question

@leatherboundgames@gmail.com - I'm moving to a new Answer, so that I have sufficient room to cover everything

There are a mix of issues with the snippet in question:

1. How are you calling ExecuteCloudScript, and how are you passing in the Key/Value pair you've created? Bear in mind that FunctionParameter is itself a JSON object, so you may need to pass them in as something like "keyName": string and "valueString": string, so that you can then parse them as individual elements from args.

2. SimpleJson isn't part of JavaScript - it's in our Unity SDK. In JavaScript, you can parse a string into a JSON object with JSON.parse(string), and you can turn an object into a string with JSON.stringify(object).

3. I'd recommend being very careful with how you form JavaScript calls, as the language tries to "help" a lot, which can result in it doing something utterly unlike what you intended. In this case, using a ...Request object (the way we do in the SDK) to create your call to the Server API is likely tripping you up.

For your call, I would actually do with something like the code from the post linked above (https://community.playfab.com/questions/3859/way-to-use-variables-to-set-kvp-data-in-cloud-scri.html). But here's the same code, modified to fit your specific use case. For this call, you need to pass in the Key and Value as described above.

handlers.UpdateUserData = function (args) {

    var dataPayload = {};

    dataPayload[args.keyName] = args.valueString;

    var result = server.UpdateUserReadOnlyData({
        PlayFabId: currentPlayerId,
        Data: dataPayload
    });
}

I'm creating a new answer for anyone else to see summarizing what is going on.

To send a KeyValuePair to a CloudScript Function through the FunctionParameter of ExecuteCloudScriptRequest it has to be a Json object.

(Link to Json structure examples)

Sending a Json object to CloudScript however needs to have "keyName" and "valueString" there to define the object as a KeyValuePair with the strings for your key and value set to them respectively otherwise sending just your key and value in a Json object your Data in your CloudScript UpdateUserData function won't be able to be read.

Your Client-Side ExecuteCloudScript function can be set up like this to receive two variables. (C#)

public void updateUserData(string keyname, string value)

{
   ExecuteCloudScriptRequest request = new ExecuteCloudScriptRequest;
   {
       FunctionName = "UpdateUserData",
       GeneratePlayStreamEvent = true,
       FunctionParameter = new Dictionary<string,object> { {"keyName", keyname }, { "valueString", value } }
};

   PlayFabClientAPI.ExecuteCloudScript(request, yourCallBackFunction, null);
}

//Note: To access Dictionary you need to add using system.collections.generic; to the top of your script.

This should then call the following CloudScript function called "UpdateUserData":

handlers.UpdateUserData = function(args)

{

   var dataPayload = {};

   dataPayLoad[args.keyName] = args.valueString;

   var result = server.UpdateUserReadOnlyData({

   PlayFabId: currentPlayerId,

   Data: dataPayLoad

   });

Now if you go to your gameManager>Players>PlayerYouUpdatedDataFor you will see the keyname and value strings you sent from the client in the Key,Value pair boxes ready to be used in GetUserData().