[feature][expression] Add geometry_type function

Returns the high-level type of a geometry (Point/Line/Polygon)
qgis · Jan 6, 2022 · 47715fe · 47715fe
1 parent 3c001de
commit 47715fe
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diff --git a/resources/function_help/json/geometry_type b/resources/function_help/json/geometry_type
@@ -0,0 +1,12 @@
+{
+  "name": "geometry_type",
+  "type": "function",
+  "groups": ["GeometryGroup"],
+  "description": "Returns a string value describing the type of a geometry (Point, Line or Polygon)",
+  "arguments": [ {"arg":"geometry","description":"a geometry"}],
+  "examples": [ { "expression":"geometry_type( geom_from_wkt( 'LINESTRING(2 5, 3 6, 4 8)') )", "returns":"'Line'"},
+  { "expression":"geometry_type( geom_from_wkt( 'MULTILINESTRING((2 5, 3 6, 4 8), (1 1, 0 0))') )", "returns":"'Line'"},
+  { "expression":"geometry_type( geom_from_wkt( 'POINT(2 5)') )", "returns":"'Point'"},
+  { "expression":"geometry_type( geom_from_wkt( 'POLYGON((-1 -1, 4 0, 4 2, 0 2, -1 -1))') )", "returns":"'Polygon'"}
+  ]
+}
diff --git a/src/core/expression/qgsexpressionfunction.cpp b/src/core/expression/qgsexpressionfunction.cpp
@@ -3822,6 +3822,15 @@ static QVariant fcnBoundsHeight( const QVariantList &values, const QgsExpression
   return QVariant::fromValue( geom.boundingBox().height() );
 }
 
+static QVariant fcnGeometryType( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )
+{
+  const QgsGeometry geom = QgsExpressionUtils::getGeometry( values.at( 0 ), parent );
+  if ( geom.isNull() )
+    return QVariant();
+
+  return QgsWkbTypes::geometryDisplayString( geom.type() );
+}
+
 static QVariant fcnXMin( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )
 {
   QgsGeometry geom = QgsExpressionUtils::getGeometry( values.at( 0 ), parent );
@@ -7540,6 +7549,7 @@ const QList<QgsExpressionFunction *> &QgsExpression::Functions()
     functions << yAtFunc;
 
     functions
+        << new QgsStaticExpressionFunction( QStringLiteral( "geometry_type" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ), fcnGeometryType, QStringLiteral( "GeometryGroup" ) )
         << new QgsStaticExpressionFunction( QStringLiteral( "x_min" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ), fcnXMin, QStringLiteral( "GeometryGroup" ), QString(), false, QSet<QString>(), false, QStringList() << QStringLiteral( "xmin" ) )
         << new QgsStaticExpressionFunction( QStringLiteral( "x_max" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ), fcnXMax, QStringLiteral( "GeometryGroup" ), QString(), false, QSet<QString>(), false, QStringList() << QStringLiteral( "xmax" ) )
         << new QgsStaticExpressionFunction( QStringLiteral( "y_min" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "geometry" ) ), fcnYMin, QStringLiteral( "GeometryGroup" ), QString(), false, QSet<QString>(), false, QStringList() << QStringLiteral( "ymin" ) )

diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
@@ -999,6 +999,12 @@ class TestQgsExpression: public QObject
       QTest::newRow( "geom_to_wkb not geom" ) << "geom_to_wkt(geom_from_wkb(geom_to_wkb('a')))" << true << QVariant();
       QTest::newRow( "geom_from_wkb not geom" ) << "geom_to_wkt(geom_from_wkb(make_point(4,5)))" << true << QVariant();
       QTest::newRow( "geom_from_wkb null" ) << "geom_to_wkt(geom_from_wkb(NULL))" << false << QVariant();
+      QTest::newRow( "geometry_type not geom" ) << "geometry_type('g')" << true << QVariant();
+      QTest::newRow( "geometry_type null" ) << "geometry_type(NULL)" << false << QVariant();
+      QTest::newRow( "geometry_type point" ) << "geometry_type(geom_from_wkt('POINT(1 2)'))" << false << QVariant( QStringLiteral( "Point" ) );
+      QTest::newRow( "geometry_type polygon" ) << "geometry_type(geom_from_wkt('POLYGON((-1 -1, 4 0, 4 2, 0 2, -1 -1))'))" << false << QVariant( QStringLiteral( "Polygon" ) );
+      QTest::newRow( "geometry_type line" ) << "geometry_type(geom_from_wkt('LINESTRING(0 0, 1 1, 2 2)'))" << false << QVariant( QStringLiteral( "Line" ) );
+      QTest::newRow( "geometry_type multipoint" ) << "geometry_type(geom_from_wkt('MULTIPOINT((0 1),(0 0))'))" << false << QVariant( QStringLiteral( "Point" ) );
       QTest::newRow( "num_points" ) << "num_points(geom_from_wkt('GEOMETRYCOLLECTION(LINESTRING(0 0, 1 0),POINT(6 5))'))" << false << QVariant( 3 );
       QTest::newRow( "num_interior_rings not geom" ) << "num_interior_rings('g')" << true << QVariant();
       QTest::newRow( "num_interior_rings null" ) << "num_interior_rings(NULL)" << false << QVariant();