Question

I am learning LINQ and this seems like a fairly simple problem. I have a semi-working solution but I am sure it could be cleaned up.

The propertyAuto node represents a car with id = 606.
This node needs to have at least two child propertyValue nodes, one that references a vehicleValuation element with attribute of “Book” and one of “Auto”. (My code doesnt check this yet, they could both be Auto or Book now)

Finally, I need to get the Book value and Auto Value for the same car.

Note that I will never know any IDs or idRef’s beforehand and in the future there will be multiple cars.

Here is my code now (ready to copy into LINQPad!)

var data = XElement.Parse (@"
<MyXML>
  <propertyAuto id='606'>
    <Values>
      <propertyValue idRef='f95d5dce-8152-4e9e-889e-7433d32664d6' />
      <propertyValue idRef='cd1a83a7-dd04-41f9-b31c-5408a38ac777' />
    </Values>
  </propertyAuto>
  <Valuations>
    <vehicleValuation id='cd1a83a7-dd04-41f9-b31c-5408a38ac777'
    valuationType='Auto' estimatedValue='8350.00' />
    <vehicleValuation id='f95d5dce-8152-4e9e-889e-7433d32664d6'
    valuationType='Book' estimatedValue='12475.00' />
  </Valuations>
</MyXML>");

var valuations = from property in data.Descendants("propertyValue")
                 join value in data.Descendants("vehicleValuation")
                 on
                    (string)property.Attribute("idRef")
                 equals
                    (string)value.Attribute("id")
                 where property.Parent.Descendants("propertyValue").Count() > 1
                 && ((string)value.Attribute("valuationType") == "Auto" || (string)value.Attribute("valuationType") == "Book")               
                 select new { Value = value.Attribute("estimatedValue").Value, Type = value.Attribute("valuationType").Value, PropertyID = property.Parent.Parent.Attribute("id").Value };

valuations.Dump();

var values = valuations.GroupBy(x=> x.PropertyID).FirstOrDefault();
string auto = values.Where(x => x.Type == "Auto").Select(x=>x.Value).First().ToString();
string book = values.Where(x => x.Type == "Book").Select(x=>x.Value).First().ToString();

auto.Dump();
book.Dump();

Is this workable or should I move to xpath, etc?

Answer 1

Clearly your solution is workable because it works! I would also take it a little further to get the results as a list of cars with properties that you can easily inspect:

var carProperties = from propertyAuto in data.Descendants("propertyAuto")
                    select new
                    {
                        Id = propertyAuto.Attributes("id").First().Value,
                        Properties = from property in propertyAuto.Descendants("propertyValue")
                                     join value in data.Descendants("vehicleValuation")
                                     on property.Attribute("idRef").Value
                                     equals value.Attribute("id").Value
                                     select new
                                     {
                                         Value = value.Attribute("estimatedValue").Value,
                                         Type = value.Attribute("valuationType").Value,
                                         PropertyID = property.Parent.Parent.Attribute("id").Value
                                     }
                    };

var cars = from car in carProperties
           select new
           {
               Id = car.Id,
               Auto = car.Properties.Where(x => x.Type == "Auto").Select(x => x.Value).First(),
               Book = car.Properties.Where(x => x.Type == "Book").Select(x => x.Value).First()
           };

Notice that the GroupBy is no longer needed.