SSIS C# Script task source deserializing JSon one entry per row

This block of code throws an exception

String json = DownloadJson("http://someapi.com");
Output0Buffer.AddRow();
Output0Buffer.gameid = json;

It's likely overflowing whatever length you have defined for the string column. But, I had a lunch hour so you have a solution, of sorts ;)

What I did different

I defined a member variable myArray which is an old-school array of type MyArray. When we turn the json into objects, this will be the list that will be at the per item level (game1, game2, etc).

In my PreExecute method, I will download the json and convert it into an in instance of our class typed as an array.

I struck the Root, MyArrayList definitions as I was getting ambiguous definition errors trying to unpack the json.

I removed the enumerator and the lowercased gameid from your MyArray class as the json indicates it should be the first definition of gameId

In my CreateNewOutputRows, I am going to enumerate through the member array and for each item I find, I am going add a new row to the output buffer and then populate it with data.

using System;
using System.Data;
using Microsoft.SqlServer.Dts.Pipeline.Wrapper;
using Microsoft.SqlServer.Dts.Runtime.Wrapper;
using System.Collections.Generic;
using System.Net;
// Add reference to System.Web.Extensions
using System.Web.Script.Serialization;
using System.Collections;

// Root myDeserializedClass = JsonConvert.DeserializeObject<Root>(myJsonResponse); 
public class MyArray
{
    public string gameId { get; set; }
    public string name { get; set; }
    public int width { get; set; }
    public int height { get; set; }
    public string description { get; set; }
    public string themeUrl { get; set; }
    public string thumbnailUrl { get; set; }
    public string verticalThumbnailUrl { get; set; }
    public string helpUrl { get; set; }
    public List<string> trivia { get; set; }
    public List<object> traits { get; set; }
    public string seoName { get; set; }
    public string friendlyName { get; set; }


}

/// <summary>
/// This is the class to which to add your code.  Do not change the name, attributes, or parent
/// of this class.
/// </summary>
[Microsoft.SqlServer.Dts.Pipeline.SSISScriptComponentEntryPointAttribute]
public class ScriptMain : UserComponent
{
    //Root rootDocument;
    MyArray[] myArray;

    public string DownloadJson(string downloadURL)
    {
        return @"[
{
            'gameId': 'a_string_id',
    'name': 'A string with the name',
    'width': 1280,
    'height': 720,
    'description': 'A lot of mumble jumble A lot of mumble jumble A lot of mumble jumble A lot of mumble jumble A lot of mumble jumble A lot of mumble jumble A lot of mumble jumble A lot of mumble jumble A lot of mumble jumble A lot of mumble jumble',
    'themeUrl': '/address1/address2/address3/filename.jpg',
    'thumbnailUrl': '/address1/address2/address3/filename.jpg',
    'verticalThumbnailUrl': '',
    'helpUrl': '',
    'trivia': [],
    'traits': [
      'aString'
    ],
    'seoName': 'a-long-name',
    'friendlyName': 'a-friendly-name'
  },
  {
    'gameId': 'a_string_id',
    'name': 'A string with the name',
    'width': 1600,
    'height': 878,
    'description': '',
    'themeUrl': '/address1/address2/address3/filename.jpg',
    'thumbnailUrl': '/address1/address2/address3/filename.jpg',
    'verticalThumbnailUrl': '',
    'helpUrl': '',
    'trivia': [],
    'traits': [],
    'seoName': 'a-long-name',
    'friendlyName': 'a-friendly-name'
  }
]";
        //using (WebClient client = new WebClient())
        //{
        //    return client.DownloadString(downloadURL);
        //}
    }

    public override void PreExecute()
    {
        base.PreExecute();
        // You likely want to have this as a Variable and passed in to the method
        string json = DownloadJson("http://someapi.com");

        JavaScriptSerializer serialize = new JavaScriptSerializer();
    myArray = serialize.Deserialize<MyArray[]>(json);

}

    /// <summary>
    /// This method is called after all the rows have passed through this component.
    ///
    /// You can delete this method if you don't need to do anything here.
    /// </summary>
    public override void PostExecute()
    {
        base.PostExecute();
    }

    public override void CreateNewOutputRows()
    {
        foreach (var item in this.myArray)
        {
            Output0Buffer.AddRow();
            Output0Buffer.gameid = item.gameId;
            Output0Buffer.height = item.height;
            Output0Buffer.width = item.width;
            Output0Buffer.name = item.name;
        }
    }

}

In the Inputs and Outputs tab, I have defined 4 of the N columns you have in the MyArray class. Be sure to adjust the DataType and the Length of these to match the maximum expected length. If you need to deal with unicode data, you might need to switch that to Unicode string/DT_WSTR data type.

You can see here I have the two rows flowing through and I have data.

Not addressed in this solution

MyArray has two lists within it: trivia and traits. You won't be able to add them as-is to the buffer because that's not a thing. Pedantic answer is yes you can but realistic answer is don't from the guy with 15 years of doing SSIS.

For these two columns, the answer is driven by how are you going to store this data? Maybe it's going to a table with a poor design decision like storing a delimited list. That's the "easiest" to deal with as you could just zip the data together like

Output0Buffer.trivia = string.Join(";", item.trivia);

That code is approximately correct but it doesn't check for those collections being null or whether the delimiter already exists in it. At any rate, that is for you the data knowledge worker to decide.

A different approach might be that you create an OutputTrivaBuffer and send gameId and a single trivia value down a separate path.

There's no error handling at all so you'll want to fortify this code.

You'll likely want to add a Variable to the SSIS package with the API's url in it and then pass that as a ReadOnly parameter to the Script Component so you can point at different end points (dev/prod) without editing the package.