NHinernate - Serializing Criteria to json and back. for a web interface usage - nhibernate

Question

I have a web interface with a lot of data grids that allow the user passing a search criteria to the server.
I don't want to actually build an explicit method that will handle each grid individually, so I thought to allow passing JSON criteria from the client to the server.
This code
string res = JsonConvert.SerializeObject(Restrictions.Eq("id", "1"));
will return will return {"PropertyName":"id","Value":"1"} which is exactly what I wanted to pass from the client - perfect.
but this code with or statement:
string res = JsonConvert.SerializeObject(Restrictions.Or(Restrictions.Eq("id", "1"),Restrictions.Eq("id", "2")))
will return {}
What is the way to convert JSON into a Criteria and back in nHibernate.
To be more accurate, I have something like this in the client, and I want my server to support it. I can serialize the client ui to json.
Thanks

Answer 1

The empty json serialization happens because newtonsoft can only serialize public fields.
The code below will serialize all fields of a class regardless of its visibility.
public class MyContractResolver : DefaultContractResolver
{
protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
{
var props = type.GetProperties(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
.Select(p => base.CreateProperty(p, memberSerialization))
.Union(type.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
.Select(f => base.CreateProperty(f, memberSerialization)))
.ToList();
props.ForEach(p => { p.Writable = true; p.Readable = true; });
return props;
}
}
...
var myOrs = Restrictions.Or(Restrictions.Eq("id", "1"), Restrictions.Eq("id", "2"));
var settings = new JsonSerializerSettings()
{
ContractResolver = new MyContractResolver()
};
string json = JsonConvert.SerializeObject(myOrs, settings);
Now to deserialize this json we have a problem, the NHibernate classes are either abstract or don't have a public empty constructor.
You will need to create a custom class to deserialize.
public class MyConverter : JsonConverter
{
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException("Not implemented yet");
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
JObject obj = JObject.Load(reader);
if (obj.Value<string>("Op") == "or")
{
var leftJObject = obj["LeftHandSide"];
var rightJObject = obj["RightHandSide"];
var left = new SimpleExpression(leftJObject.Value<string>("PropertyName"), GetJTokenValue(leftJObject["Value"]), leftJObject.Value<string>("Op"));
var right = new SimpleExpression(rightJObject.Value<string>("PropertyName"), GetJTokenValue(rightJObject["Value"]), rightJObject.Value<string>("Op"));
return Restrictions.Or(left, right);
}
//TODO: The rest of the restrictions
return null;
}
public override bool CanWrite
{
get { return false; }
}
public override bool CanConvert(Type objectType)
{
return true;
}
private object GetJTokenValue(JToken token)
{
if (token.Type == JTokenType.String)
{
return token.Value<string>();
}
else if (token.Type == JTokenType.Integer)
{
return token.Value<Int32>();
}
//TODO: The rest of the types
return null;
}
}
...
var result = JsonConvert.DeserializeObject<AbstractCriterion>(json, new MyConverter());