Question

I have a call to a get action method with a list of query string parameters being passed to that method. A few of those parameters have a pipe ‘|’ in them. The problem is that I cannot have action method parameters with pipe characters in them. How do I map a piped querystring parameter to a non-piped C# parameter? Or is there some other trick that I don’t know about?

Answer 1

You could write a custom model binder. For example let’s suppose that you have the following request:

/foo/bar?foos=foo1|foo2|foo3&bar=baz

and you would like to bind this request to the following action:

public ActionResult SomeAction(string[] foos, string bar)
{
    ...
}

All you have to do is write a custom model binder:

public class PipeSeparatedValuesModelBinder : IModelBinder
{
    public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        var values = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        if (values == null)
        {
            return Enumerable.Empty<string>();
        }

        return values.AttemptedValue.Split('|');
    }
}

and then:

public ActionResult SomeAction(
    [ModelBinder(typeof(PipeSeparatedValuesModelBinder))] string[] foos, 
    string bar
)
{
    ...
}