Deserializing JSON object array to List

Question

I'm trying to read this JSON array:

[{"name":"lc_cash","slot":1,"info":"","type":"item","amount":591},{"name":"advancedlockpick","slot":2,"info":[],"type":"item","amount":19}]

This is my code:

File Inventory.cs

class Item {
    [JsonProperty("name")]
    public string Name { get; set; }

    [JsonProperty("slot")]
    public int Slot { get; set; }

    [JsonProperty("info")]
    public object Info { get; set; }

    [JsonProperty("type")]
    public string Type { get; set; }

    [JsonProperty("amount")]
    public int Amount { get; set; }
}

class Inventory
{
    public List<Item> Item { get; set; }
}

File Form1.cs

Inventory inventory = new Inventory();
inventory = JsonSerializer.Deserialize<Inventory>(players.Inventory);

I'm getting this error:

System.Text.Json.JsonException: 'The JSON value could not be converted to Inventory. Path: $ | LineNumber: 0 | BytePositionInLine: 1.'

How can I read this correctly?

EDIT: testing with stackoverflow answers:

Main code:

List<Item> items = new List<Item>();
items = JsonSerializer.Deserialize<List<Item>>(players.Inventory);

Item class:

class Item {
    [JsonProperty("name")]
    public string Name { get; set; }

    [JsonProperty("slot")]
    public int Slot { get; set; }

    [JsonProperty("info")]
    public string Info { get; set; }

    [JsonProperty("type")]
    public string Type { get; set; }

    [JsonProperty("amount")]
    public int Amount { get; set; }
}

Result: It's not throwing exception anymore but reading only 0 and nill

i don't think it knows how to convert `Info` being a `System.Object` — Daniel A. White, Jan 01 '22 at 14:43

score 0 · Answer 1 · answered Jan 01 '22 at 14:45

0

as long as the information here is right, you gave us a json array string. the inventory is an object with an array, so the simple solution will be this:

  Inventory inventory = new Inventory();
  inventory.Item = JsonSerializer.Deserialize<List<Item>>(players.Inventory);

important to mention that since Item is a list, you should use plural name

answered Jan 01 '22 at 14:45

Or Yaacov

3,597
5
25
49

now it's not throwing error but it reads only 0 and nill – Adrian Hernando Solanas Jan 01 '22 at 15:19

Serge · Accepted Answer · 2022-01-01T18:46:23.250

you will have to fix your json, one of the property info has value string, another has array. you have to select something one, null for example

var jsonParsed = JArray.Parse(json);

foreach (var item in jsonParsed)
{
    
        if (((JObject)item)["info"].GetType().Name == "JArray"
        || ((JObject)item)["info"].GetType().Name == "JValue")
            ((JObject)item)["info"] = null;
}

List<Item> items = jsonParsed.ToObject<List<Item>>();

result

[
  {
    "name": "lc_cash",
    "slot": 1,
    "info": null,
    "type": "item",
    "amount": 591
  },
  {
    "name": "advancedlockpick",
    "slot": 2,
    "info": null,
    "type": "item",
    "amount": 19
  }
]

UPDATE

if you sometimes have

"info":{"food":30,"thirst":30}

it is better to change info property to this

[JsonProperty("info")]
public Dictionary<string,int> Info { get; set; }

or a little more complicated

[JsonProperty("info")]
public Info Info { get; set; }

public class Info
{
[JsonProperty("food")]
  public int Food {get; set;}

[JsonProperty("thirst")]
public int Thirst {get; set;}
}

@AdrianHernandoSolanas But what info is wnen it is not empty? — Serge, Jan 01 '22 at 18:04
that's in the other question https://stackoverflow.com/questions/70550319/jsonserializer-deserialize-exception-the-json-value-could-not-be-converted-to-s/70550479?noredirect=1#comment124714055_70550479 — Adrian Hernando Solanas, Jan 01 '22 at 18:36

Deserializing JSON object array to List

2 Answers2