Bind a complex class on MVC asp.net

Question

I have the following classes:

public class Movie
{
 string Name get; set;
 string Director get;  set;
 IList<Tag> Tags get; set;
}

public class Tag
{
    string TagName get; set;
}

On the Action of my controller I bind like this: public ActionResult Create([ModelBinder(typeof(MovieBinder))]Movie mo)

on theMovieBinder I convert the string to List<tag>. That when I debug works.

on the Movie binder I have the following code:

if (propertyDescriptor.Name == "Tags")
        {
            var values = bindingContext.ValueProvider.GetValue(propertyDescriptor.Name);
            if (values != null)
            {
                var p = values.AttemptedValue.Replace(" ", "");
                var arrayValues = p.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
                var list = new List<Tag>();
                foreach (string item  in arrayValues)
                {
                    list.Add(new Tag() { TagName = item });  
                }
                value = list;
            }
        }

But I get the following Error in the modelstate: Exception = {"The parameter conversion from type 'System.String' to type 'Models.Tag' failed because no type converter can convert between these types."}

I create a Tag binder, but it does not work, any ideas? Thanks!

What happened with this answer: stackoverflow.com/questions/6102850/… Didn't this work for you? — Darin Dimitrov
– Darin Dimitrov, Commented May 27, 2011 at 15:59
yes! Thanks! but Now I have this case.... where I create the Class Tag — elranu
– elranu, Commented May 27, 2011 at 16:08

Community · Accepted Answer · 2017-05-23 11:55:37Z

1

You could adapt the model binder I suggested here to this new situation where you have introduced the Tag class:

public class MovieModelBinder : DefaultModelBinder
{
    protected override object GetPropertyValue(ControllerContext controllerContext, ModelBindingContext bindingContext, System.ComponentModel.PropertyDescriptor propertyDescriptor, IModelBinder propertyBinder)
    {
        if (propertyDescriptor.Name == "Tags")
        {
            var values = bindingContext.ValueProvider.GetValue(propertyDescriptor.Name);
            if (values != null)
            {
                return values.AttemptedValue.Split(',').Select(x => new Tag
                {
                    TagName = x
                }).ToList();
            }
        }
        return base.GetPropertyValue(controllerContext, bindingContext, propertyDescriptor, propertyBinder);
    }
}

edited May 23, 2017 at 11:55

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answered May 27, 2011 at 16:12

Darin Dimitrov

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3 Comments

elranu Over a year ago

I did that! but I get the error. When I debug it works. And even I see the Movie object and has correctly fill the properties. But when I do ModelState.isValid I get false. I will edit my code, in the question.

Darin Dimitrov Over a year ago

@elranu, yes indeed there is an issue. I've updated my answer to fix it. It works if you override the GetPropertyValue method in the model binder instead of SetProperty.

elranu Over a year ago

can you see this question: stackoverflow.com/questions/6240209/bind-on-edit-asp-net-mvc Thanks

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