Passing int array as parameter in web user control

Question

I have an int array as a property of a Web User Control. I'd like to set that property inline if possible using the following syntax:

<uc1:mycontrol runat="server" myintarray="1,2,3" />

This will fail at runtime because it will be expecting an actual int array, but a string is being passed instead. I can make myintarray a string and parse it in the setter, but I was wondering if there was a more elegant solution.

Answer 1

You could also do something like this:

namespace InternalArray
{
    /// <summary>
    /// Item for setting value specifically
    /// </summary>

    public class ArrayItem
    {
        public int Value { get; set; }
    }

    public class CustomUserControl : UserControl
    {

        private List<int> Ints {get {return this.ItemsToList();}
        /// <summary>
        /// set our values explicitly
        /// </summary>
        [PersistenceMode(PersistenceMode.InnerProperty), TemplateContainer(typeof(List<ArrayItem>))]
        public List<ArrayItem> Values { get; set; }

        /// <summary>
        /// Converts our ArrayItem into a List<int> 
        /// </summary>
        /// <returns></returns>
        private List<int> ItemsToList()
        {
            return (from q in this.Values
                    select q.Value).ToList<int>();
        }
    }
}

which will result in:

<xx:CustomUserControl  runat="server">
  <Values>
            <xx:ArrayItem Value="1" />
  </Values>
</xx:CustomUserControl>

Answer 2

Implement a type converter, here is one, warning : quick&dirty, not for production use, etc :

public class IntArrayConverter : System.ComponentModel.TypeConverter
{
    public override bool CanConvertFrom(System.ComponentModel.ITypeDescriptorContext context, Type sourceType)
    {
        return sourceType == typeof(string);
    }
    public override object ConvertFrom(System.ComponentModel.ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
    {
        string val = value as string;
        string[] vals = val.Split(',');
        System.Collections.Generic.List<int> ints = new System.Collections.Generic.List<int>();
        foreach (string s in vals)
            ints.Add(Convert.ToInt32(s));
        return ints.ToArray();
    }
}

and tag the property of your control :

private int[] ints;
[TypeConverter(typeof(IntsConverter))]
public int[] Ints
{
    get { return this.ints; }
    set { this.ints = value; }
}

Answer 3

@mathieu, thanks so much for your code. I modified it somewhat in order to compile:

public class IntArrayConverter : System.ComponentModel.TypeConverter
{
    public override bool CanConvertFrom(System.ComponentModel.ITypeDescriptorContext context, Type sourceType)
    {
        return sourceType == typeof(string);
    }
    public override object ConvertFrom(System.ComponentModel.ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
    {
        string val = value as string;
        string[] vals = val.Split(',');
        System.Collections.Generic.List<int> ints = new System.Collections.Generic.List<int>();
        foreach (string s in vals)
            ints.Add(Convert.ToInt32(s));
        return ints.ToArray();
    }
}

Answer 4

You can implement a type converter class that converts between int array and string data types. Then decorate your int array property with the TypeConverterAttribute, specifying the class that you implemented. Visual Studio will then use your type converter for type conversions on your property.

Answer 5

Have you tried looking into Type Converters? This page looks worth a look: http://www.codeguru.com/columns/VB/article.php/c6529/

Also, Spring.Net seems to have a StringArrayConverter (http://www.springframework.net/doc-latest/reference/html/objects-misc.html - section 6.4) which, if you can feed it to ASP.net by decorating the property with a TypeConverter attribute, might work..

Answer 6

Seems to me that the logical—and more extensible—approach is to take a page from the asp: list controls:

<uc1:mycontrol runat="server">
    <uc1:myintparam>1</uc1:myintparam>
    <uc1:myintparam>2</uc1:myintparam>
    <uc1:myintparam>3</uc1:myintparam>
</uc1:mycontrol>