ServiceStack ormlite json不会从数据库反序列化

Question

ServiceStack ORMLite does not deserialize my class from Postgresql.

Keeping the objects on cache solves, but it can't load them back (saving is ok).

Below is a code that reproduces the problem.

void Main()
{
    var inv = new Inventory();
    inv.Items.Add(new Item{Id=1,CreatedAt=DateTime.Now, Key="potion10", Descriptions=new Dictionary<int, string>{{1,"Poção que recupera um pouco de vida."},{2,"Potion that restores a little of health."}}, HealthModifier=10,IsUseable=true, Names=new Dictionary<int, string>{{1,"Poção Leve"},{2,"Minor Potion"}}, UpdatedAt=DateTime.Now}, 2);

    var invJson = inv.ToJson().To<Inventory>(); // can't deserialize
    var invJsv = inv.ToJsv().To<Inventory>(); // same problem
}

public class Item
{
    public Item()
    {
        Names = new Dictionary<int, string>();
        Descriptions = new Dictionary<int, string>();
    }

    public long Id { get; set; }

    public string Key { get; set; }

    public Dictionary<int, string> Names { get; set; }

    public Dictionary<int, string> Descriptions { get; set; }

    public int HealthModifier { get; set; }

    public bool IsUseable { get; set; }

    public DateTime CreatedAt { get; set; }

    public DateTime UpdatedAt { get; set; }
}

public class Inventory
{
    public Inventory()
    {
        Items = new Dictionary<Item, int>();
    }

    public Dictionary<Item, int> Items { get; set; }
}

The JSON on Postgresql is the same from the code above.

{
    "Items":{
        "{"Id":1,
        "Key":"potion10",
        "Names":{
            "1":"Poção Leve",
            "2":"Minor Potion"
        },
        "Descriptions":{
            "1":"Poção que recupera um pouco de vida.",
            "2":"Potion that restores a little of health."
        },
        "HealthModifier":10,
        "IsUseable":true,
        "CreatedAt":"\/Date(1430743156138-0300)\/",
        "UpdatedAt":"\/Date(1430743156139-0300)\/"
    }:2
}
}

Answer 1

The problem is that your class Inventory has a dictionary keyed by a complex class:

public Dictionary<Item, int> Items { get; set; }

However, according to the ServiceStack.Text documentation

Any IDictionary is serialized into a standard JSON object, ie:

  {"A":1,"B":2,"C":3,"D":4} 

Unfortunately your Item class cannot be represented as a simple string thus cannot be used as a JSON property name .

What you could do is to serialize your items as an array of key-value pairs. Since the ServiceStack Text serializers support [DataMember] aliases and also support ignoring of data members , you can do the following:

[DataContract]
public class Inventory
{
    public Inventory()
    {
        Items = new Dictionary<Item, int>();
    }

    [IgnoreDataMember]
    public Dictionary<Item, int> Items { get; set; }

    [DataMember(Name = "Items")]
    public KeyValuePair<Item, int> [] ItemArray
    {
        get
        {
            return Items == null ? null : Items.ToArray();
        }
        set
        {
            (Items ?? (Items = new Dictionary<Item, int>())).Clear();
            if (value != null)
                foreach (var pair in value)
                    Items[pair.Key] = pair.Value;
        }
    }
}

This will serialize and deserialize valid JSON that should look something like this:

 { "Items": [ { "Key": { "Id": 1, "Key": "potion10", "Names": { "1": "Poção Leve", "2": "Minor Potion" }, "Descriptions": { "1": "Poção que recupera um pouco de vida.", "2": "Potion that restores a little of health." }, "HealthModifier": 10, "IsUseable": true, "CreatedAt": "2015-05-04T02:07:10.7216263-04:00", "UpdatedAt": "2015-05-04T02:07:10.7216263-04:00" }, "Value": 2 } ] } 

However, you mentioned that your JSON was coming from Postgresql. What does that JSON look like? You may need to adapt your serialization or classes to what you are actually receiving.