How to use DataType.Custom in ASP.NET MVC 2?

Question

Can anyone tell me how to use DataType.Custom in ASP.NET MVC 2?

Answer 1

I haven't used it personally, but looking at the MSDN it seems to just be a matter of setting DataType = DataType.Custom and CustomDataType = "String". Then when you process your model you would check for DataType.Custom and if found perform different operations based on the value in CustomDataType.

Here's the sample they give on the MSDN:

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml.Linq;
using System.Web.DynamicData;
using System.ComponentModel.DataAnnotations;

public partial class TextField : System.Web.DynamicData.FieldTemplateUserControl {

    string getNavUrl() {

        var metadata = MetadataAttributes.OfType<DataTypeAttribute>().FirstOrDefault();
        if (metadata == null)
            return FieldValueString; 

        switch (metadata.DataType) {

            case DataType.Url:
                string url = FieldValueString;
                if (url.StartsWith("http://", StringComparison.OrdinalIgnoreCase) ||
                    url.StartsWith("https://", StringComparison.OrdinalIgnoreCase))
                    return url;

                return "http://" + FieldValueString;


            case DataType.EmailAddress:
                return "mailto:" + FieldValueString;

            default:
                throw new Exception("Unknown DataType");
        }
    }

    protected override void OnDataBinding(EventArgs e) {
        base.OnDataBinding(e);

        if (string.IsNullOrEmpty(FieldValueString))
            return;

        var metadata = MetadataAttributes.OfType<DataTypeAttribute>().FirstOrDefault();

        if (metadata == null || string.IsNullOrEmpty(FieldValueString)) {
            Literal literal = new Literal();
            literal.Text = FieldValueString;
            Controls.Add(literal);
            return;
        }

        if (metadata.DataType == DataType.Url ||
            metadata.DataType == DataType.EmailAddress) {

            HyperLink hyperlink = new HyperLink();
            hyperlink.Text = FieldValueString;
            hyperlink.NavigateUrl = getNavUrl();
            hyperlink.Target = "_blank";
            Controls.Add(hyperlink);
            return;
        }

        if (metadata.DataType == DataType.Custom &&
           string.Compare(metadata.CustomDataType, "BoldRed", true) == 0) {
            Label lbl = new Label();
            lbl.Text = FieldValueString;
            lbl.Font.Bold = true;
            lbl.ForeColor = System.Drawing.Color.Red;
            Controls.Add(lbl);
        }

    }

}

Source: http://msdn.microsoft.com/en-us/library/cc668199.aspx

Answer 2

I'd read over Brad Wilson's ASP.NET MVC 2 Template series on his blog here. It explains what you're asking better than I could.

Hope that helps.