C# Parse JSON object array to List<T>

Question

I have a form that uses jquery $.post to send the following JSON to the server:

{
    id: 1,
    label: "myLabel",
    results: [
        { name: "myName1", value: "myValue1" },
        { name: "myName2", value: "myValue2" }
    ]
}

The JSON is posted to a controller similar to this:

public ActionResult Submit(int id, string label, List<object> results){...}

I also have the following class:

public class FormValue {
    public string name {get;set;}
    public string value {get;set;}
}

I'd like to be able to cast the contents of the JSON 'results' array to the 'FormValue' class in such a way that I could write the controller as:

public ActionResult Submit(int id, string label, List<FormValue> results){...}

What am I missing?

Also I assume that this is an MVC or Web API controller. You cant have a single json object be bound to multiple parameters. You have to have a single object (and therefor 1 method parameter) that represents the json. Alternatively you could send the other parts (id, label) using query string parameters and the results as the json objects in the http body. — Igor
– Igor, Commented Jan 11, 2017 at 17:46
Yes to MVC. I'm seeing examples where the json data to be sent uses JSON.stringify to pass it all as one string rather than the object, so $.post data to be sent would be: var dataToBeSent = { id: data.id, label: data.label, results: $('#form').serializeArray() }; — Ryan Dunphy
– Ryan Dunphy, Commented Jan 11, 2017 at 17:48
@RyanDunphy - correct but on the receiving end you have 1 c# object. So you would have something like public class Model{public string Id {get;set;} public string Label {get;set;} public List<FormValues> Results {get;set;}}. That type then becomes the single parameter in your action method. — Igor
– Igor, Commented Jan 11, 2017 at 17:51

Igor · Accepted Answer · 2017-01-11 17:54:12Z

2

On the receiving end you have 1 c# object. So you would have something like

public class Model { 
  public string Id {get;set;} 
  public string Label {get;set;} 
  public List<FormValues> Results {get;set;}
}

That type then becomes the single parameter in your action method.

[HttpPost] // do not forget this
public ActionResult Submit(Model model){/*...*/}

This is because the json object you are sending in the Http method body can only be mapped to a single corresponding c# object (if you are using the built in binding).

Also note the restriction on the Http verb. You could also use HttpPut if the action is considered idempotent. This can never be a HttpGet method as Http get does not support a message body.

answered Jan 11, 2017 at 17:54

Igor

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