WFS Schema Mapping¶

Schema customization¶

The GeoServer WFS supports a limited amount of customization with regard to schema output. A custom schema can be used to:

• Limit the attributes which are exposed in the feature type schema
• Changing the types of attributes in the schema
• Change the structure of the schema, for example changing the base feature type

A mapped schema is customized by creating a file called schema.xsd in the appropriate feature type directory of the GeoServer data directory. As an simple example consider the use case of limiting the exposed attributes in the above dataset.

It is useful to start with the default output as a base as it is a complete schema. With the feature type schema shown above, a GetFeature request would result in features that look like the following:

<topp:myDataset gml:id="myDataset.1">
      <topp:intProperty>1</topp:intProperty>
      <topp:stringProperty>one</topp:stringProperty>
      <topp:floatProperty>1.1</topp:floatProperty>
      <topp:geometry>
        <gml:Point srsName="urn:x-ogc:def:crs:EPSG:4326">
          <gml:pos>1.0 1.0</gml:pos>
        </gml:Point>
      </topp:geometry>
    </topp:myDataset>

Now consider the case of removing the floatProperty from attribute. To achieve this:

1. The original schema is modified and the floatProperty is removed, resulting in the following type definition:

   <xsd:complexType name="myDatasetType">
      <xsd:complexContent>
        <xsd:extension base="gml:AbstractFeatureType">
          <xsd:sequence>
            <xsd:element maxOccurs="1" minOccurs="0" name="intProperty" nillable="true" type="xsd:int"/>
            <xsd:element maxOccurs="1" minOccurs="0" name="stringProperty" nillable="true" type="xsd:string"/>
            <!-- remove the floatProperty element
            <xsd:element maxOccurs="1" minOccurs="0" name="floatProperty" nillable="true" type="xsd:double"/>
            -->
            <xsd:element maxOccurs="1" minOccurs="0" name="geometry" nillable="true" type="gml:PointPropertyType"/>
          </xsd:sequence>
        </xsd:extension>
      </xsd:complexContent>
   </xsd:complexType>
   

2. The result is saved in a file named schema.xsd.

3. The schema.xsd file is copied into the feature type directory for the topp:myDataset:

   copy schema.xsd $GEOSERVER_DATA_DIR/workspaces/<workspace>/<datastore>/myDataset/

   Where <workspace> is the name of the workspace containing your datastore and <datastore> is the name of the data store which contains myDataset

In order for the new schema to to be picked up by GeoServer the configuration must be reloaded. This cab be done by logging into the admin interface and clicking the Load button the Config page. Or alternatively by restarting the entire Server.

Another DescribeFeatureType request for the topp:myDataset type now results in the floatProperty element being absent:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            xmlns:gml="http://www.opengis.net/gml"
            xmlns:topp="http://www.openplans.org/topp"
            targetNamespace="http://www.openplans.org/topp"
            elementFormDefault="qualified">

           <xsd:import namespace="http://www.opengis.net/gml" schemaLocation="http://localhost:8080/geoserver/schemas/gml/3.1.1/base/gml.xsd"/>

           <xsd:complexType name="myDatasetType">
             <xsd:complexContent>
               <xsd:extension base="gml:AbstractFeatureType">
                 <xsd:sequence>
                   <xsd:element maxOccurs="1" minOccurs="0" name="intProperty" nillable="true" type="xsd:int"/>
                   <xsd:element maxOccurs="1" minOccurs="0" name="stringProperty" nillable="true" type="xsd:string"/>
                   <xsd:element maxOccurs="1" minOccurs="0" name="geometry" nillable="true" type="gml:PointPropertyType"/>
                 </xsd:sequence>
               </xsd:extension>
             </xsd:complexContent>
           </xsd:complexType>

           <xsd:element name="myDataset" substitutionGroup="gml:_Feature" type="topp:myDatasetType"/>

   </xsd:schema>

Another GetFeature request now results in features in which the floatProperty is absent:

<topp:myDataset gml:id="myDataset.1">
  <topp:intProperty>1</topp:intProperty>
  <topp:stringProperty>one</topp:stringProperty>
  <topp:geometry>
    <gml:Point srsName="urn:x-ogc:def:crs:EPSG:4326">
      <gml:pos>1.0 1.0</gml:pos>
    </gml:Point>
  </topp:geometry>
</topp:myDataset>

Type changing¶

Schema customization can be used to do a limited amount of type changing. Limited by the fact that a changed type must be in the same “domain” as the original type. For example integers types must be changed to integer types, temporal types to temporal types, etc...

The most common case is for geometry attributes. Often it is the case that the underlying dataset does not have the metadata necessary to report the specific type (Point,LineString,Polygon, etc...) of a geometry attribute. In these cases the automatic schema mapping would result in an element particle like the following:

<xsd:element maxOccurs="1" minOccurs="0" name="geometry" nillable="true " type="gml:GeometryPropertyType"/>

However it is often the case that the user knows the specific type of the geometry, for example Point. The above element could be changed to:

<xsd:element maxOccurs="1" minOccurs="0" name="geometry" nillable="true " type="gml:PointPropertyType"/>