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Using Linq, how to parse Xml objects in C # that only accept parameters in the constructor?

Suppose I have XML. For instance:

<User>
    <Name>X</Name>
    <Gender>Y</Gender>
    <ImageUrl>Z</ImageUrl>
</User>

and I have a class called User.

public class User
{
    public User(string name, string gender, string imageUrl) 
    {
        Name = name;
        Gender = gender;
        ImageUrl = imageUrl;
    }
    public string Name { get; }
    public string Gender { get; }
    public string ImageUrl { get; }
}

which only accepts the constructor public User(string name, string gender, string ImageUrl)and does not allow setting for properties, what is the best way to parse this xml in these objects using linq and C #?

In a rough manner, you can create anonymous objects, and then iterate over them to create the necessary objects. Is there a more efficient way to do this?

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2 answers

. LINQ to XML, XML User, , XML node:

// xml contains XML string, like in your sample
var document = XDocument.Parse(xml);
var users = document.Descendants("User")
   .Select(u => new User(
       u.Element("Name").Value,
       u.Element("Gender").Value, 
       u.Element("ImageUrl").Value
   ));
+5

, , .

, , , jimmy_keen, . "", , - , :

:

    ConstructorInfo GetBestConstructor(XElement elm, Type itemType)
    {
        var elements = elm.Elements();

        // Get a constructor with the most parameters that
        // are provided by xml elements.
        var ctor = (
            from c in itemType.GetConstructors()
            let p = c.GetParameters()
            where
                p.Length > 0 &&
                p.Count(parm => elements.Any(e => e.Name.LocalName.Equals(parm.Name, StringComparison.InvariantCultureIgnoreCase))) == p.Length
            select c
        )
            // Put the constructor with the most matching parameters
            // at the top of the list
        .OrderByDescending(c => c.GetParameters().Length)
        .FirstOrDefault();

        return ctor;
    }

    TType Construct<TType>(XElement elm)
    {
        var ctor = GetBestConstructor(elm, typeof(TType));
        if (ctor != null)
        {
            // We found a valid contructor!
            List<object> parameters = new List<object>();

            // Build a list of parameters, deserializing as we go.
            foreach (var p in ctor.GetParameters())
            {
                var item = elm.Elements().FirstOrDefault(e => e.Name.LocalName.Equals(p.Name, StringComparison.InvariantCultureIgnoreCase));
                if (item != null)
                {
                    TypeConverter converter = TypeDescriptor.GetConverter(p.ParameterType);
                    if (converter != null &&
                        converter.CanConvertFrom(typeof(string)))
                    {
                        // Deserialize each parameter and add it.
                        var parameter = converter.ConvertFrom(item.Value);
                        parameters.Add(parameter);
                    }
                }
            }

            // Create the object, using each parameter we've deserialized
            // to pass to the constructor.
            return (TType)ctor.Invoke(parameters.ToArray());
        }
        return default(TType);
    }

    public class User
    {
        public User(string name, string gender, string imageUrl)
        {
            Name = name;
            Gender = gender;
            ImageUrl = imageUrl;
        }
        public string Name { get; protected set; }
        public string Gender { get; protected set; }
        public string ImageUrl { get; protected set; }
    }

    public IEnumerable<User> GetUsers()
    {
        XDocument doc = XDocument.Parse(@"
<User>
    <Name>X</Name>
    <Gender>Y</Gender>
    <ImageUrl>Z</ImageUrl>
</User>");

        return doc
            .Descendants("User")
            .Select(u => Construct<User>(u));
    }

    static public void Main()
    {
        var p = new Program();
        var users = p.GetUsers().ToArray();
    }

, , , , .

-Doug

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