Getting Feature names from WFS in C++

Question

to start off with:

Coding in C++

Using WFS Version 1.0.0

Using QT 5.4.1

Windows 8 Latest versions

I'm trying to read in a WFS in code via Gdal compiled with Xerces - I'm able to read the GML files so I can pull spatial point/lines/polygons etc. But I'm not too sure how I do this with the feature names/layers. Any help?]

This is what I'm trying to get: The Cities layer name and Continents layer name, but via code.

<schema xmlns:ms="http://mapserver.gis.umn.edu/mapserver"
xmlns:ogc="http://www.opengis.net/ogc" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns="http://www.w3.org/2001/XMLSchema" xmlns:gml="http://www.opengis.net/gml" 
targetNamespace="http://mapserver.gis.umn.edu/mapserver"elementFormDefault="qualified" version="0.1">
<import namespace="http://www.opengis.net/gml"     
schemaLocation="http://schemas.opengis.net/gml/2.1.2/feature.xsd"/>
<element name="continents" type="ms:continentsType"      
substitutionGroup="gml:_Feature"/>

<complexType name="continentsType">
<complexContent>
<extension base="gml:AbstractFeatureType">
<sequence>
<element name="msGeometry" type="gml:GeometryPropertyType" minOccurs="0"maxOccurs="1"/>
<element name="NA2DESC" type="string"/>
<element name="NA3DESC" type="string"/>
</sequence>
</extension>
</complexContent>
</complexType>
<element name="cities" type="ms:citiesType" substitutionGroup="gml:_Feature"/>
<complexType name="citiesType">
<complexContent>
<extension base="gml:AbstractFeatureType">
<sequence>
<element name="msGeometry" type="gml:GeometryPropertyType" minOccurs="0" maxOccurs="1"/>
<element name="POPULATION" type="string"/>
<element name="NAME" type="string"/>
</sequence>
</extension>
</complexContent>
</complexType>
</schema>

You can call the Features type by using this WFS GET request http://demo.mapserver.org/cgi-bin/wfs?SERVICE=WFS&VERSION=1.0.0&REQUEST=DescribeFeatureType

Answer 1

After a bit of tinkering with my program I've managed to pull the Layer name and its elements/variables!

See code below on how to do it:

void main()
{
    // Register your drivers
    OGRRegisterAll();

   // Get your wfs here - (M_DATASOURCE IN HEADER)
   m_datasource = OGRSFDriverRegistrar::Open(m_ui->m_line_wfs_name->text().toStdString().c_str(), false);

   // Call the function to start it all off
   readShapeFile();
}

 // This functions finds all the possible layers
std::vector<std::string> DialogWfsReader::getLayerName()
{
     // This vector holds all the layers that we have found
     std::vector<std::string> layer_names;

     // Loop for the ammount of layers in ogr_datasource - this is where the .shp is loaded into
     for(int i = 0; i < m_datasource->GetLayerCount(); i++)
     {
         // This gets the current layer
         auto layer = m_datasource->GetLayer(i);
         // Then gets the current layer name from layer
         layer_names.push_back(layer->GetName());
     }

     // Then return the layer names
     return layer_names;
}

void DialogWfsReader::readShapeFile()
{

// Creating a pointer to the layer
OGRLayer *poLayer;

// If this is a nullptr then the file has not opened
if(m_datasource  == nullptr)
{
    // Put your error codes here :)
    // Means your can not open that WFS/SHP file!
}
else
{

    // Loop over all the layer names
    for(const auto& layer_name : getLayerName())
    {
        // Get layers for each name
        poLayer = m_datasource ->GetLayerByName(layer_name.c_str());

        // Reset your reading, you need to start from the beginning!
        poLayer->ResetReading();

        // Varible to hold the feature
        OGRFeature* feature;


        // Start looping all the features, and assign it to feature!
        while((feature = poLayer->GetNextFeature()) != nullptr)
        {
            // Get some more layer stuff
            OGRFeatureDefn *poFDefn = poLayer->GetLayerDefn();

            /// This is the layer name - For example "Cities"
            poLayer->GetName();

            /// Start getting all the fields for that layer name
            for(int iField = 0; iField < poFDefn->GetFieldCount(); iField++ )
            {
                //Set poFieldDefn to the current field in the loop
                OGRFieldDefn *poFieldDefn = poFDefn->GetFieldDefn( iField );

                /// This is where you get all your elements/varibles
                /// E.G CityName, CityPopulation , CityId etc....
                poFieldDefn->GetNameRef();
            }
        }
    }
}

}