Api Calls

Now that we've successfully crafted the different queries, mutations and subscriptions needed for our matchmaking, we need to write some code to actually implement the logic.

First off, we head into GameData.cs script which is contains some code that determines gameplay and whatnot.

GameData.cs can be found in Assets/_Game/Scripts/Data/GameData.cs

First off, ensure that we include the necessary namespaces we'd be utilizing.

using System;
using System.Collections.Generic;
using System.Net.WebSockets;
using System.Threading.Tasks;
using Game.Manager;
using GraphQlClient.Core;
using GraphQlClient.EventCallbacks;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.SceneManagement;
using Random = UnityEngine.Random;

Next, we create a Battles class which would have fields matching that of our battles table in Hasura.

This is useful in Deserializing the JSON data gotten from Hasura.

public class Battles {
public List<Battles> returning;
public int id;
public int shooter_id;
public int defender_id;
public Game.Data.User.Users shooter;
public Game.Data.User.Users defender;
public bool shooterReady;
public bool defenderReady;

Note, the Battles class is created within the GameData class.

As you can see, the Battles class mimics the type of object that can be returned from our Hasura backend.

Next, we have to define some variables that would be used in our game logic.

Add the code below beneath the other variables that have been declared in GameData.cs.

public GraphApi shooterApi;
public Battles battle;
public float waitingTime;
public ClientWebSocket battleCws;

Let's understand the use of these variables.

  • GraphApi shooterApi: This is a variable to house our Api Reference. We need this reference to be able to use the queries, mutations and subscriptions we created.
  • Battles battle: This is a variable to house battle data gotten from our Hasura backend. Data gotten from the backend will be deserialized into this variable.
  • float waitingTime: This is the amount of time we intend to wait for an opponent to join our open games. If no one joins before the waiting time runs out, we delete the open battle.
  • ClientWebSocket battleCws: This is a ClientWebSocket reference we shall use for subscribing to our battles table from our Hasura backend.

After adding these variables, your Variable Declaration region should look like

#region Variable Declaration
public Sounds sounds;
public User user;
public ColorScheme colorScheme;
public GraphApi shooterApi;
public GameManager gameManager;
public MenuManager menuManager;
public AudioSource sfxPlayer;
public int bullets;
public List<int> hitTargets;
public List<int> defendedTargets;
public bool shouldCount;
public float time;
public bool inBattle;
public GameObject bulletPrefab;
private Vector3 opponentPosition;
private int misses;
private bool attackComplete;
private bool gameComplete;
public Battles battle;
public float waitingTime;
public ClientWebSocket battleCws;

Since GameData.cs is a ScriptableObject, it retains data.

Therefore we need a function that resets it to default values. This is the Reset() function that is called when GameData is enabled.

We'd add the default values for the new variables we just created by adding the code below into Reset()

battle = null;
battleCws = null;
waitingTime = 20;

Your entire Reset() function should look like this.

public void Reset(){
bullets = user.role == User.Role.SHOOTER ? 7 : 10;
hitTargets = new List<int>();
defendedTargets = new List<int>();
shouldCount = false;
time = 0;
gameComplete = false;
attackComplete = false;
misses = 0;
opponentPosition = new Vector3(0, 1, 75);
battle = null;
battleCws = null;
waitingTime = 20;

Api Calls

We've created variables but now we must write the functions that will get information from our backend.

Copy and paste the code below into GameData.cs and function shall be explained.

#region Api Calls
public async Task<List<Battles>> GetOnlineBattles(){
GraphApi.Query onlineBattle = shooterApi.GetQueryByName("GetOnlineBattles", GraphApi.Query.Type.Query);
UnityWebRequest request = await shooterApi.Post(onlineBattle);
string result = request.downloadHandler.text;
return JsonConvert.DeserializeObject<List<Battles>>(RemoveData(result,
public async Task<Battles> CreateBattle(){
GraphApi.Query createBattle = shooterApi.GetQueryByName("CreateBattle", GraphApi.Query.Type.Mutation);
createBattle.SetArgs(new{objects = new{shooter_id = 1}});
UnityWebRequest request = await shooterApi.Post(createBattle);
string result = request.downloadHandler.text;
return JsonConvert.DeserializeObject<Battles>(RemoveData(result,
private async void UpdateShooterReady(){
GraphApi.Query updateBattle = shooterApi.GetQueryByName("UpdateOnlineBattle", GraphApi.Query.Type.Mutation);
updateBattle.SetArgs(new{where = new{id = new{_eq = battle.id}}, _set = new{shooterReady = true}});
await shooterApi.Post(updateBattle);
public async Task<Battles> UpdateBattle(int id){
GraphApi.Query updateBattle = shooterApi.GetQueryByName("UpdateOnlineBattle", GraphApi.Query.Type.Mutation);
{where = new{id = new{_eq = id}}, _set = new{defender_id = 2, defenderReady = true}});
UnityWebRequest request = await shooterApi.Post(updateBattle);
string result = request.downloadHandler.text;
return JsonConvert.DeserializeObject<Battles>(RemoveData(result,
private async Task DeleteBattles(){
GraphApi.Query deleteBattle = shooterApi.GetQueryByName("DeleteBattle", GraphApi.Query.Type.Mutation);
deleteBattle.SetArgs(new{where = new{id = new{_eq = battle?.id}}});
await shooterApi.Post(deleteBattle);
public async Task DeleteOldBattles(){
GraphApi.Query deleteBattle = shooterApi.GetQueryByName("DeleteOldBattles", GraphApi.Query.Type.Mutation);
deleteBattle.SetArgs(new{where = new{}});
await shooterApi.Post(deleteBattle);
public async void BattleSubscribe(int battleId){
GraphApi.Query battleSubscribe =
shooterApi.GetQueryByName("SubscribeToBattle", GraphApi.Query.Type.Subscription);
battleSubscribe.SetArgs(new{id = battleId});
battleCws = await shooterApi.Subscribe(battleSubscribe, "battle");
private void ReceiveBattleData(OnSubscriptionDataReceived subscriptionDataReceived){
battle = JsonConvert.DeserializeObject<Battles>(RemoveSubscriptionData(subscriptionDataReceived.data,
shooterApi.GetQueryByName("SubscribeToBattle", GraphApi.Query.Type.Subscription).queryString));
if (battle == null){
shooterApi.CancelSubscription(battleCws, "battle");
if (!battle.shooterReady && battle.defenderReady){
string opponentName =
user.role == User.Role.SHOOTER ? battle.defender.username : battle.shooter.username;
menuManager.SetWaitingText($"Found an opponent. {opponentName}");
waitingTime = 10;
if (user.role == User.Role.SHOOTER)
if (battle.shooterReady && battle.defenderReady && SceneManager.GetActiveScene().buildIndex == 0){
string opponentName =
user.role == User.Role.SHOOTER ? battle.defender.username : battle.shooter.username;
menuManager.SetWaitingText($"Entering battle against. {opponentName}");
if (!inBattle){
inBattle = true;
public async void StartWaiting(){
while (waitingTime >= 0){
await new WaitForSecondsRealtime(1);
if (battle != null){
if (battle.shooterReady && battle.defenderReady)
inBattle = false;
menuManager.SetWaitingText("No opponent found");
shooterApi.CancelSubscription(battleCws, "battle");
await new WaitForSecondsRealtime(1);
await DeleteBattles();

Wow, that's a lot of code! Let's go into breaking it down one function at a time. Don't worry, they're pretty straightforward.

Note: Don't forget to read the documentation for the graphql-client-unity as it'll help understand most of what is going on.


This function calls our GetOnlineBattles query, waits for data to be returned from our backend and deserializes that data.

It returns the deserialized data as List<Battles> which is a list of Battles.


This functions calls our CreateBattle mutation.

The player that creates the battle is the Shooter and the player that joins is the Defender

Within the function, createBattle.SetArgs(new{objects = new{shooter_id = 1}}); sets the shooter_id of the battle to be 1.

Later on, when we've implemented authentication, we would be setting the shooter_id to be the id of the user but for now we use the id of one of the mock users we created.

void UpdateShooterReady

This function calls our UpdateOnlineBattle mutation. It is used to set the shooterReady flag of the battle to true.

This can be seen in this line of code

updateBattle.SetArgs(new{where = new{id = new{_eq = battle.id}}, _set = new{shooterReady = true}}); where the shooterReady flag of battle row of id = battle.id is set to true

At the point we'd use this function, our Battles battle would already have been set.

We would use this function to confirm the availability of the player that creates the battle after a player has joined.


This also calls our UpdateOnlineBattle mutation. But this function is used to join a battle. This can be seen by the arguments in

updateBattle.SetArgs(new {where = new{id = new{_eq = id}}, _set = new{defender_id = 2, defenderReady = true}});

Which sets the defender_id of a battle to 2.

Later on, when we've implemented authentication, we would be setting the defender_id to be the id of the user but for now we use the id of one of the mock users we created.

DeleteBattles and DeleteOldBattles

These are used to delete individual battles and all old battles from our database.

void BattleSubscribe

This calls our SubscribeToBattle subscription. We'd use this to watch out for changes to a created battle.

If the player is the creator of the battle, data is returned when another player joins because the defender_id changes from null to that players id.

If the player is the joiner of the battle, data is returned when the creator confirms availability because the shooterReady flag changes from false to true.

void ReceiveBattleData

This functions is called every time our subscription returns data from the backend. That is, it is called every time a change is made to the battle row we subscribed to.

The function also has the data received within subscriptionDataReceived and this is deserialized into our battle variable so that our battle variable always reflects the current state of the battles row in our database.

The contents of this function performs the flow chart in our Matchmaking

void StartWaiting()

This is used to wait for a particular time. If a battle isn't confirmed by then, it closes the subscription and resets the menu.

Event Listening

For our function void ReceiveBattleData(OnSubscriptionDataReceived subscriptionDataReceived) to be called every time we receive new subscription data, we have to listen to the right event.

This is done by adding this lines of code

private void OnEnable(){
private void OnDisable(){


Go to GameData at Assets/_Game/ScriptableObjects/GameData and drag your Api Reference in the slot for shooterApi

Shooter Api Reference


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