Need help with reading XML files

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As part of an application I am making to display weather and forecasts to the user through the Met Office' DataPoint service I have to read the files containing the weather data which are in XML format. I have been trying for days to do this and have had no success so I thought I would ask here. The XML file I need to get specific data from is this:

XML

<Layers type="Observation">
    <BaseUrl forServiceTimeFormat="Times">       
    <!--URL goes here-->
    </BaseUrl>
    <Layer displayName="Lightning">
        <Service name="OBSERVATIONS">
            <LayerName>ATDNET_Sferics</LayerName>
            <ImageFormat>png</ImageFormat>
            <Times>
                <Time>2013-08-06T13:45:00</Time>
                <Time>2013-08-06T13:30:00</Time>
                <Time>2013-08-06T13:15:00</Time>
                <Time>2013-08-06T13:00:00</Time>
                <Time>2013-08-06T12:45:00</Time>
                <Time>2013-08-06T12:30:00</Time>
                <Time>2013-08-06T12:15:00</Time>
                <Time>2013-08-06T12:00:00</Time>
                <Time>2013-08-06T11:45:00</Time>
                <Time>2013-08-06T11:30:00</Time>
                <Time>2013-08-06T11:15:00</Time>
                <Time>2013-08-06T11:00:00</Time>
                <Time>2013-08-06T10:45:00</Time>
            </Times>
        </Service>
    </Layer>
    <Layer displayName="SatelliteIR">
        <Service name="OBSERVATIONS">
            <LayerName>SATELLITE_Infrared_Fulldisk</LayerName>
            <ImageFormat>png</ImageFormat>
            <Times>
                <Time>2013-08-06T12:00:00</Time>
                <Time>2013-08-06T09:00:00</Time>
                <Time>2013-08-06T06:00:00</Time>
                <Time>2013-08-06T03:00:00</Time>
                <Time>2013-08-06T00:00:00</Time>
                <Time>2013-08-05T21:00:00</Time>
                <Time>2013-08-05T18:00:00</Time>
                <Time>2013-08-05T15:00:00</Time>
                <Time>2013-08-05T12:00:00</Time>
            </Times>
        </Service>
    </Layer>
    <Layer displayName="SatelliteVis">
        <Service name="OBSERVATIONS">
            <LayerName>SATELLITE_Visible_N_Section</LayerName>
            <ImageFormat>png</ImageFormat>
            <Times>
                <Time>2013-08-06T12:00:00</Time>
                <Time>2013-08-06T09:00:00</Time>
                <Time>2013-08-06T06:00:00</Time>
                <Time>2013-08-06T03:00:00</Time>
                <Time>2013-08-06T00:00:00</Time>
                <Time>2013-08-05T21:00:00</Time>
                <Time>2013-08-05T18:00:00</Time>
                <Time>2013-08-05T15:00:00</Time>
                <Time>2013-08-05T12:00:00</Time>
            </Times>
        </Service>
    </Layer>
    <Layer displayName="Rainfall">
        <Service name="OBSERVATIONS">
            <LayerName>RADAR_UK_Composite_Highres</LayerName>
            <ImageFormat>png</ImageFormat>
            <Times>
                <Time>2013-08-06T13:45:00</Time>
                <Time>2013-08-06T13:30:00</Time>
                <Time>2013-08-06T13:15:00</Time>
                <Time>2013-08-06T13:00:00</Time>
                <Time>2013-08-06T12:45:00</Time>
                <Time>2013-08-06T12:30:00</Time>
                <Time>2013-08-06T12:15:00</Time>
                <Time>2013-08-06T12:00:00</Time>
                <Time>2013-08-06T11:45:00</Time>
                <Time>2013-08-06T11:30:00</Time>
                <Time>2013-08-06T11:15:00</Time>
                <Time>2013-08-06T11:00:00</Time>
                <Time>2013-08-06T10:45:00</Time>
            </Times>
        </Service>
    </Layer>
</Layers>

So my question is how would I read the XML file and put the list of the 9 times for specifically the SatelliteVis layer/section into a comboBox for the user to select a time step from those 9 that I would read from the XML? I am writing in C# using Microsoft Visual C# 2010. I would really appreciate any help you can give me.

Posted 6-Aug-13 5:10am

Henry Hunt

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2 solutions

Solution 1

In .NET FCL, there are different XML parsers. This is my short overview of them:

Use System.Xml.XmlDocument class. It implements DOM interface; this way is the easiest and good enough if the size if the document is not too big.
See http://msdn.microsoft.com/en-us/library/system.xml.xmldocument.aspx[^].
Use the class System.Xml.XmlTextReader; this is the fastest way of reading, especially is you need to skip some data.
See http://msdn.microsoft.com/en-us/library/system.xml.xmlreader.aspx[^].
Use the class System.Xml.Linq.XDocument; this is the most adequate way similar to that of XmlDocument, supporting LINQ to XML Programming.
See http://msdn.microsoft.com/en-us/library/system.xml.xmldocument.aspx[^], http://msdn.microsoft.com/en-us/library/bb387063.aspx[^].

Enjoy,

—SA

Posted 6-Aug-13 5:44am

Sergey Alexandrovich Kryukov

Comments

ridoy 6-Aug-13 12:41pm

a plenty,+5 SA.

Sergey Alexandrovich Kryukov 6-Aug-13 12:42pm

Thank you very much,
—SA

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Tim Golisch · Accepted Answer · 2013-08-06T05:52:00

Solution 2

I prefer to use XPath to get the list of Time nodes.
Try this code:

C#

Xml.XmlNodeList xmlNodes;
Xml.XmlDocument xmlDoc = New Xml.XmlDocument();
xmlDoc.LoadXml(strXML); //strXML is a var that contains your xml (that you posted, above)

const string xpathQuery = "/Layers/Layer[@displayName='SatelliteVis']/Service/Times/Time";
xmlNodes = xmlDoc.SelectNodes(xpathQuery);

//iterate through the list of nodes and load your listbox
for (int x = 0; x < xmlNodes.Count; x++)
{
    listbox1.add(xmlNodes(x).InnerText);
}

Posted 6-Aug-13 5:52am

Tim Golisch

Updated 6-Aug-13 9:23am

v2

Comments

Henry Hunt 6-Aug-13 12:44pm

Thank you so much, it worked great after a few changes. One more thing, it returns the whole element (e.g: 'time 2013-08-06T15:00:00 /time' is there a way to just get the data inside the tags or would I just use replace to replace the 2 tags either side of the data with an empty space?

Tim Golisch 6-Aug-13 15:19pm

I changed the code (above) to use xmlNodes(x).InnerText instead of xmlNodes(x).OuterXml. That should be more useful for you.

Henry Hunt 7-Aug-13 6:53am

Another thing, how would I read an attribute and put it into a string for use in a URL? For example, how would I read the attribute value for 'displayName' in the SatelliteVis layer and store it in a string? Thanks.

Tim Golisch 7-Aug-13 8:24am

You can use this XPath query to get the list of displayName values:
"/Layers/Layer/@displayName"

Henry Hunt 8-Sep-13 12:08pm

Hello again, I have just one more thing for you. How would I reference to a specific 'set' of elements depending on on of the containing element values instead of the attribute at the top of the 'set' of elements. For example: The code I want to read is below. How would I get the Risk level from specifying the Area element?

How would I get the risk level for the Area value of East Highland? I don't want to use indexing, ie: using SelectNodes("")[n].innerText as the 'sets' of MountainForecast elements could be in a different order Thank you.

mountainforecastlist
mountainforecast
datadate/2013-09-08T04:04:39Z/datadate
validfrom/2013-09-08T04:00:00Z/validfrom
validto/2013-09-12T04:00:00Z/validto
createddate/2013-09-08T03:05:48Z/createddate
uri/http://datapoint.metoffice.gov.uk/public/data/txt/wxfcs/mountainarea/{format}/100?key={key}/uri
Area/Brecon Beacons/Area
risk/Medium/risk
mountainforecast
mountainforecast
datadate/2013-09-08T03:26:42Z/datadate
validfrom/2013-09-08T03:00:00Z/validfrom
validto/2013-09-12T03:00:00Z/validto
createddate/2013-09-08T02:26:48Z/createddate
uri/http://datapoint.metoffice.gov.uk/public/data/txt/wxfcs/mountainarea/{format}/101?key={key}/uri
Area/East Highland/Area
risk/Medium/risk
mountainforecast
mountainforecastlist

Had to remove the tag start and ends so hope you can read it, I put / between element and its value.

Tim Golisch 9-Sep-13 11:03am

This XPath should handle it:
/mountainforecastlist/mountainforecast[Area='East Highland']/risk