CODEWITHSUNDEEP
asp.netasp.net-mvc
Risord
Risord

Reputation: 2196

How to require parameters in asp.net actions

How to require/validate parameters for actions. Right now I have lot of actions that looks like this (which is horrible):

public ActionResult DoSomething(string paramA, string paramB, string paramC)
{
    if (string.IsNullOrWhiteSpace(paramA))
    {
        return JsonResult(false, "paramA is missing");
    }

    if (string.IsNullOrWhiteSpace(paramB))
    {
        return JsonResult(false, "paramB is missing");
    }

    if (string.IsNullOrWhiteSpace(paramC))
    {
        return JsonResult(false, "paramC is missing");
    }

    //Actual Code
}

How to encapsulte this (potentially "globally")? I know that its possible to wrap parameters to model and use ModelState.IsValid like in this post: https://stackoverflow.com/a/39538103/766304 That is maybe one step forward on same places but generally I don't that it's realistic to wrap all parameters to models everywhere (~1 class definition per 1 action method... how nice is that?).

Also this is again per action ceremony which should be handled somewhere centralized:

if (ModelState.IsValid == false)
{
    return BadRequest(ModelState);
}

Upvotes: 1

Views: 347

Answers (2)

Łukasz Trzewik
Łukasz Trzewik

Reputation: 1165

The easiest way to do it would be to create a model class and use [Required] attributes like this:

public class FooModel 
{
   [Required]
   public string ParamA {get;set;}
   [Required]
   public string ParamB {get;set;}
   [Required]
   public string ParamC {get;set;}
}

And then use it in your controller like this:

public ActionResult DoSomething(FooModel model)
{
    if (!ModelState.IsValid)
    {
        // return some errors based on ModelState
    }

    //Actual Code
}

If you are looking for more global approach, then i believe you could look into Action Filters and use OnActionExecuting filter and handle the validation there (haven't used that myself tho). Here is how to do it: How can I centralize modelstate validation in asp.net mvc using action filters? That way your method would never be called if any of the parameters were missing.

Upvotes: 4

Haitham Shaddad
Haitham Shaddad

Reputation: 4456

The model annotations with [Required] [Length] and all these attributes is one of the most common ways to validate your model, specially it integrates with the Razor View engine and generates JavaScript validation as well, the same will happen if you are using EntityFramework for your back end, so this way you will have validation at the level of the UI, Controller and Data access.

You can also use Code Contracts which allows you to put pre and post conditions for your method in a nice way https://msdn.microsoft.com/en-us/library/dd264808(v=vs.110).aspx

If none of the above is still not enough, then you can add some checks in either your controller action or in your business domain service to make some business validation and return an error code if any errors found

Upvotes: 0

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