How to get the list of values from the Soap Response?

Question

I am hitting a web service method. This Web service method returns values in the XML format.

When I am trying to get this element. I am getting a single ElementName with the following code in debug mode.

    givenwsdl.periodictableSoap   proxyClass = new givenwsdl.periodictableSoap  ();
String retVal = proxyClass.GetAtoms();
String GetAtomicNumber = proxyClass.GetAtomicNumber('Nitrogen');
System.debug('retVal'+retVal);
System.debug('GetAtomicNumber'+GetAtomicNumber);
 conversionclass parser=new conversionclass(retVal);
for(integer i=0;i<(retVal.length());i++)
{
    String sName=getNodeValue(parser,'ElementName');
    System.debug('test'+sName);
}


 //To get Node value based on tag name from parser
    public String getNodeValue(conversionclass parser1,String tagName)
    {
        if(parser!=null && tagname!=null)
        {
            conversionclass.Element element=parser.getElementByTagName(tagName);
            if(element!=null)
                return element.nodeValue;
        }
        return '';
    }

    //To get Node value based on tag name from Element
    public String getNodeValue(conversionclass.Element parser1,String tagName)
    {
        if(parser!=null && tagname!=null)
        {
            conversionclass.Element element=parser.getElementByTagName(tagName);
            if(element!=null)
                return element.nodeValue;

        }
        return '';
    }    

Problem: How to get all atomic number in the single list, So that i can use it in Vf page to display it using <apex:data-list> or <apex:repeat>

Thanks in advance.

Answer 1

Although you do not link to it, I presume that the web service you are calling is http://www.webservicex.net/periodictable.asmx.

The string returned by the GetAtoms operation is itself XML with many ElementName elements:

<string xmlns="http://www.webserviceX.NET">
    <NewDataSet>
        <Table> <ElementName>Actinium</ElementName> </Table>
        <Table> <ElementName>Aluminium</ElementName> </Table>
        ...

(By the way this seems like a poor design choice to me as the structure being returned is not modelled in the WSDL and so has to be separately assumed/implemented.)

I suggest you use a DOM parser e.g.:

private String[] parseElementNames(String retVal) {

    String[] elements = new String[] {};

    Dom.Document doc = new Dom.Document();
    doc.load(retVal);
    Dom.XmlNode root = doc.getRootElement();
    Dom.XmlNode ds = root.getChildElement('NewDataSet', 'http://www.webserviceX.NET');

    for (Dom.XmlNode t : ds.getChildElements()) {
        Dom.XmlNode en = t.getChildElement('ElementName', 'http://www.webserviceX.NET');
        elements.add(en.getText());
    }

    return elements;
}

Once you have those names, you can loop over them and invoke the GetAtomicNumber operation on each. But as only 100 web service callouts are allowed per transaction in Apex you will not be able to do that for all of them.

Put the results in a public array array field of:

public class Item {
    public String elementName {get; set;}
    public Decimal atomicNumber {get; set;}
}

that you can then iterate over in your Visualforce.

PS

I don't know why your code is not working. Make sure that the XML coming from the service matches what I have listed above. This test passes:

@IsTest
private class MyTest {

    @IsTest
    static void test() {
        String xml = ''
                + '<string xmlns="http://www.webserviceX.NET"><NewDataSet>'
                + '<Table> <ElementName>Actinium</ElementName> </Table>'
                + '<Table> <ElementName>Aluminium</ElementName> </Table>'
                + '</NewDataSet></string>'
                ;
        System.assertEquals(new String[] {'Actinium', 'Aluminium'}, parseElementNames(xml));
    }

    private static String[] parseElementNames(String retVal) {

        String[] elements = new String[] {};

        Dom.Document doc = new Dom.Document();
        doc.load(retVal);
        Dom.XmlNode root = doc.getRootElement();
        Dom.XmlNode ds = root.getChildElement('NewDataSet', 'http://www.webserviceX.NET');

        for (Dom.XmlNode t : ds.getChildElements()) {
            Dom.XmlNode en = t.getChildElement('ElementName', 'http://www.webserviceX.NET');
            elements.add(en.getText());
        }

        return elements;
    }
}

This (from your comment) is definitely wrong:

Dom.XmlNode ds = root.getChildElement('NewDataSet', 'null');

If there is no namespace the second argument should be the literal null not the string 'null'.