开发者

How to data bind Entity Framework objects to a FormView

I am data binding to开发者_运维问答 many FormView controls using EF entity instances, but I have to resort to this ridiculous kludge in order to achieve what I want without using EntityDataSource controls:

propertyHeaderSection.DataSource = new List<PropertyDetailsModel> { _propertyDetails };

I suspect I will have to derive my own control from FormView and enable it to accept an almost POCO as a data source. Where do I start?


This is my implementation, sort of the same idea as patmortech, but i also found out that the ValidateDataSource method on the BaseDataBoundControl is what throws the exception at run-time if your datasource isn't enumerable.

public class CustomFormView : System.Web.UI.WebControls.FormView
    {
        public override object DataSource
        {
            get
            {
                if (!(base.DataSource is IEnumerable))
                    return new[] {base.DataSource};

                return base.DataSource;
            }
            set
            {
                base.DataSource = value;
            }
        }

        // This method complains at run time, if the datasource is not 
        // IListSource, IDataSource or IEnumerbale
        protected override void ValidateDataSource(object dataSource)
        {
            //base.ValidateDataSource(dataSource);
        }
    }

EDIT:

Considering the suggestion, i've made some changes to the way i check if the assigned DataSource is enumerable or not. I have also managed to create a sample app (VS 2010 Solution) to demo the changes. The app can be downloaded from http://raghurana.com/blog/wp-content/attachments/FormViewDataProblem.zip

In short this is what i am checking to ensure that the existing datasource can be enumerated already or not:

public static bool CanEnumerate( this object obj )
    {
        if (obj == null) return false;

        Type t = obj.GetType();

        return t.IsArray ||
               t.Implements(typeof (IEnumerable).FullName) ||
               t.Implements(typeof (IListSource).FullName) ||
               t.Implements(typeof (IDataSource).FullName);
    }

Please feel free to suggest more changes, if this isnt quite the desired functionality. Cheers.


Not sure it's the best idea in the world, but this is how you could derive from FormView to allow single object data source values. It basically does the same check that the ValidateDataSource does internally, and then creates a list wrapper for the item if it's not already a valid type.

public class SingleObjectFormView : System.Web.UI.WebControls.FormView
{
        public override object DataSource
        {
            get
            {
                return base.DataSource;
            }
            set
            {
                //will check if it's an expected list type, and if not, 
                //will put it into a list

                if (! (value == null || value is System.Collections.IEnumerable || value is System.ComponentModel.IListSource || value is System.Web.UI.IDataSource) )
                {
                    value = new List<object> { value };
                }

                base.DataSource = value;
            }
        }
 }
0

上一篇:

下一篇:

精彩评论

暂无评论...
验证码 换一张
取 消

最新问答

问答排行榜