMaximum(), mPrecision ) );
-    }
-    s += "   \"geometry\":\n   ";
-    s += geom->exportToGeoJSON( mPrecision );
-    if ( mIncludeAttributes || !extraProperties.isEmpty() )
-      s += ",\n";
-    else
-      s += '\n';
-  }
+  //first step is to build up the properties list
+  QString properties;
 
+  int attributeCounter = 0;
   if ( mIncludeAttributes || !extraProperties.isEmpty() )
   {
     //read all attribute values from the feature
-    s += "   \"properties\":{\n";
-    int attributeCounter = 0;
+
 
     if ( mIncludeAttributes )
     {
       const QgsFields* fields = feature.fields();
 
       for ( int i = 0; i < fields->count(); ++i )
       {
-        if ( !mAttributeIndexes.isEmpty() && !mAttributeIndexes.contains( i ) )
+        if (( !mAttributeIndexes.isEmpty() && !mAttributeIndexes.contains( i ) ) || mExcludedAttributeIndexes.contains( i ) )
           continue;
 
         if ( attributeCounter > 0 )
-          s += ",\n";
+          properties += ",\n";
         QVariant val =  feature.attributes().at( i );
 
-        s += QString( "      \"%1\":%2" ).arg( fields->at( i ).name(), QgsJSONUtils::encodeValue( val ) );
+        properties += QString( "      \"%1\":%2" ).arg( fields->at( i ).name(), QgsJSONUtils::encodeValue( val ) );
 
         ++attributeCounter;
       }
@@ -90,18 +63,53 @@ QString QgsJSONExporter::exportFeature( const QgsFeature& feature, const QVarian
       for ( ; it != extraProperties.constEnd(); ++it )
       {
         if ( attributeCounter > 0 )
-          s += ",\n";
+          properties += ",\n";
 
-        s += QString( "      \"%1\":%2" ).arg( it.key(), QgsJSONUtils::encodeValue( it.value() ) );
+        properties += QString( "      \"%1\":%2" ).arg( it.key(), QgsJSONUtils::encodeValue( it.value() ) );
 
         ++attributeCounter;
       }
     }
+  }
+  bool hasProperties = attributeCounter > 0;
 
-    s += "\n   }\n";
+  QString s = "{\n   \"type\":\"Feature\",\n";
+
+  // ID
+  s += QString( "   \"id\":%1" ).arg( !id.isValid() ? QString::number( feature.id() ) : QgsJSONUtils::encodeValue( id ) );
+
+  if ( hasProperties || mIncludeGeometry )
+    s += ",\n";
+  else
+    s += '\n';
+
+  const QgsGeometry* geom = feature.constGeometry();
+  if ( geom && !geom->isEmpty() && mIncludeGeometry )
+  {
+    QgsRectangle box = geom->boundingBox();
+
+    if ( QgsWKBTypes::flatType( geom->geometry()->wkbType() ) != QgsWKBTypes::Point )
+    {
+      s += QString( "   \"bbox\":[%1, %2, %3, %4],\n" ).arg( qgsDoubleToString( box.xMinimum(), mPrecision ),
+           qgsDoubleToString( box.yMinimum(), mPrecision ),
+           qgsDoubleToString( box.xMaximum(), mPrecision ),
+           qgsDoubleToString( box.yMaximum(), mPrecision ) );
+    }
+    s += "   \"geometry\":\n   ";
+    s += geom->exportToGeoJSON( mPrecision );
+    if ( hasProperties )
+      s += ",\n";
+    else
+      s += '\n';
+  }
+
+  if ( hasProperties )
+  {
+    //read all attribute values from the feature
+    s += "   \"properties\":{\n" + properties + "\n   }\n";
   }
 
-  s += "}";
+  s += '}';
 
   return s;
 }

src/core/qgsjsonutils.h

@@ -74,15 +74,36 @@ class CORE_EXPORT QgsJSONExporter
      * @param attributes list of attribute indexes, or an empty list to include all
      * attributes
      * @see attributes()
+     * @see setExcludedAttributes()
+     * @note Attributes excluded via setExcludedAttributes() take precedence over
+     * attributes specified by this method.
      */
     void setAttributes( const QgsAttributeList& attributes ) { mAttributeIndexes = attributes; }
 
     /** Returns the list of attributes which will be included in the JSON exports, or
      * an empty list if all attributes will be included.
      * @see setAttributes()
+     * @see excludedAttributes()
+     * @note Attributes excluded via excludedAttributes() take precedence over
+     * attributes returned by this method.
      */
     QgsAttributeList attributes() const { return mAttributeIndexes; }
 
+    /** Sets a list of attributes to specifically exclude from the JSON exports. Excluded attributes
+     * take precedence over attributes included via setAttributes().
+     * @param attributes list of attribute indexes to exclude
+     * @see excludedAttributes()
+     * @see setAttributes()
+     */
+    void setExcludedAttributes( const QgsAttributeList& attributes ) { mExcludedAttributeIndexes = attributes; }
+
+    /** Returns a list of attributes which will be specifically excluded from the JSON exports. Excluded attributes
+     * take precedence over attributes included via attributes().
+     * @see setExcludedAttributes()
+     * @see attributes()
+     */
+    QgsAttributeList excludedAttributes() const { return mExcludedAttributeIndexes; }
+
     /** Returns a GeoJSON string representation of a feature.
      * @param feature feature to convert
      * @param extraProperties map of extra attributes to include in feature's properties
@@ -100,8 +121,12 @@ class CORE_EXPORT QgsJSONExporter
     int mPrecision;
 
     //! List of attribute indexes to include in export, or empty list to include all attributes
+    //! @see mExcludedAttributeIndexes
     QgsAttributeList mAttributeIndexes;
 
+    //! List of attribute indexes to exclude from export
+    QgsAttributeList mExcludedAttributeIndexes;
+
     //! Whether to include geometry in JSON export
     bool mIncludeGeometry;
 
@@ -139,24 +164,6 @@ class CORE_EXPORT QgsJSONUtils
      */
     static QgsFields stringToFields( const QString& string, QTextCodec* encoding );
 
-    /** Returns a GeoJSON string representation of a feature.
-     * @param feature feature to convert
-     * @param precision maximum number of decimal places to use for geometry coordinates
-     * @param attrIndexes list of attribute indexes to include in GeoJSON, or an empty list to include
-     * all attributes
-     * @param includeGeom set to false to avoid including the geometry representation in the JSON output
-     * @param includeAttributes set to false to avoid including any attribute values in the JSON output
-     * @param id optional ID to use as GeoJSON feature's ID instead of input feature's ID. If omitted, feature's
-     * ID is used.
-     * @returns GeoJSON string
-     */
-    static QString featureToGeoJSON( const QgsFeature& feature,
-                                     int precision = 17,
-                                     const QgsAttributeList& attrIndexes = QgsAttributeList(),
-                                     bool includeGeom = true,
-                                     bool includeAttributes = true,
-                                     const QVariant& id = QVariant() );
-
     /** Encodes a value to a JSON string representation, adding appropriate quotations and escaping
      * where required.
      * @param value value to encode

tests/src/python/test_qgsjsonutils.py

@@ -198,6 +198,63 @@ def testJSONExporter(self):
         self.assertEqual(exporter.exportFeature(feature), expected)
         exporter.setAttributes([])
 
+        # text excluding attributes
+
+        exporter.setExcludedAttributes([1])
+        self.assertEqual(exporter.excludedAttributes(), [1])
+        expected = """{
+   "type":"Feature",
+   "id":5,
+   "geometry":
+   {"type": "Point", "coordinates": [5, 6]},
+   "properties":{
+      "name":"Valsier Peninsula",
+      "population":198
+   }
+}"""
+        self.assertEqual(exporter.exportFeature(feature), expected)
+
+        exporter.setExcludedAttributes([1, 2])
+        self.assertEqual(exporter.excludedAttributes(), [1, 2])
+        expected = """{
+   "type":"Feature",
+   "id":5,
+   "geometry":
+   {"type": "Point", "coordinates": [5, 6]},
+   "properties":{
+      "name":"Valsier Peninsula"
+   }
+}"""
+        self.assertEqual(exporter.exportFeature(feature), expected)
+
+        exporter.setExcludedAttributes([0, 1, 2])
+        self.assertEqual(exporter.excludedAttributes(), [0, 1, 2])
+        expected = """{
+   "type":"Feature",
+   "id":5,
+   "geometry":
+   {"type": "Point", "coordinates": [5, 6]}
+}"""
+        self.assertEqual(exporter.exportFeature(feature), expected)
+
+        # test that excluded attributes take precedence over included
+
+        exporter.setAttributes([1, 2])
+        exporter.setExcludedAttributes([0, 1])
+        expected = """{
+   "type":"Feature",
+   "id":5,
+   "geometry":
+   {"type": "Point", "coordinates": [5, 6]},
+   "properties":{
+      "population":198
+   }
+}"""
+        self.assertEqual(exporter.exportFeature(feature), expected)
+
+        exporter.setAttributes([])
+        exporter.setExcludedAttributes([])
+
         # test excluding geometry
         exporter.setIncludeGeometry(False)
         self.assertEqual(exporter.includeGeometry(), False)