Pulling an Array from a JSON object in C# (New

Question

I'm using Newtonsoft JSON in C#.

I have a log file which I am trying to parse so I can populate a database with the data in the log file.

In the log file, each line is a separate JSON object.

Here is what the log file looks like:

{ "timestamp":"2020-02-02T04:49:53Z", "event":"Friends", "Status":"Online", "Name":"User1" }
{ "timestamp":"2020-02-02T04:48:06Z", "event":"Commander", "FID":"F2", "Name":"User2" }
{ "timestamp":"2020-02-02T04:48:06Z", "event":"Materials", "Raw":[ { "Name":"cadmium", "Count":9},
      { "Name":"zinc", "Count":45 }, { "Name":"iron", "Count":71 }]}

Here's what I'm doing so far:

var fullPath = @"X:\Data\Log Files\test log.log";
string[] lines = File.ReadAllLines(fullPath);

            foreach (var line in lines)
        {
            var json = JObject.Parse(line);
            var eventType = json["event"].Value<string>();

            JArray raw = (JArray)line["Raw"];

            switch (eventType)
               {
                case "Friends":

                    var status = json["Status"].Value<string>();
                    var frName = json["Name"].Value<string>();

                    Console.WriteLine("The friend " + frName + " is currently " + status + ".");

                    Console.WriteLine(json);

                    break;

                case "Commander":

                    var fid = json["FID"].Value<string>();
                    var CMDR = json["Name"].Value<string>();

                    Console.WriteLine("User " + CMDR + " with ID " + ".");

                    Console.WriteLine(json);

                    break;

                case "Materials":


                    //do something here that is magical.

                    break;

                default:
                    Console.WriteLine("N/A");
                    break;
            }

The first two cases work fine. However, I can't figure out how to get the array "Raw" out of the "Materials" event.

FYI - there are two other arrays in that line. So, I need to be able to extract the array for "Raw" as well as the others.

So far, I just can't figure this out.

I'm very much a beginner, so please explain this as if you were talking to a toddler. :)

please help with this?

Thanks so much!

Answer 1

Thank you all for your answers.

I ended up doing something close to what Coffee suggested.

First, I added a class file to my solution. Then, copied the JSON string and did "Edit>Paste Special>Paste JSON as Classes" which created this:

public class Materials
{
public DateTime timestamp { get; set; }
public string _event { get; set; }
public Raw[] Raw { get; set; }
}

public class Raw
{
public string Name { get; set; }
public int Count { get; set; }
}

Then, I deserialized the object into a list:

{
case "Materials":

//do something here that is magical.

Materials m = JsonConvert.DeserializeObject<Materials>(line);
List<Raw> r = m.Raw.ToList();

break;
}

This seemed to do the trick. What do you guys think?

Answer 2

All of the answers above are completely valid for the question you're asking, however, for better code readability and debugging you're better converting those json strings to actual c# objects. For example you'd set up some models like this:

public class Friends
{
    public string Timestamp { get; set; }
    public string Event { get; set; }
    public string Status { get; set; }
    public string Name { get; set; }
}

public class Commander
{
    public string Timestamp { get; set; }
    public string Event { get; set; }
    public string FID { get; set; }
    public string Name { get; set; }
}

public class Materials
{
    public string Timestamp { get; set; }
    public string Event { get; set; }
    public List<Material> Raw { get; set; }
}

public class Material
{
    public string Name { get; set; }
    public string Count { get; set; }
}

You'd have 1 model for each of your different log types. Now in your logic what you want to do is read the event type from the JSON and then turn that into a valid c# type (in my code below I use a dictionary) and then use that type to tell the JsonConvert.DeserializeObject method what to convert your json string into, this is how I implemented it:

//Same as your code
        var fullPath = @"C:\testLog.log";
        string[] lines = File.ReadAllLines(fullPath);

        //This dictionary stores each of your different log types in a way where you can use the "event" string in each json to get the c# object type
        Dictionary<string, Type> types = new Dictionary<string, Type>()
        {
            { "Friends", typeof(Friends)},
            {"Commander", typeof(Commander) },
            {"Materials", typeof(Materials) }
        };

        foreach (var line in lines)
        {
            //Same as your code
            var json = JObject.Parse(line);
            Type eventType = types[json["event"].Value<string>()];

            //This line will use the event type provided by the json to deserialise your object
            var x = JsonConvert.DeserializeObject(line, eventType);

            switch (x)
            {
                case Friends friendObject:
                    //Do stuff with the friend object here
                    Console.WriteLine("Friend log found");
                    Console.WriteLine(friendObject.Timestamp);
                    Console.WriteLine(friendObject.Name);
                    Console.WriteLine(friendObject.Status);
                    Console.WriteLine();
                    break;
                case Commander commanderObject:
                    //Do stuff with the commander object here
                    Console.WriteLine("Commander log found");
                    Console.WriteLine(commanderObject.Timestamp);
                    Console.WriteLine(commanderObject.FID);
                    Console.WriteLine(commanderObject.Name);
                    Console.WriteLine();
                    break;
                case Materials materialsObject:
                    //do stuff with the material object here
                    Console.WriteLine("Materials log found");
                    Console.WriteLine(materialsObject.Timestamp);
                    materialsObject.Raw.ForEach(material=>Console.WriteLine(material.Name + ". Count: " + material.Count));
                    break;
            }
        }

Answer 3

Instead of going line by line, I suggest to ReadAllText and loop the JsonArray

var json = JArray.Parse(File.ReadAllText(fullPath));
foreach (var jsonItem in json)
{
    var eventType = jsonItem["event"].ToString();
    switch (eventType)
    {
        case "Friends":
            var status = jsonItem["Status"].Value<string>();
            var frName = jsonItem["Name"].Value<string>();
            Console.WriteLine("The friend " + frName + " is currently " + status + ".");
            break;
        case "Commander":
            var fid = jsonItem["FID"].Value<string>();
            var CMDR = jsonItem["Name"].Value<string>();
            Console.WriteLine("User " + CMDR + " with ID " + ".");
            break;
        case "Materials":
            //Your magic code here
            var raw = JArray.Parse(jsonItem["Raw"].ToString());
            foreach (var rawItem in raw)
            {
                Console.WriteLine("Name " + rawItem["Name"] + " with Count " + rawItem["Count"] + ".");
            }
            break;
        default:
            Console.WriteLine("N/A");
            break;
    }
}

Answer 4

You need to parse an array of JToken. Please try this :

foreach (var line in lines)
        {
            var json = JObject.Parse(line);
            var eventType = json["event"].Value<string>();


            switch (eventType)
            {
                case "Friends":

                    var status = json["Status"].Value<string>();
                    var frName = json["Name"].Value<string>();

                    Console.WriteLine("The friend " + frName + " is currently " + status + ".");

                    Console.WriteLine(json);

                    break;

                case "Commander":

                    var fid = json["FID"].Value<string>();
                    var CMDR = json["Name"].Value<string>();

                    Console.WriteLine("User " + CMDR + " with ID " + ".");

                    Console.WriteLine(json);

                    break;

                case "Materials":
                    var raw = JArray.Parse(json["Raw"].ToString());

                    foreach(JToken token in raw)
                    {
                        Console.WriteLine("Name " + token["Name"] + " Counter " + token["Count"]);
                    }


                    break;

                default:
                    Console.WriteLine("N/A");
                    break;
            }
        }

Hope it will help you.

Answer 5

You could do the following.

  var eventType = json["event"].Value<string>();
  Console.WriteLine($"Event Type {eventType}");
  foreach(var obj in json["Raw"])
  {
    Console.WriteLine($"Name={obj["Name"]},Count = {obj["Count"]}");
  }

You are in this case, parsing the "Raw" array from the Json Object and iterating over the JObjects to fetch each element in the array