Error in saving polygon with openlayers-3 and geoserver 2.7?

Question

I'm using OpenLayers 3.8.2. I have wfs layer. I insert a feature. I save this feature as follow(I use geoserver 2.7-SNAPSHOT in server side):

var features = source.getFeatures();
var insertedArr = [];
var updateArr = [];
var deleteArr = [];

for (var i in features) {
    var state = features[i].getProperties().state;
    switch (state) {
        case "insert":
            console.log("------- INSERT -------")
            var feature = features[i];
            var properties = feature.getProperties();

            if (properties.boundedBy)
                delete properties.boundedBy;

            if (properties.the_geom)
                delete properties.the_geom;

            if (properties.geometry)
                delete properties.geometry;

            if (properties.controllerId)
                delete properties.controllerId;

            var geometry = feature.getGeometry().clone();
            geometry.transform("EPSG:3857", "EPSG:4326");

            newFeature = new ol.Feature({
                the_geom: geometry
            });
            newFeature.setGeometryName("the_geom");
            newFeature.setProperties(properties);
            newFeature.setId(feature.getId());

            insertedArr.push(newFeature);
            break;
        case "update":
            ...
            break
        case "delete":
            ...
            break;
    }
}

var wfs = new ol.format.WFS();

var node = wfs.writeTransaction(insertedArr, updateArr, deleteArr, {
    featureType: "mf",
    featurePrefix: 'Calk',
    featureNS: "http://itsme.calk.ir",
    version: '1.1.0',
    srsName: "EPSG:4326"
});

var s = new XMLSerializer();

var url = "http://localhost:8080/geoserver/wfs";

Ext.Ajax.request({
    url: 'proxy.cgi?url=' + encodeURIComponent(url),
    method: 'POST',
    xmlData: s.serializeToString(node),
    headers: {
        'Content-Type': 'text/xml'
    },
    success: function(response_) {
        response = response_;
    }
});

It send a request to server as follow:

<Transaction xmlns="http://www.opengis.net/wfs" service="WFS" version="1.1.0" 
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
             xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.1.0/wfs.xsd">
    <Insert>
        <mf xmlns="http://itsme.calk.ir">
            <the_geom>
                <Polygon xmlns="http://www.opengis.net/gml">
                    <exterior>
                        <LinearRing>
                            <posList>48.05419921875 37.30901407427592 ... 48.05419921875 37.30901407427592</posList>
                        </LinearRing>
                    </exterior>
                </Polygon>
            </the_geom>
            <region>MyRegion</region>
            <shape_len>10</shape_len>
        </mf>
    </Insert>
</Transaction>

But the server response as follow:

<ows:ExceptionReport xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:ows="http://www.opengis.net/ows" 
                     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.0.0" 
                     xsi:schemaLocation="http://www.opengis.net/ows 
                        http://192.168.3.2:8082/geoserver/schemas/ows/1.0.0/owsExceptionReport.xsd">
    <ows:Exception exceptionCode="InvalidParameterValue">
        <ows:ExceptionText>Error performing insert: java.lang.String cannot be cast to com.vividsolutions.jts.geom.Geometry</ows:ExceptionText>
    </ows:Exception>
</ows:ExceptionReport>

The discribefeatureType of geoserver's layer is as follow:

<xsd:schema xmlns:Calk="http://itsme.calk.ir" xmlns:gml="http://www.opengis.net/gml" 
            xmlns:xsd="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" 
            targetNamespace="http://itsme.calk.ir">

    <xsd:import namespace="http://www.opengis.net/gml" 
                schemaLocation="http://192.168.3.2:8082/geoserver/schemas/gml/3.1.1/base/gml.xsd"/>

    <xsd:complexType name="mfType">
        <xsd:complexContent>
            <xsd:extension base="gml:AbstractFeatureType">
                <xsd:sequence>
                    <xsd:element maxOccurs="1" minOccurs="0" name="region" nillable="true" type="xsd:string"/>
                    <xsd:element maxOccurs="1" minOccurs="0" name="shape_len" nillable="true" type="xsd:int"/>
                    <xsd:element maxOccurs="1" minOccurs="0" name="the_geom" nillable="true" type="gml:MultiSurfacePropertyType"/>
                </xsd:sequence>
            </xsd:extension>
        </xsd:complexContent>
    </xsd:complexType>
    <xsd:element name="mf" substitutionGroup="gml:_Feature" type="Calk:mfType"/>
</xsd:schema>

Where is the problem? Why server reply Error performing insert: java.lang.String cannot be cast to com.vividsolutions.jts.geom.Geometry?

Answer 1

It's occur because you are drawing a polygon, But server accept a multipolygon. When you define drawInteraction, you have to define it as follow:

drawInteraction = new ol.interaction.Draw({
   source: mySource,
   type: 'MultiPolygon'
});

Answer 2

The schema of your layer expects a gml:MultiSurfacePropertyType for the_geom field but you are filling the field with a Polygon. Check this thread.

I'm not sure if sending a MultiPolygon automatically converts to MultiSurface.

Try something like

newFeature = new ol.Feature({
    the_geom: OpenLayers.Geometry.MultiPolygon([geometry])
});