What I want

I want to send a limited/reduced class/object to frontend (as JSON). I use .NET Core 5.

What I have

I have a model class like this:

namespace Tasks.Models
{
    public class Resources
    {
        public Guid Id { get; set; }
        public string Type { get; set; }
        public string Url { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
        public DateTime? Createdon { get; set; }
        public Guid Userid { get; set; }
        public Guid Taskid { get; set; }
        public int Clicked { get; set; }
        public byte Active { get; set; }
            many more properties
    }
}

Now depending on the which controller that calls this model I want to have different "kind" of models. So if the resource is file I maybe want the properties Id,Type,Name. But if the resource is URL I want Id, Url, Name.

I tried setting up a method that "initialized the fields I wanted, but that also returned all properties

public static Responses FileResponse()
{
    var response = new Responses()
    {
        Id = new Guid(),
        Name = "",
        Type = "File",
    };

    return response;
}

Now, when I call the Resources class or this method I get all properties, and returning it to the view presents all properties, but mostly as null, because I only set the three fields in the method.

What is the recommended way of solving this?

CodePudding user response：

If you want to remove the field if it's null instead of showing in json with null value.

    public class Resources
    {
        public Guid Id { get; set; }
        public string Type { get; set; }
        // if null, dont show it in JSON output
        [JsonIgnoreAttribute(Condition = JsonIgnoreCondition.WhenWritingNull)]
        public string Url { get; set; }
        // if null, dont show it in JSON output
        [JsonIgnoreAttribute(Condition = JsonIgnoreCondition.WhenWritingNull)]
        public string Name { get; set; }
        public string Description { get; set; }
        public DateTime? Createdon { get; set; }
        public Guid Userid { get; set; }
        public Guid Taskid { get; set; }
        public int Clicked { get; set; }
        public byte Active { get; set; }
    }

PS: Fiddle https://dotnetfiddle.net/hiMAci

CodePudding user response：

It is just limiting the Resource class I am not able to do

Yep, side effect of C# being strongly typed, with object X definitely having properties Y and Z. You need differently shaped objects - either full on classes or records - that name the reduced set of properties because the serializer is going to look a tthe object and ser every property it can find.

You could make a new class for every variation - quick and easy with records, and easy to pass around inside your C#:

public record FileThing(string Id, string Type, string Name);

//make a new one and return it
new FileThing(someResources.Id, someResources.Type, someResources.Name);

Or can consider using an anonymous type if you're literally looking to put a few properties into some json, down a socket to a consuming front end (I can't quite decide what you mean by "view" - it doesn't seem to be an MVC View) that only cares about a few props out of many

So if the resource is file I maybe want the properties Id,Type,Name. But if the resource is URL I want Id, Url, Name.

public ActionResult SomeControllerMethod(){

  if(isFile)
    return Ok(new { someResources.Id, someResources.Type, someResources.Name });
  else if(isUrl)
    return Ok(new { someResources.Id, someResources.Url, someResources.Name });

}

Anonymous types are a bit harder to work with because the compiler writes the class for you, so it's tricky to do things like declare return types from methods if the method is returning an AT.. But if you're using it as some fill-in all within one method, such as a "make this and serialize it", they work well..