net 6.0: dynamically returning child object in response

Question

I have a response class.

public class Response
{
      [JsonPropertyName("number")]
      public int? number { get; set; }
      [JsonIgnore]
      public string WithClientInfo { get; set; }
      [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
      public ClientResponse client
      {
         get { return WithClientInfo == "J" ? client : null; }
         set { }
      }
}

Query:

  var query = from table1 in _unitOfWork.table1.All(_pageParameters)
              from table2 in _unitOfWork.table2.All(null).Where(x => x.Nr_X == table1.Nr_X).DefaultIfEmpty()
              from table3 in _unitOfWork.table3.All(null).Where(x => x.Nr_Y == table1.Nr_Y).DefaultIfEmpty()
              select new Response
              {
                number = table1.Nr_X,
                WithClientInfo = "N",
                Client = new ClientResponse
                {
                    //fields
                }
              }

How can i conditionally fill the response with the Client information. I mean based on a condition i want the Client in the response or not. I'm using System.Text.Json and .net 6. I have tried the [JsonIgnore] attribute but the no results. The app crashes.

This is a MVC app with uses controller.

Answer 1

Is this a WebAPI or a MVC app which uses Controllers?

Here's an example of how I do that in my .NET 6.0 WebAPI using a Controller.

public ActionResult DeleteData(String key){

  // Notice that this method returns an ActionResult type.

  // We do the work to attempt to delete the item.
  // I've removed the code to simplify the example
   // then we return the result
 // deletedCount gets set to a value great than 0 if record(s) were deleted
 // set up a basic nullable JsonResult object (ActionResult) 
 Object? jsonResult = null;
        if (deletedCount > 0){
            jsonResult = new {success=(deletedCount > 0),message="Encrypted data & all associated data has been deleted."};
        }
        else{
            jsonResult = new {success=(deletedCount > 0),message="Data does not exist for associated Cya Secret ID (MainToken). No data deleted."};
        }
        return new JsonResult(jsonResult);

}

The resulting JSON will look something like the following:

{success:true,message:"Encrypted data & all associated data has been deleted."}

or

{success:false,message="Data does not exist for associated Cya Secret ID (MainToken). No data deleted."}

Returning a Model Object As JsonResult

Maybe you're trying to return a Model object as a JsonResult? You can do that by defining your normal class for example:

public class Thing{
    public Int64 Id{get;set;}
    
    // We don't want this value exposed to end user
    [System.Text.Json.Serialization.JsonIgnore]
    public Int64 MainTokenId{get;set;}
    public String Data{get;set;}
    public String AnotherField{get;set;}
    public DateTime? Created {get;set;}
    public DateTime? Updated{get;set;}
    public bool Active{get;set;}

    public Thing(Int64 mainTokenId){
        MainTokenId = mainTokenId;
    }
}

Next, in our Controller we might have an action method that returns this object like the following:

public ActionResult GetThing(Int64 id){
    // do work to load item from DB
    // .
    // .
    // .
    Thing t = LoadThingFromDb();
    // return object as JSON
    return new JsonResult(t);
}

Looks like you just need to do the following:

public class Response
    {
      [JsonPropertyName("number")]
      public int? number { get; set; }
      [JsonIgnore]
      public string WithClientInfo { get; set; }

      // ### Add this attribute #####
      [System.Text.Json.Serialization.JsonIgnore]
      public ClientResponse client
      {
         get { return WithClientInfo == "J" ? client : null; }
         set { }
      }

}

Custom DTO (Data Transfer Object)

If you want to return specific object properties based upon a condition you'll have create a DTO.

Somewhere in your code you have your ClientResponse object.

You can create a anonymous object and return it after wrapping it in a JsonResult

// I guess your main class is named Response so...
    Response r = new Response();

if (conditionYouWantIsTrue){
    return JsonResult(new { prop1 = r.Prop1, prop2 = r.Prop2, prop3 = r.Prop3, prop4 = r.Prop4});
}
else {
     return JsonResult(new { prop3 = r.Prop3, prop4 = r.Prop4});
}

Update

This is because you are using Functional programming paradigm within your algorithmic code.

That means you are making a huge functional call then not knowing where to handle your logic.

You'll have to handle the logic after the query object is filled.

Something like:

var query = from table1 in _unitOfWork.table1.All(_pageParameters)
              from table2 in _unitOfWork.table2.All(null).Where(x => x.Nr_X == table1.Nr_X).DefaultIfEmpty()
              from table3 in _unitOfWork.table3.All(null).Where(x => x.Nr_Y == table1.Nr_Y).DefaultIfEmpty()
              select new Response
              {
                number = table1.Nr_X,
                WithClientInfo = "N",
                Client = new ClientResponse
                {
                    //fields
                }
              }

// this code runs after the query result is filled
    if (conditionYouWant){
        return JsonResult(new {prop1 = query.prop1, prop2 = query.prop2, prop3 = query.prop3});
    }
    else{
            return JsonResult(new {prop1 = query.prop1});
    }