Parse Google Maps GeocodeResponse XML and extract values

Question

I'm making a http request to GoogleMaps API and the XML I get back is listed below.

I'm trying to assign the LAT and LON values to a string but I'm getting a "Null Reference Exception" Object reference not set to an instance of an object. on the line "string lat = childnode...

I based my attempt in this question/answer

When I look in the nodeList in the debugger all the details from the XML are in the Results View.

Any Ideas what I'm doing wrong?

Here is the problem code.

// Parse the XML
XmlDocument doc = new XmlDocument();
doc.LoadXml(responseFromServer);

XmlNodeList nodeList = doc.SelectNodes("/*[local-name() = 'GeocodeResponse']/*[local-name() = 'result']");

if (nodeList != null)
{
    foreach (XmlNode childNode in nodeList)
    {
        string lat = childNode.SelectSingleNode("//*[local-name() = 'geometry/location/lat']").InnerText;
        string lon = childNode.SelectSingleNode("//*[local-name() = 'geometry/location/lon']").InnerText;
        string locationType = childNode.SelectSingleNode("//*[local-name() = 'geometry/location_type']").InnerText;
    }
}

Here is an example of the XML that Google Maps Returns

Address changed to protect the innocent :)

<?xml version=\"1.0\" encoding=\"UTF-8\"?>
<GeocodeResponse>
 <status>OK</status>
 <result>
    <type>street_address</type>
    <formatted_address>48 Johnson Ave, Wiley Park NSW 2195, Australia</formatted_address>
    <address_component>
        <long_name>48</long_name>
        <short_name>48</short_name>
        <type>street_number</type>
    </address_component>
    <address_component>
        <long_name>Johnson Avenue</long_name>
        <short_name>Johnson Ave</short_name>
        <type>route</type>
        </address_component>
    <address_component>
        <long_name>Wiley Park</long_name>
        <short_name>Wiley Park</short_name>
        <type>locality</type>
        <type>political</type>
    </address_component>
    <address_component>
        <long_name>Canterbury City Council</long_name>
        <short_name>Canterbury</short_name>
        <type>administrative_area_level_2</type>
        <type>political</type>
    </address_component>
    <address_component>
        <long_name>New South Wales</long_name>
        <short_name>NSW</short_name>
        <type>administrative_area_level_1</type>
        <type>political</type>
    </address_component>
    <address_component>
        <long_name>Australia</long_name>
        <short_name>AU</short_name>
        <type>country</type>
        <type>political</type>
    </address_component>
    <address_component>
        <long_name>2195</long_name>
        <short_name>2195</short_name>
        <type>postal_code</type>
    </address_component>
    <geometry>
        <location>
            <lat>-33.9279554</lat>
            <lng>151.0688625</lng>
        </location>
        <location_type>ROOFTOP</location_type>
        <viewport>
            <southwest>
                <lat>-33.9293044</lat>
                <lng>151.0675135</lng>
            </southwest>
            <northeast>
                <lat>-33.9266064</lat>
                <lng>151.0702115</lng>
            </northeast>
        </viewport>
    </geometry>
    <partial_match>true</partial_match>
        <place_id>ChIJkUHpDOe7EmsRGapwFB6s9Dw</place_id>
    </result>
</GeocodeResponse>

EDIT: It is looking to me like I haven't specified the path to the nodes I want correctly. Not sure what I should change.

Ibrahim Malluf · Accepted Answer · 2016-11-28 05:53:58Z

0

Use a simpler XPath call:

            XmlDocument doc = new XmlDocument();
            doc.Load("google.xml");

            XmlNodeList nodeList = doc.SelectNodes("/*[local-name() = 'GeocodeResponse']/*[local-name() = 'result']");

            if (nodeList != null)
            {
                foreach (XmlNode childNode in nodeList)
                {
                    string lat = childNode.SelectSingleNode("geometry/location/lat").InnerText;
                    string lon = childNode.SelectSingleNode("geometry/location/lng").InnerText;
                    string locationType = childNode.SelectSingleNode("geometry/location_type").InnerText;
                }
            }

Also...the Longitude node is 'lgn' not lon

answered Nov 28, 2016 at 5:53

Ibrahim Malluf

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1 Comment

David P Over a year ago

Perfect :) I had already spoted the lon lng problem but that /*[local-name stuff was just confusing me. What you have makes much more sense seeing as how I'd already specified that in the declaration. Now I have to try and pick out the City Council Name but I'll try and figure it out for myself. Thanks for your assistance.

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