Question

Lets assume a xml file named data.xml with following content:

<root>
<record>
<id>1</id>
<name>test 1</name>
<resume>this is the resume</resume>
<specs>these are the specs</specs>
</record>
<record>
<id>2</id>
<name>test 2</name>
<resume>this is the resume 2</resume>
</record>
<record>
<id>3</id>
<name>test 3</name>
<specs>these are the specs 3</specs>
</record>
</root>

I need to search all records where any of these fields (id, name, resume or specs) contains a given value. I’ve created this code

XDocument DOC = XDocument.Load("data.xml");
IEnumerable<ProductRecord> results = from obj in DOC.Descendants("record")
     where 
obj.Element("id").Value.Contains(valueToSearch) ||
obj.Element("name").Value.Contains(valueToSearch) ||
obj.Element("resume").Value.Contains(valueToSearch) ||
obj.Element("specs").Value.Contains(valueToSearch)
     select new ProductRecord {
ID = obj.Element("id").Value,
Name = obj.Element("name").Value,
Resume = obj.Element("resume").Value,
Specs = obj.Element("specs").Value
     };

This code throws an error of NullReference since not all records have all fields.
How can i test if current record has a given element before i define a condition to apply? Ex. Record[@ID=3] has no resume.

Thanks in advance

Answer 1

You can write an extension method which is like bellow:

public static class XMLExtension
{
    public static string GetValue(this XElement input)
    {
        if (input != null)
            return input.Value;
        return null;
    }

    public static bool XMLContains(this string input, string value)
    {
        if (string.IsNullOrEmpty(input))
            return false;
        return input.Contains(value);
    }
}

and use it as below:

IEnumerable<ProductRecord> results = from obj in DOC.Descendants("record")
                                                 where
                                            obj.Element("id").GetValue().XMLContains(valueToSearch) || ...