Parse complex JSON data in ActionFilter

Question

I used to have an action processing some complex JSON data:

[HttpPost, ValidateAntiForgeryToken]
public ActionResult GetAdditionals(string pageIdentifier,
    IEnumerable<HtmlPlaceHolder> htmlPlaceHolders,
    IEnumerable<DataSource> dataSourceRequests)

that was called from client side like this:

var requestData = {
    pageIdentifier: 'test',
    htmlPlaceHolders: getHtmlPlaceHolders(),
    dataSourceRequests: getDataSourceRequests(),
    __RequestVerificationToken: token
};
$.post(url, $.toDictionary(requestData), resultHandler, "json");

Where htmlPlaceHolders and dataSourceRequests would contain arrays of objects matching the classes shown in the signature of the action method.

$.toDictionary() is used to get the complex object to the server in a proper manner.

That was all working fine. But now I want to do some processing of the same post data in an ActionFilter. Therefore, in the OnActionExecuting methode, I want to parse the data in the NameValueCollection contained in filterContext.HttpContext.Request.Form where the names of the name/value pairs look like:

pageIdentifier
htmlPlaceHolders[0].ControlId
htmlPlaceHolders[0].FunctionName
htmlPlaceHolders[0].Parameter
...
...
dataSourceRequests[0].Id
dataSourceRequests[0].Src

Now I need to know how I can reconstruct the IEnumerable<HtmlPlaceHolder> and IEnumerable<DataSource> from this NameValueCollection like the default model binder did for my action. So far, I cannot figure out a nice way to accomplish this.

Sam FarajpourGhamari · Accepted Answer · 2015-08-19 18:35:13Z

1

For this kind of scenarios it is better to use model binder instead of action filter. Consider this as an simple example:

public class MyComplexBinder : IModelBinder
{
    public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        // check type of the object you are going to bind with 
        // bindingContext.ModelType
        // if you could generate this kind of object use
        // controllerContext.HttpContext.Request.Form
        // or anything else and return generated object
        return GenerateMyComplexObject(controllerContext); 
    }
}

Then you could use this binder like this:

public string MyAction([ModelBinder(typeof(MyComplexBinder))]MyComplexType complexParameter)
{
}

If you think this looks ugly write your custom model binder attribute:

public class ComplexAttribute : CustomModelBinderAttribute
{
    public override IModelBinder GetBinder()
    {
        return new MyComplexBinder();
    }
}

Then you could write:

public string MyAction([Complex]MyComplexType complexParameter)
{
}

You could also register your model binder as a global binder in Global.asax.cs:

protected void Application_Start()
{
    // some codes here

    ModelBinders.Binders.Add(typeof(MyComplexType),new MyComplexBinder());
}

answered Aug 19, 2015 at 18:35

Sam FarajpourGhamari

14.8k4 gold badges57 silver badges56 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Moolie Over a year ago

Thanks for your elaborate reply Sam, but the purpose of moving the functionality from an action to an actionfilter was to remove the action. The whole context: GetAdditionals was called after almost every ajax post to get additional info from the server that wasn't provided in the original answer from the server. A very silly solution. Now the model changes plus the extra stuff from GetAdditionals are sent in the same ajax call. I standardized the whole process, but I don't want the signature of every action cluttered with the parameters that were in GetAdditionals, thus the ActionFilter.

Moolie Over a year ago

BTW, I now created a c# class that holds all the parameters of the GetAdditionals call, use JSON.stringify to send the object to the server and reconstruct an object of that class using JsonConvert.DeserializeObject<MyClass>()

Collectives™ on Stack Overflow

Parse complex JSON data in ActionFilter

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related