MVC passing post parameter to a dictionary

Question

I have MVC application that returns a ResultObjekt after processing a FormulaData object. That's a rest API called via HTTP-Post

[HttpPost]
[ActionName("GetResult")]
public ResultObjekt GetResult([FromBody]FormularData values)
{

}

Question: Is there a way to read all properties from values into a Dictionary<string, string> or a IEnumerable<KeyValuePair<string, string>> ?

e.g.

public class FormularData
{
    public string Item1 { get; set; }
    public string Item2 { get; set; }
}

should result into a Dictionary<string,string>() or a IEnumerable<KeyValuePair<string, string>>

with values { {"Item1","Value1"}, {"Item2","Value2"}}

My previous solution worked with Querystring and HttpGet instead of HttpPost and since I changed, Request.GetQueryNameValuePairs().ToDictionary(x => x.Key, x => x.Value) doesn't work anymore.

---

Here is my current - not so pretty solution:

[HttpPost]
[ActionName("GetResult")]
public ResultObjekt GetResult([FromBody]FormularData values)
{
    List<KeyValuePair<string, string>> list = new List<KeyValuePair<string, string>>();
    if (!string.IsNullOrEmpty(values.Item1))
    {
        list.Add(new KeyValuePair<string, string>("Item1", values.Item1));
    }
    if (!string.IsNullOrEmpty(values.Item2))
    {
        list.Add(new KeyValuePair<string, string>("Item2", values.Item2));
    }
    IEnumerable<KeyValuePair<string, string>> result = list.AsEnumerable();
}

Answer 1

As already mentioned by many in the comments that ideally one should use a model that can hold the values from the form. This is also the cleanest way as per my opinion, as I find it more structured.

If you need to access both at the same time, first try to refactor/restructure the code if possible. In my opinion why try to access the raw form data when that is already bound to our model, considering the form data is a subset of the model data.

If refactoring/restructuring is not possible, and you need to access both, then there are couple of ways to do that.

1. Option1: Use FormCollection:

   [HttpPost]
   public ResultObjekt GetResult(FormCollection formCol, FormularData model)
   {
       //Note that here both FormCollection and FormularData are used.
       //To get values from FormCollection use something like below:
       var item1 = formCol.Get("Item1");
   }
   

2. Option2: Use Request.Form:

   [HttpPost]
   public ResultObjekt GetResult(FormularData model)
   {
       //To get values from Form use something like below:
       var formData = Request.Form;
       var item1 = formData.Get("Item1");
   }
   

Hope this helps.

Update: As also pointed out by Lali, whether you use FormCollection or Request.Form, you can convert that into dictionary as: formData.AllKeys.ToDictionary(k => k, v => formData[v]) (untested), as both are of type NameValueCollection

Answer 2

While using reflection may have a performance hit you can convert the model to a dictionary using linq with reflection.

[HttpPost]
[ActionName("GetResult")]
public ResultObjekt GetResult([FromBody]FormularData values)
{
    var result = values.GetType()
                     .GetProperties()
                     .ToDictionary(pi => pi.Name, pi => (string)pi.GetValue(values));
}

performance can be improved by caching the property info returned from GetProperties. The above linq can also be converted to an extension method for reuse if desired.

Answer 3

I think you are making your life difficult for no reason.
If you need to treat your class as a dictionary just implement an implicit operator like in the following example

If you just want to iterate on the object,you can just implement IEnumerable

using System;
using System.Collections;
using System.Collections.Generic;

namespace ConsoleApplication5
{
    class Program
    {

        static void Main(string[] args)
        {
            FormularData data = new FormularData() { Item1 = "aa", Item2 = "bb" };
            //Dictionary<string, string> dictionary = data;
            foreach (var item in data)
                Console.WriteLine(item);

            Console.ReadLine();
        }
    }

    public class FormularData : IEnumerable<KeyValuePair<string,string>>
    {
        public string Item1 { get; set; }
        public string Item2 { get; set; }

        public static implicit operator Dictionary<string, string>(FormularData obj)
        {
            var list = new Dictionary<string, string>();
            if (!string.IsNullOrEmpty(obj.Item1))
                list.Add("Item1", obj.Item1);
            if (!string.IsNullOrEmpty(obj.Item2))
                list.Add("Item2", obj.Item2);
            return list;
        }

        public IEnumerator<KeyValuePair<string, string>> GetEnumerator()
        {
            return ((Dictionary<string, string>)this).GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return this.GetEnumerator();
        }
    }
}

Answer 4

The power of Extension methods can be used out here.

1. Define an extension for FormularData class:

            public static class FormularDataExtensions
            {
               public static Dictionary<string, string> ConvertToDictionary(this FormularData formularData)
               {
                 var dictionary = new Dictionary<string, string>();
                 if (!string.IsNullOrEmpty(formularData.Item1))
                     dictionary.Add(nameof(formularData.Item1), formularData.Item1);
                 if (!string.IsNullOrEmpty(formularData.Item2))
                     dictionary.Add(nameof(formularData.Item2), formularData.Item2);
   
                return dictionary;
               }
            }
   

2. Call ConvertToDictionary() in GetResult() as:

   [HttpPost]
   [ActionName("GetResult")]
   public ResultObjekt GetResult([FromBody]FormularData values)
   {
       var dictionary = values.ConvertToDictionary();
   }