Deserialize Json to Generic Type

One of the recent question in stackoverflow found interesting was about a Json, which needs to be deserialized to a Generic Class. What makes the question interesting was the Generic Property would have a different Json Property name depending on the type T. Consider the following Json

{
status: false,
employee:
{
firstName: "Test",
lastName: "Test_Last"
}
}

This needs to be Deseriliazed to the following class structures

public class Response<T>
{

[JsonProperty(PropertyName = "status")]
public bool Status {get;set;}

public T Item {get;set;}

}

[JsonObject(Title = "employee")]
public class Employee
{

[JsonProperty(PropertyName = "firstName")]
public string FirstName {get; set;}

[JsonProperty(PropertyName = "lastName")]
public string LastName {get; set;}

}

 

However, Response<T> being a generic class, would need to support additional Types as well. For example, the Json could also look like the following

{
status: false,
company:
{
companyname: "company name",
headquaters: "location"
}
}

Where the company needs to be deserialized to

[JsonObject(Title = "company")]
public class Employee {

[JsonProperty(PropertyName = "companyname")]
public string CompanyName {get; set;}

[JsonProperty(PropertyName = "headquaters")]
public string HeadQuaters {get; set;}

}

The solution lies in writing a Custom Contract Resolver, which does the magic. Let’s go ahead and write the ContractResolver.

public class GenericContractResolver<T> : DefaultContractResolver
{

protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
var property = base.CreateProperty(member, memberSerialization);
if (property.UnderlyingName == nameof(Response<T>.Item))
{
foreach( var attribute in System.Attribute.GetCustomAttributes(typeof(T)))
{
if(attribute is JsonObjectAttribute jobject)
{
property.PropertyName = jobject.Title;
}
}
}
return property;
}
}

The role of the ContractResolver is pretty simple. As soon as it recognizes the Generic Type passed, it would replace the property name with the name described in JsonObjectAttribute.

Now you can use the ContractResolver to deserialize the Json. For example

var result = JsonConvert.DeserializeObject<Response<Employee>>(json,
new JsonSerializerSettings
{
ContractResolver = new GenericContractResolver<Employee>()
});

Demo Samples could be found here in my C# Fiddles