Passing Json information to object constructor when deserializing

Question

I have a Json file that is composed of nested serialized objects.
When deserializing this file I get my nested object reconstructed as needed, doing the following:

var SomeNestedObjects= JsonConvert.DeserializeObject<SomeNestedObjectsFormat>(File.ReadAllText(@"e:\file.json"));

Now, everything works great because my system has a definition of all these nested object and the JsonConverter is therefore able to create and initialise the lot out of whatever is in that Json file.

What I would like to do though is to have a dummy module that is empty and gets constructed/built/populated at runtime based on what is found in the Json file. Let's take the following Json file as an example, containing 1 module composed of 2 parameters:

{
  "Name": "DummyModule",
  "param1": {
    "Value": 456,
    "Name": "Param1",
    "MinValue": 0,
    "MaxValue": 500
  },
  "param2": {
    "Value": false,
    "Name": "Param2",
    "MinValue": false,
    "MaxValue": true
  }
}

Now, my system has a class Parameter, but my DummyModule class does not know anything about Param1 and Param2. The reason is that this DummyModule can be composed of anything and can change at runtime.

So what I would like to do is to be able to add properties to my DummyModule at runtime when I read my Json. In order to do so, I would need to do some magic within my DummyModule constructor based on that is read out of the Json.
Problem is that I don't know how my constructor can access or be passed information about the Json file. Here is my DummyModule() class:

public class DummyModule
{
    public string Name { get; set; }

    [JsonConstructor]
    public DummyModule()
    {
        // Use Json Object here to create/add my "Param1" and "Param2" properties on the fly
        // ...

        // Something of the sort:       
        foreach (var param in jsonObject)
            CreateProperty(tb, param.FieldName, param.FieldType);
    }
}

Maybe you could find the best answer to this question useful: stackoverflow.com/questions/23017716/… — claudiom248
– claudiom248, Commented Mar 5, 2020 at 14:14
Thanks, I have done something of the sort before, but I was hopping not to require all that extra logic. If only I could get the loaded Json data passed to my DummyModule() constructor without all that. — stackMeUp
– stackMeUp, Commented Mar 5, 2020 at 14:23

tzrm · Accepted Answer · 2020-03-05 15:38:21Z

1

If your object doesn't have to be DummyModule type, you can use ExpandoObject as your destination type to deserialize the JSON:

The ExpandoObject class enables you to add and delete members of its instances at run time and also to set and get values of these members.

dynamic myObject = JsonConvert.DeserializeObject<ExpandoObject>(File.ReadAllText(@"e:\file.json"));

Console.WriteLine(myObject.Name);
Console.WriteLine(myObject.Name.GetType());

Console.WriteLine(myObject.param1.Value);
Console.WriteLine(myObject.param1.Value.GetType());

And this would be the output:

answered Mar 5, 2020 at 15:38

tzrm

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1 Comment

stackMeUp Over a year ago

Thanks, yes you need the module base as it will contain methods (that cannot be in the Json). Also, there will be a mix of well defined objects and DummyModules. So the deserialization will break that way.

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