CODEWITHSUNDEEP
c#linq
user9993
user9993

Reputation: 6170

LINQ to Objects - Initialising lists

How do I use LINQ to create an object and also initialise list's within that object? (Also, I'm trying to create an immutable object.) I'm accessing an XML web service.

For example, I have a class with several properties. However, I also have some private lists within the class.

public class MyClass
{
    public string SomeProperty { get; private set; }
    public string AnotherProperty { get; private set; }

    internal List<Result> ResultSet1 { get; set; }
    internal List<Result> ResultSet2 { get; set; }

    public IEnumerable<Result> GetResultSet1()
    {
        return ResultSet1;
    }

    //Constructor here to set the private properties eg: this.SomeProperty = someProperty;

    //etc.
}

And then I have Result.cs:

public class Result
{
    public string YetAnotherProperty { get; private set; }
    //etc.
}

So far I am able to using LINQ to read the XML and create a "MyClass" object and then set it's properties via the constructor. However, I do not know how to either:

This is the LINQ I have so far:

//Use the contents of XML nodes/elements as the arguments for the constructor:
var query = from i in document.Descendants("response")
                           select new MyClass
                           (
                               (string)i.Element("some").Element("property"),
                               (string)i.Element("another").Element("property")
                           )

My question: I don't know enough about LINQ or creating objects with LINQ to know how to initialise lists within an object I am trying to create. How do I go about doing this? How do I add items to ResultSet1 from the LINQ?

Upvotes: 1

Views: 1289

Answers (2)

Jonesopolis
Jonesopolis

Reputation: 25370

just add the object initializer after calling your constructor:

var query = from i in document.Descendants("response")
                       select new MyClass
                       (
                           (string)i.Element("some").Element("property"),
                           (string)i.Element("another").Element("property")
                       )
                       {
                           ResultSet1 = new List<Result>
                                  {
                                      new Result { YetAnotherProperty = ... },
                                      new Result { ... }            
                                  },
                           ResultSet 2 = ...
                       };

although this gets pretty nasty, and could make it hard to debug down the road. What about a constructor that took the node and parsed it out?

Upvotes: 1

Jeff Mercado
Jeff Mercado

Reputation: 134491

Assuming the properties are accessible, you can simply set the properties through the regular object initializer syntax. Just add a pair of braces after your new call and set the properties.

var query =
    from response in document.Descendants("response")
    // for readability
    let someProperty = (string)response.Element("some").Element("property")
    let anotherProperty = (string)response.Element("another").Element("property")
    select new MyClass(someProperty, anotherProperty)
    {
        ResultSet1 = response.Elements("someSet")
            .Select(ss => new Result
            {
                YetAnotherProperty = (string)ss.Element("another")
                                               .Element("property")
            })
            .ToList()
        ResultSet2 = /* etc. */,
    };

Upvotes: 3

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