CODEWITHSUNDEEP
c#jsonjson.net
Aximili
Aximili

Reputation: 29444

Find a specific element anywhere in an arbitrary JSON

I am new to JSON.NET and not sure how to do this.

I have the CartItem class, and I need to implement
GetAllCartItemsFromArbitraryJson(string jsonStr), as follows:

class CartItem {
  public int Id;
  public int Qty;
}

List<CartItem> items = GetAllCartItemsFromArbitraryJson(jsonStr);

All I know is jsonStr contains one or more cartitems somewhere (I don't know how deep), eg.

{
  ... : {
    "cartitems": [{
        "id": "1",
        "qty": "1"
      },{
        "id": "2",
        "qty": "5"
      }
    ]
  },
  ... : {
    ... : {
      ...,
      "cartitems": [{
          "id": "10",
          "qty": "2"
        }
      ]
    }
  }
}

This function needs to collect all the cartitems and put it in List<CartItem>

List<CartItem> GetAllCartItemsFromArbitraryJson(string jsonStr) {
  JObject json = JObject.Parse(jsonStr);
  // then what...?
}

So the List<CartItem> will contains:

Id  Qty
1   1
2   5
10  2

How would you do it in C#?

Upvotes: 1

Views: 1283

Answers (2)

Aximili
Aximili

Reputation: 29444

This is a solution that works:

List<CartItem> GetAllCartItemsFromArbitraryJson(string jsonStr) {
  JObject json = JObject.Parse(jsonStr);

  return json.Descendants().OfType<JProperty>()  // so we can filter by p.Name below
             .Where(p => p.Name == "cartitems")
             .SelectMany(p => p.Value)           // selecting the combined array (joined into a single array)
             .Select(item => new CartItem {
                 Id  = (int)item["id"],
                 Qty = (int)item["qty"]
             }).ToList();
}

Hope it helps someone.
I am new to JSON though, got that by trial & error. So let me know if it can be improved :)

Upvotes: 4

Brian from state farm
Brian from state farm

Reputation: 2896

Parse to dynamic and iterate through the items.

public List<CartItem> PostAllCartItemsFromArbitraryJson(string jsonStr)
{
    List<CartItem> AllCartItems = new List<CartItem>();
    try
    {
        dynamic BaseJson = JObject.Parse(jsonStr.ToLower());

        CheckForCarts(AllCartItems, BaseJson);
    }
    catch (Exception Error)
    {
    }

    return AllCartItems;
}

private void CheckForCarts(List<CartItem> AllCartItems, dynamic BaseJson)
{
    foreach (dynamic InnerJson in BaseJson)
    {
        if (InnerJson.Name == "cartitems")
        {//Assuming this is an [] of cart items
            foreach (dynamic NextCart in InnerJson.Value)
            {
                try
                {
                    CartItem FoundCart = new CartItem();
                    FoundCart.Id = NextCart.id;
                    FoundCart.Qty = NextCart.qty;
                    AllCartItems.Add(FoundCart);
                }
                catch (Exception Error)
                {
                }
            }
        }
        else if (InnerJson.Value is JObject)
        {
            CheckForCarts(AllCartItems, InnerJson.Value);
        }
    }
}

public class CartItem
{
    public int Id;
    public int Qty;
}

For your sample input this generates:

[{"Id":1,"Qty":1},{"Id":2,"Qty":5},{"Id":10,"Qty":2}]

Upvotes: 1

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